BlueScope Steel Limited v Dongkuk Steel Mill Co., Ltd

Date of last submissions: 24 December 2018

Registry: Victoria

Division: General Division

National Practice Area: Intellectual Property

Sub-area: Patents and Associated Statutes

Category: Catchwords

Number of paragraphs: 1517

Counsel for the Applicant and Cross-Respondent: Mr BN Caine QC and Ms C Cunliffe

Solicitor for the Applicant and Cross-Respondent: King & Wood Mallesons

Counsel for the Respondent and Cross-Claimant: Mr A Ryan SC and Mr JS Cooke

Solicitor for the Respondent and Cross-Claimant: Bird & Bird

BETWEEN: BLUESCOPE STEEL LIMITED (ACN 000 011 058) Applicant

AND: DONGKUK STEEL MILL CO., LTD Respondent

AND BETWEEN: DONGKUK STEEL MILL CO., LTD Cross-Claimant

AND: BLUESCOPE STEEL LIMITED (ACN 000 011 058) Cross-Respondent

JUDGE: BEACH J DATE OF ORDER: 17 December 2019

1. Each of the parties file and serve by 3 February 2020 minutes of orders and short submissions (limited to 3 pages) to give effect to these reasons.
2. Costs reserved.
3. Liberty to apply. Note: Entry of orders is dealt with in Rule 39.32 of the Federal Court Rules 2011.

BEACH J: 1 BlueScope Steel Limited (BlueScope) contends that Dongkuk Steel Mill Co Ltd (Dongkuk) has infringed various claims of Australian Patent No. 2009225257 (the 257 Patent) and Australian Patent No. 2009225258 (the 258 Patent). BlueScope is the registered proprietor of both Patents, the applications for which were filed on 13 March 2009. 2 BlueScope carries on business, inter-alia, as a manufacturer and supplier of alloy-coated steel strip products which are sold in Australia and elsewhere. Dongkuk carries on business outside Australia, inter-alia, as a manufacturer and supplier of alloy-coated steel strip products which are sold by third parties in Australia and elsewhere. 3 The invention the subject of the 257 Patent relates to a hot dip coating method for coating steel strips with an alloy coating of aluminium, zinc, silicon and magnesium (Al-Zn-Si-Mg) where variations in the thickness of the coating are controlled such that there is only a small proportion of Mg2Si particles or substantially no Mg2Si particles in the surface of the coating. The invention also relates to a coated steel strip formed by that method. 4 The invention the subject of the 258 Patent relates to an Al-Zn-Si-Mg alloy-coated steel strip where the distribution of Mg2Si particles is such that there is no more than 10% by weight of Mg2Si particles in a surface region of the coating. The invention also relates to a hot dip coating method for forming such a coated steel strip. 5 BlueScope says that Dongkuk without the licence or authority of BlueScope has imported and authorised other persons to offer for sale, sell and supply in Australia an Al-Zn-Si-Mg alloy-coated steel strip product (the GLX product) that infringes both Patents because it is a product which: (a) results from the use of the method claimed in claims 1, 3, 4, 5, 6, 8, 9, 11, 12 and 13 of the 257 Patent; (b) falls within the scope of claims 14 and 15 of the 257 Patent; and (c) falls within the scope of claims 2, 5, 6, 11 and 12 of the 258 Patent. 6 Now although BlueScope originally pleaded infringement of claim 7 of the 257 Patent, it does not now press that claim. Further, although it originally pleaded infringement of claims 1 and 17 to 25 of the 258 Patent, it no longer presses those claims. 7 Dongkuk has denied infringement and has alleged that BlueScope has made unjustified threats in respect of the alleged infringing conduct asserted by BlueScope. Dongkuk has also cross-claimed seeking orders revoking both the 257 Patent and the 258 Patent in so far as they relate to various claims. 8 Dongkuk has alleged that claims 1, 3 to 6, 8, 9 and 11 to 15 of the 257 Patent are invalid upon the grounds that: (a) the invention is not novel; (b) the invention does not involve an inventive step; (c) the specification does not disclose the best method of performing the invention; (d) the specification does not describe the invention fully; (e) the claims do not define the invention or are not clear; (f) the claims are not fairly based; and (g) the Patent was obtained by false suggestion or misrepresentation. 9 Further, Dongkuk has alleged that claims 1, 2, 5, 6, 11, 12, 17, 18 and 20 to 25 of the 258 Patent are invalid upon similar grounds. 10 Now as I have said, the applications for the Patents were filed on 13 March 2009. But although ss 7 and 40 of the Patents Act 1990 (Cth) (the Act) were amended by the Intellectual Property Laws Amendment (Raising the Bar) Act 2012 (Cth) (the Raising the Bar Act), the amendments brought about do not affect the present case. 11 Further, each of the 257 Patent and the 258 Patent claim priority from two convention applications being AU2008901223 and AU2008901224 filed on 13 March 2008 (the priority date). There is no issue concerning the priority date. 12 I should note one other preliminary matter. By an interlocutory application dated 13 April 2017, BlueScope has applied to amend the 257 Patent. The amendments sought relate to the description in the body of the 257 Patent, but not the claims. 13 In summary and for the reasons that I have explained in more detail later, I have rejected BlueScope's infringement case even assuming the asserted claims of the 257 Patent and the 258 Patent to be valid. But in any event, the asserted claims of the 257 Patent and some of the asserted claims of the 258 Patent are invalid by reason of the specifications failing to disclose the best method known to BlueScope at the relevant time. Further, I have rejected BlueScope's amendment application relating to the 257 Patent. 14 It is convenient to divide my reasons into the following sections: (a) The 257 Patent - [17] to [81]. (b) The 258 Patent - [82] to [120]. (c) The measurement protocol - [121] to [134]. (d) BlueScope's application of the protocol - [135] to [232]. (e) Deficiencies in the experimental evidence - [233] to [415]. (f) Infringement of the 257 Patent - [416] to [602]. (g) Infringement of the 258 Patent - [603] to [679]. (h) Invalidity - general - [680] to [702]. (i) Lack of clarity and lack of definition - [703] to [747]. (j) Lack of fair basis - [748] to [799]. (k) Lack of sufficiency - [800] to [826]. (l) Lack of disclosure of best method - [827] to [960]. (m) False suggestion - [961] to [1013]. (n) Lack of novelty - [1014] to [1219]. (o) Lack of inventive step - [1220] to [1323]. (p) Amendment application - [1324] to [1513]. (q) Conclusion - [1514] to [1517]. 15 I should say at the outset that I have been much assisted by the technical presentations of all counsel. Their cases were presented with notable efficiency. 16 Let me begin with identifying and describing some of the key features of the 257 Patent and the 258 Patent. I will then turn to questions of infringement before dealing with questions of invalidity. It is convenient to take this course, albeit that this may seem counter-intuitive, in order to achieve some comprehensible flow to the technical issues.

THE 257 PATENT 17 The Patents relate to the field of alloy-coated steel strips, where the alloy coating provides corrosion resistance. The work in this field was undertaken by materials scientists and engineers with a focus on corrosion resistance. In the present case, the person skilled in the art is a team of materials scientists and engineers working in the coatings field, with a particular interest in Al-Zn coatings, who were involved in a research project to identify an improved coating at the priority date. The team would have expertise in hot dip coatings, including galvalume, that is, alloy coatings having 55 wt. % aluminium, 43 wt. % zinc and approximately 1.5 to 2 wt. % silicon. They would have a practical interest in the subject matter of the invention but be presumed to be unimaginative and non-inventive. 18 The invention the subject of the specification of the 257 Patent is described in the following terms (p 1 lines 3 to 36): The present invention relates to strip, typically steel strip, which has a corrosion-resistant metal alloy coating. The present invention relates particularly to a corrosion-resistant metal alloy coating that contains aluminium-zinc-silicon-magnesium as the main elements in the alloy, and is hereinafter referred to as an "Al-Zn-Si-Mg alloy" on this basis. The alloy coating may contain other elements that are present as deliberate alloying additions or as unavoidable impurities. Hence, the phrase "Al-Zn-Si-Mg alloy" is understood to cover alloys that contain such other elements and the other elements may be deliberate alloying additions or as unavoidable impurities. The present invention relates particularly but not exclusively to steel strip that is coated with the above-described Al-Zn-Si-Mg alloy and can be cold formed (e.g. by roll forming) into an end-use product, such as roofing products. Typically, the Al-Zn-Si-Mg alloy comprises the following ranges in % by weight of the elements aluminium, zinc, silicon, and magnesium: Aluminium: 40 to 60 % Zinc: 40 to 60 % Silicon: 0.3 to 3% Magnesium 0.3 to 10 % Typically, the corrosion-resistant metal alloy coating is formed on steel strip by a hot dip coating method. 19 In terms of the addition of silicon and magnesium, the following was said (p 3 line 4 to p 4 line 7): It is known to add silicon to the coating alloy composition to prevent excessive alloying between the steel substrate and the molten coating in the hot-dip coating method. A portion of the silicon takes part in a quaternary alloy layer formation but the majority of the silicon precipitates as needle-like, pure silicon particles during solidification. These needle-like silicon particles are also present in the inter-dendritic regions of the coating. It has been found by the applicant that when Mg is included in a 55%Al-Zn-Si alloy coating composition, Mg brings about certain beneficial effects on product performance, such as improved cut-edge protection, by changing the nature of corrosion products formed. However, it has also been found by the applicant that Mg reacts with Si to form a Mg2Si phase and that the formation of the Mg2Si phase compromises the above-mentioned beneficial effects of Mg in a number of ways. One particular way, which is the focus of the present invention is a surface defect called "mottling". The applicant has found that mottling can occur in Al-Zn-Si-Mg alloy coatings under certain solidification conditions. Mottling is related to the presence of the Mg2Si phase on the coating surface. More particularly, mottling is a defect where a large number of coarse Mg2Si particles cluster together on the surface of the coating, resulting in a blotchy surface appearance that is not acceptable from an aesthetic viewpoint. More particularly, the clustered Mg2Si particles form darker regions approximately 1-5 mm in size and introduce non-uniformity in the appearance of the coating which makes the coated product unsuitable for applications where a uniform appearance is important. The above description is not to be taken as an admission of the common general knowledge in Australia or elsewhere. 20 Then there is a statement of the invention as follows (p 4 lines 9 to 14): The present invention is an Al-Zn-Si-Mg alloy coated strip that has Mg2Si particles in the coating with the distribution of Mg2Si particles being such that a surface of the coating has only a small proportion of Mg2Si particles or is at least substantially free of any Mg2Si particles. 21 As to this statement, what does "small proportion" mean? Almost nothing? And does the phrase "only a small proportion" mean the same thing as "at least substantially free"? And does the latter phrase mean immaterially small? 22 Further, it was then explained (p 4 lines 16 to 27): The applicant has found that the above-described distribution of Mg2Si particles in the coating microstructure provides significant advantages and can be achieved by any one or more of: (a) strontium additions in the coating alloy, (b) selection of the cooling rate during solidification of coated strip for a given coating mass (i.e. coating thickness) exiting a coating bath; and (c) minimising variations in coating thickness. 23 There are two issues to note concerning this passage. Does "can" in the phrase "can be achieved" mean may or must? Further, what is the significance of "any one or more of"? Does this mean that the promise can be achieved with one only? 24 The addition of strontium (Sr) is then explained (p 4 line 29 to p 5 line 12): The applicant has found that Sr additions described in more detail below control the distribution characteristics of the Mg2Si phase in the thickness direction of an Al-Zn-Si-Mg alloy coating so that the surface of the coating has only a small proportion of Mg2Si particles or is at least substantially free of Mg2Si particles, whereby there is a considerably lower risk of Mg2Si mottling. The applicant has found that when at least 250 ppm Sr, preferably 250-3000 ppm Sr, is added to a coating bath containing an Al-Zn-Si-Mg alloy the distribution characteristics of the Mg2Si phase in the coating thickness direction are completely changed by this addition of Sr from the distribution that is present when there is no Sr in the coating bath. Specifically, the applicant has found that these additions of Sr promote the formation of a surface of the coating that has only a small proportion of Mg2Si particles or is free of any Mg2Si particles and consequently a considerably lower risk of mottling on the surface. 25 The reference to "below" (p 4 line 30) appears to be a reference to p 7. Further, are these passages saying that Sr is the cause (i.e. on its own)? 26 In an apparently self-contained passage referring to the subject matter in (b) (p 4 line 23), the following is said (p 5 lines 14 to 23): The applicant has also found that selecting the cooling rate during solidification of a coated strip exiting a coating bath to be below a [threshold] cooling rate, typically below 80℃/sec for coating masses less than 100 grams per square metre of strip surface per side, controls the distribution characteristics of the Mg2Si phase so that the surface has only a small proportion of Mg2Si particles or is at least substantially free of Mg2Si particles, whereby there is a considerably lower risk of Mg2Si mottling. 27 In a yet further apparently self-contained passage referring to the subject matter in (c) (p 4 line 27), the following is said (p 5 lines 25 to 34): The applicant has also found that minimising coating thickness variations controls the distribution characteristics of the Mg2Si phase so that the surface has only a small proportion of Mg2Si particles or is at least substantially free of Mg2Si particles, whereby there is a considerably lower risk of Mg2Si mottling. As is the case with Sr addition and selection of cooling rate during solidification, the resultant coating microstructure is advantageous in terms of appearance, enhanced corrosion resistance and improved coating ductility. 28 Then the invention is described (p 5 line 36 to p 6 line 4): The claims define the invention in terms of minimising coating thickness variations to control the distribution characteristics of the Mg2Si phase so that the surface has only a small proportion of Mg2Si particles or is at least substantially free of Mg2Si particles, whereby there is a considerably lower risk of Mg2Si mottling. 29 Then there are listed consistory clauses (p 6 line 6 to p 9 line 5). 30 The advantages are then described as follows (p 9 lines 6 to 21): The advantages of the invention include the following advantages. • Elimination of mottling defect and improved first-time-prime production rate. The risk of the mottling defect is at least substantially eliminated and the surface of the resultant coating maintains a beautiful, silvery metallic appearance. As a result, first-time-prime production rate is improved and profitability is boosted. • Prevention of mottling defect by the addition of Sr allows the use of higher cooling rates, reducing the length of cooling equipment required after the pot. 31 In terms of line trials the following was said (p 11 line 3 to p 13 line 25): The applicant has also carried out line trials on 55%Al-Zn-1.5%Si-2.0%Mg alloy composition (not containing Sr) coated on steel substrates. The purpose of these trials was to investigate the impact of cooling rates and coating masses on mottling in the surface of the coatings. The trials covered a range of coating masses from 60 to 100 grams per square metre surface per side of strip, with cooling rates up to 90℃/sec. The applicant found two factors that affected the coating microstructure, particularly the distribution of Mg2Si particles in the coatings, in the trials. The first factor is the effect of the cooling rate of the strip exiting the coating bath before completing the coating solidification. The applicant found that controlling the cooling rate makes it possible to avoid mottling. By way of example, the applicant found that for a AZ150 class coating (or 75 grams of coating per square 25 metre surface per side of strip - refer to Australia Standard AS1397-2001), if the cooling rate is greater than 80℃/sec, Mg2Si particles formed on the surface of the coating. In particular, when the cooling rate was greater than 100℃/sec, mottling occurred. The applicant also found that for the same coating it is not desirable that the cooling rate be too low, particularly below 11℃/sec, as in this case the coating develops a defective "bamboo" structure, whereby the zinc-rich phases forms a vertically straight corrosion path from the coating surface to the steel interface, which compromises the corrosion performance of the coating. Therefore, for a AZ150 class coating, under the experimental conditions tested, the cooling rate should be controlled to be in a range of 11-80℃/sec to avoid mottling on the surface. On the other hand, the applicant also found that for a AZ200 class coating, if the cooling rate was greater than 50℃/sec, Mg2Si particles formed on the surface of the coating and mottling occurred. Therefore, for a AZ200 class coating, under the experimental conditions tested, a cooling rate in a range of 11-50℃/sec is desirable. The second important factor found by the applicant is the uniformness of coating thickness across the strip surface. The applicant found that the coating on the strip surface normally had thickness variations that are (a) long range (across the entire strip width, measured by the "weight-strip-weight" method on a 50mm diameter disc) and (b) short range (across every 25 mm length in the strip width direction, measured in the cross-section of the coating under a microscope with 500x magnification). In a production situation, the long range thickness variation is normally regulated to meet the minimum coating mass requirements as defined in relevant national standards. In a production situation, as far is the applicant is aware, there is no regulation for short range thickness variation, as long as the minimum coating mass requirements as defined in relevant national standards are met. However, the applicant found that short range coating thickness variations could be very high, and special operational measures had to be applied to keep the variations under control. It was not uncommon in the experimental work for the coating thickness to change by a factor of two or more over a distance as short as 5 mm, even when the product perfectly met the minimum coating mass requirements as defined in relevant national standards. This short range coating thickness variation had a pronounced impact on the Mg2Si particles in the surface of coatings. By way of example, the applicant found that for a AZ150 class coating even in the desirable cooling rate ranges as described above, if the short range coating thickness variation was greater than 40% above the nominal coating thickness within a distance of 5 mm across the strip surface, Mg2Si particles formed on the surface of the coating and thereby increased the risk of mottling. Therefore, under the experimental conditions tested, the short range coating thickness variation should be controlled to no greater than 40% above the nominal coating thickness within a distance of 5mm across the strip surface to avoid mottling. 32 I will return later to the significance of the phrase "special operational measures" (p 13 line 3). 33 I should also set out some other passages (p 16 line 23 to p 18 line 3): Practically, the applicant has found that, to achieve the distribution of Mg2Si particles of the present invention, i.e. to avoid mottling defect on the surface of a coated strip, the cooling rate for coated strip exiting the coating bath has to be in a range of 11-80℃/sec for coating masses up to 75 grams per square metre of strip surface per side and in a range 11-50℃/sec for coating masses of 75-100 grams per square metre of strip surface per side. The short range coating thickness variation also has to be controlled to be no greater than 40% above the nominal coating thickness within a distance of 5 mm across the strip surface to achieve the distribution of Mg2Si particles of the present invention. The applicant has also found that, when Sr is present in a coating bath, the above described kinetics of Mg2Si nucleation can be significantly influenced. At certain Sr concentration levels, Sr strongly segregates into the quaternary alloy layer (i.e. changes the chemistry of the quaternary alloy phase). Sr also changes the characteristics of surface oxidation of the molten coating, resulting in a thinner surface oxide on the coating surface. Such changes alter significantly the preferential nucleation sites for the Mg2Si phase and, as a result, the distribution pattern of the Mg2Si phase in the coating thickness direction. In particular, the applicant has found that, Sr at concentrations 250-3000ppm in the coating bath makes it virtually impossible for the Mg2Si phase to nucleate on the quaternary alloy layer or on the surface oxide, presumably due to the very high level of increase in system free energy would otherwise be generated. Instead, the Mg2Si phase can only nucleate at the central region of the coating in the thickness direction, resulting in a coating structure that is substantially free of Mg2Si at both the coating outer surface region and the region near the steel surface. Therefore, Sr additions in the range 250-3000ppm are proposed as one of the effective means to achieve a desired distribution of Mg2Si particles in a coating. Many modifications may be made to the present invention as described above without departing from the spirit and scope of the invention. In this context, whilst the above description of the present invention focuses on (a) the addition of Sr to Al-Zn-Si-Mg coating alloys, (b) cooling rates (for a given coating mass) and (c) control of short range coating thickness variation as means for achieving a desired distribution of Mg2Si particles in coatings, i.e. at least substantially no Mg2Si particles in the surface of a coating, the present invention is not so limited and extends to the use of any suitable means to achieve the desired distribution of Mg2Si particles in the coating. 34 The following claims, inter-alia, are then made (pp 19 to 21): 1. A hot-dip coating method for forming a coating of a corrosion-resistant Al-Zn-Si-Mg alloy on a steel strip comprising passing the steel strip through a hot dip coating bath that contains Al, Zn, Si, and Mg and optionally other elements and forming an alloy coating on the strip with a variation in thickness of the coating of no more than 40% in any given 5 mm diameter section so that the distribution of Mg2Si particles in the coating microstructure is such that there is only a small proportion of Mg2Si particles or substantially no Mg2Si particles in the surface of the coating. … 3. The method defined in any one of the preceding claims wherein the small proportion of Mg2Si particles in the surface of the coating is no more than 10wt.% of the Mg2Si particles. 4. The method defined in any one of the preceding claims wherein the coating thickness variation is no more than 30% in any given 5 mm diameter section of the coating. 5. The method defined in any one of the preceding claims wherein, for a coating thickness of 22μm, the maximum thickness in any region of the coating greater than 1mm in diameter is 27μm. 6. The method defined in any one of the preceding claims comprising selecting the cooling rate during solidification of coated strip exiting the coating bath to be less than a threshold cooling rate. … 8. The method defined any one of claims 1 to 6 comprising selecting the cooling rate for coated strip exiting the coating bath to be less than 50℃/sec for coating masses of 75-100 grams per square metre of strip surface per side. 9. The method defined in any one of the preceding claims wherein the coating comprises the following ranges in % by weight of the elements aluminium, zinc, silicon, and magnesium: Aluminium: 40 to 60 % Zinc: 40 to 60 % Silicon: 0.3 to 3% Magnesium 0.3 to 10 %. … 11. The method defined in any one of the preceding claims wherein the coating contains less than 3000 ppm Sr. 12. The method defined in any one of the preceding claims comprising forming the coating to have a thickness of less than 30μm. 13. The method defined in any one of the preceding claims comprising forming the coating to have a thickness 35 of greater than 7μm. 14. A steel strip having a coating of a corrosion-resistant Al-Zn-Si-Mg alloy formed by the method defined in any one of the preceding claims. 15. An Al-Zn-Si-Mg alloy coated strip that has Mg2Si particles in the coating with the distribution of Mg2Si particles being such that a surface of the coating has only a small proportion of Mg2Si particles or is at least substantially free of any Mg2Si particles formed by the method defined in any one of the preceding claims. 35 It will be apparent that claim 1 is the only truly independent claim. 36 Let me summarise some of the aspects of the specification. 37 The specification explains that the invention relates to strip, typically steel strip, which has a corrosion-resistant metal alloy coating and more particularly a corrosion-resistant metal alloy coating that contains as its main elements aluminium, zinc, silicon and magnesium being an Al-Zn-Si-Mg alloy. 38 The specification observes that the alloy coating may contain other elements that are present as deliberate alloying additions or unavoidable impurities. The specification explains that the expression "an Al-Zn-Si-Mg alloy" is to be understood as covering an Al-Zn-Si-Mg alloy which also includes other elements. 39 The specification explains that the present invention relates to steel strip that is coated with the Al-Zn-Si-Mg alloy and can be cold formed into an end-use product such as roofing products. 40 The specification explains that typically the Al-Zn-Si-Mg alloy comprises 40 to 60% weight of Al, 40 to 60% weight Zn, 0.3 to 3% Si and 0.3 to 10% Mg and that typically the metal alloy coating is formed by a hot dip coating method. 41 After explaining the conventional hot dip coating method, the specification explains that a 55%Al-Zn alloy coating that is sold under the name "galvalume" is a well known metal alloy coating for steel strip, and that after solidification, such a coating normally consists of Al dendrites that are a characteristic tree-like structure of Al crystals, and a Zn phase in the inter-dendritic regions that is the region or space between the Al dendrites. The specification explains that it is known to add Si to prevent excessive alloying between the steel substrate and the molten coating. But only a portion of Si takes part in the quaternary alloy layer formation. The majority of Si precipitates as needle-like pure Si particles. The needle-like Si particles are also present in the inter-dendritic regions of the coating. 42 At this point I note that a 55% Al-Zn alloy coating was a coating originally developed by Bethlehem Steel in the United States in the 1960s and known there as "galvalume" and in Australia as "galvalume" or "zincalume". BlueScope and its predecessors produced that product in Australia under licence for many years before the priority date. 43 As I have already indicated, the specification states that the applicant has found that when Mg is included in a 55%Al-Zn-Si alloy coating composition, it brings about certain beneficial effects on product performance, such as improved cut-edge protection, by changing the nature of the corrosion products formed. However, it was also found that the Mg reacts with Si to form an Mg2Si phase which compromises the beneficial effects of Mg in a number of ways. 44 One of the consequences of the Mg2Si phase being formed is a surface defect called "mottling". This can occur in Al-Zn-Si-Mg alloy coatings under certain solidification conditions and is related to the presence of an Mg2Si phase on the surface of the coating. The specification explains that mottling occurs where a large number of coarse Mg2Si particles cluster together on the surface of the coating, resulting in a blotchy and aesthetically unacceptable surface. The clustered Mg2Si particles form darker regions from 1 to 5 mm in size and introduce non-uniformity in the appearance of the coating. 45 The specification identifies the present invention as an Al-Zn-Si-Mg alloy coated strip that has Mg2Si particles in the coating with the distribution of Mg2Si particles being such that a surface of the coating has only a small proportion of Mg2Si or is at least substantially free of Mg2Si particles. 46 The specification explains that the applicant has found that such a distribution of Mg2Si particles in the coating microstructure provides significant advantages in terms of appearance, enhanced corrosion resistance and improved coating ductility (p 5 lines 33 to 34). As I have indicated, it states (p 4 lines 16 to 28) that those advantages can be achieved by any one or more of: (a) adding Sr in the coating alloy; (b) selection of the cooling rate for the coated strip for a given coating mass as it exits the coating bath; and (c) minimising variations in coating thickness. 47 BlueScope submits that the use of the word "can" is permissive, when read in context. So, it means "may" rather than "will". I agree. 48 Further, BlueScope says that the proper construction of the phrase "any one or more" does not mean that if a skilled addressee practices one of the trilogy of matters set out in (a), (b) or (c) above in isolation, it will inevitably give rise to the requisite distribution of Mg2Si. It says that the specification makes it plain that where the claimed cooling rate is used, it is also necessary to control coating thickness variation. Generally speaking I agree with BlueScope's construction. Its construction is supported by various passages of the specification some of which I have set out earlier. It is convenient to identify them as follows: By way of example, the applicant found that for a AZ150 class coating even in the desirable cooling rate ranges as described above, if the short range coating thickness variation was greater than 40% above the nominal coating thickness within a distance of 5mm across the strip surface, Mg2Si particles formed on the surface of the coating and thereby increased the risk of mottling. (page 13 lines 13 to 19) … In particular, the applicant has found that for a set coating thickness, the cooling rate should be regulated to a particular range, and more particularly not to exceed a threshold temperature, to avoid the risk for the Mg2Si phase to nucleate in region A. (page 16 lines 1 to 5) … Practically, the applicant has found that, to achieve the distribution of Mg2Si particles of the present invention, i.e. to avoid mottling defect on the surface of a coated strip, the cooling rate for coated strip exiting the coating bath has to be in a range of 11-80°C/sec for coating masses up to 75 grams per square metre of strip surface per side and in a range 11-50°C/sec for coating masses of 75-100 grams per square metre of strip surface per side. The short range coating thickness variation also has to be controlled to be no greater than 40% above the nominal coating thickness within a distance of 5mm across the strip surface to achieve the distribution of Mg2Si particles of the present invention. (page 16 lines 23 to 35) 49 In relation to the addition of Sr, BlueScope refers to p 17 lines 1 to 17 of the specification and says that this passage says that Sr can also have an effect, but not that it can occur in isolation. Again, generally speaking I agree with BlueScope's construction. 50 Further, it seems to me that the relevant passages indicate that it may be necessary to combine the trilogy to achieve the desired distribution of Mg2Si particles resulting in a product that is mottle-defect free. 51 It seems to me, as BlueScope correctly submitted, that the three methods referred to above control the distribution characteristics of the Mg2Si phase so that the surface has only a small proportion of Mg2Si particles or is at least substantially free of Mg2Si particles, resulting in a considerably lower risk of Mg2Si mottling. 52 Let me proceed further with the specification. As I have set out earlier, the specification goes on (at p 5 lines 1 to 3) to describe the addition of Sr and notes that the applicant has found that the desired distribution of Mg2Si is obtained when at least 250 ppm Sr is added to the coating bath. 53 The specification then explains how keeping the cooling rate below a certain threshold for a given coating mass can control the Mg2Si distribution. 54 The specification then describes that the applicant has found that minimising coating thickness variations also controls the distribution characteristics of the Mg2Si phase. 55 As I have indicated earlier, the specification then states (at p 5 lines 36 to 37 and p 6 lines 1 to 4) that "[t]he claims define the invention in terms of minimising coating thickness variations" to obtain the desired distribution of Mg2Si. Then there is a consistory clause corresponding to claim 1 followed by consistory clauses broadly corresponding to dependent claims. All of the claims involve minimising coating thickness variations and certain of the dependent claims also involve either Sr additions or selection of cooling rate. 56 The specification then recites the aspect of the invention which is the subject of claim 1 (p 6 lines 6 to 17). The specification then recites preferred aspects of the method which are reflected in dependent claims 2 to 14 (p 6 line 19 to p 8 line 25). The specification goes on to explain that the invention also relates to a steel strip which is formed by the earlier described method of the invention. 57 The specification then outlines the advantages of the invention, which include the following as I have already indicated (p 9 lines 9 to 22). 58 First, it is said that one advantage is that the risk of the mottling defect is at least substantially eliminated and the surface of the coating retains a beautiful, silvery metallic appearance, improving first-time-prime production rate and profitability. 59 Second, it is said that another advantage is that the addition of Sr to prevent mottling allows the use of higher cooling rates, reducing the length of cooling equipment required after the pot. 60 The specification then discloses laboratory experiments on a series of 55% Al, 1.5% Si, 2.0% Mg with the remainder Zn alloy compositions, being an alloy composition including 41.5% Zn, having up to 3000 ppm Sr. The purpose of the experiments was to investigate the impact of Sr on mottling (p 9 lines 30 to 32). The specification states that alloys without Sr have Mg2Si particles distributed throughout, whereas alloys with 250 ppm to 3000 ppm Sr have upper and lower regions at the coating surface and at the interface of the steel substrate that are free of Mg2Si (p 9 line 25 to p 10 line 35). 61 Reference is also made to figure 1 which shows photomicrographs of a coating without Sr and a coating with Sr and it is noted that the alloy to which 500 ppm of Sr was added demonstrates "[a] complete absence of mottling". 62 At p 10 lines 32 to 35 it is said: The laboratory experiments found that the microstructure shown in the right hand side of the Figure were formed with Sr additions in the range of 250-3000 ppm. 63 Dongkuk notes that there is no suggestion that Sr additions below 250 ppm had any beneficial effect on Mg2Si distribution. 64 As I have indicated earlier, the specification describes line trials of 55% Al, 1.5% Si, 2.0% Mg with the remainder Zn alloy compositions that did not contain Sr. The specification reports that the applicant found there to be two factors that particularly affected the distribution of Mg2Si (p 11 lines 1 to 15). The first factor is cooling rate (p 11 lines 16 to 21). The second factor is the uniformity of the coating thickness across the surface of the strip (p 12 lines 18 to 20). 65 Dongkuk says that this first factor is consistent with the three alternative methods of achieving the desired distribution of Mg2Si set out at p 4 lines 16 to 27 and set out above. 66 According to Dongkuk, the specification then goes on to say, at p 11 lines 23 to 36 and p 12 lines 1 to 2, which I have set out earlier: By way of example, the applicant found that for a AZ150 class coating (or 75 grams of coating per square metre surface per side of strip - refer to Australia Standard AS1397-2001), if the cooling rate is greater than 80°C/sec, Mg2Si particles formed on the surface of the coating. In particular, when the cooling rate was greater than 100°C/sec, mottling occurred. The applicant also found that for the same coating it is not desirable that the cooling rate be too low, particularly below 11°C/sec, as in this case the coating develops a defective "bamboo" structure, whereby the zinc-rich phases forms a vertically straight corrosion path from the coating surface to the steel interface, which compromises the corrosion performance of the coating. 67 The patentee is telling the person skilled in the art that for an AZ150 class coating (i.e. up to 75 grams per square metre of strip surface per side) if the cooling rate is kept at a rate below 80°C per second, Mg2Si particles will not form on the surface of the coating. The patentee is also telling the person skilled in the art not to use a cooling rate below 11°C per second for different reasons. 68 The specification then goes on at p 12 to make similar observations in respect of AZ200 class coating, that is, 100 grams per square metre of strip surface per side, and indicates that the cooling rate should be kept at a rate between 11 to 50°C per second. So, the thicker the coating the lower the cooling rate. 69 The specification then describes the second factor affecting Mg2Si distribution (at p 12 lines 18 to 20): The second important factor found by the applicant is the uniformness of coating thickness across the strip surface. 70 The specification describes the uniformity of the coating thickness across the strip surface. The specification explains that the coating had long range thickness variations across the entire strip width and short range thickness variations (p 12 lines 22 to 28). The specification explains that in a production situation short range thickness variation was not regulated so long as minimum coating mass requirements were met as defined in national standards (p 12 lines 32 to 36). However, short range coating thickness variations could be very high (p 13 lines 1 to 2). It was not uncommon in the experimental work for the coating thickness to change by a factor of two or more over a distance as short as 5 mm, even where it met minimum coating mass requirements (p 13 lines 4 to 9). This variation had a pronounced impact on Mg2Si particles (p 13 lines 9 and 10). But unlike short range thickness variations, long range thickness variations were measured by the weigh-strip-weigh method (p 12 lines 24 and 25); I will use "weigh-strip-weigh" rather than "weight-strip-weight". The specification explains (p 13 lines 13 to 25): By way of example, the applicant found that for a AZ150 class coating even in the desirable cooling rate ranges as described above, if the short range coating thickness variation was greater than 40% above the nominal coating thickness within a distance of 5 mm across the strip surface, Mg2Si particles formed on the surface of the coating and thereby increased the risk of mottling. Therefore, under the experimental conditions tested, the short range coating thickness variation should be controlled to no greater than 40% above the nominal coating thickness within a distance of 5mm across the strip surface to avoid mottling. 71 The specification says that it was found that short range coating thickness variations could be very high and special operational measures had to be applied to keep the variations under control. It is said (at p 13 lines 1 to 11): However, the applicant found that short range coating thickness variations could be very high, and special operational measures had to be applied to keep the variations under control. It was not uncommon in the experimental work for the coating thickness to change by a factor of two or more over a distance as short as 5 mm, even when the product perfectly met the minimum coating mass requirements as defined in relevant national standards. This short range coating thickness variation had a pronounced impact on the Mg2Si particles in the surface of coatings. 72 It is then said (at p 13 lines 13 to 19): By way of example, the applicant found that for a AZ150 class coating even in the desirable cooling rate ranges as described above, if short range coating thickness variation was greater than 40% above the nominal coating thickness within a distance of 5 mm across the strip surface, Mg2Si particles formed on the surface of the coating and thereby increased the risk of mottling. 73 Dongkuk says that there is an inconsistency between the above paragraph and the assertion that is made on p 4 line 23 that "selection of the cooling rate during solidification of coated strip for a given coating mass (i.e. coating thickness) exiting a coating bath" alone can achieve the desired distribution of Mg2Si particles. One way to resolve this inconsistency is to understand the expression "even in the desirable cooling rate ranges as described above" not to mean the whole extent of the ranges described above, but, rather, the end of those ranges. Thus, for an AZ150 class coating, if the cooling rate approaches the 80°C per second point, there may be a need to control thickness variation. 74 Dongkuk says that the specification then advances a theory as to why cooling rates for certain thicknesses can influence the distribution of Mg2Si. In substance the theory is that Mg2Si particles tend to move from the surface of the alloy coating to the centre of the alloy coating before they begin to solidify, but if the cooling rate is too high for the distance which needs to be travelled, those particles will solidify at or near the surface before they can reach the centre. 75 The specification then says at p 16 lines 23 to 35: Practically, the applicant has found that, to achieve the distribution of Mg2Si particles of the present invention, i.e. to avoid mottling defect on the surface of a coated strip, the cooling rate for coated strip exiting the coating bath has to be in a range of 11-80°C/sec for coating masses up to 75 grams per square metre of strip surface per side and in a range 11-50°C/sec for coating masses of 75-100 grams per square metre of strip surface per side. The short range coating thickness variation also has to be controlled to be no greater than 40% above the nominal coating thickness within a distance of 5 mm across the strip surface to achieve the distribution of Mg2Si particles of the present invention. 76 Again Dongkuk says that there is an inconsistency between this passage and the passage at p 4 lines 16 to 27. 77 The specification then goes on to describe how Sr achieves the desired Mg2Si distribution. In substance Sr brings about a chemical effect which makes it less desirable for Mg2Si to nucleate at the surface of the alloy coating. 78 In summary, the specification explains that it has been found that to achieve a distribution of Mg2Si particles that substantially eliminates mottling, various things are important. 79 First, the cooling rate for the coated strip exiting the coating bath has to be in the range of 11 to 80°C/sec for coating masses up to 75 grams per square metre of strip surface per side. Further, the cooling rate has to be in the range of 11 to 50°C/sec for coating masses of 75 to 100 grams per square metre of strip surface per side. 80 Second, the short range coating thickness variation has to be controlled so that it is no greater than 40% above the nominal coating thickness within a distance of 5 mm across the strip surface to achieve the distribution of Mg2Si particles of the present invention. The specification describes minimising coating thickness variations. Specifically, the specification describes a variation in thickness of the coating of no more than 40% in any given 5mm diameter section or no more than 30% in any given 5mm diameter section. In any given situation the selection of an appropriate thickness variation will be related to the coating thickness or coating mass. 81 Third, as to the addition of Sr, the specification describes the addition of 250 to 3000 ppm of Sr. The specification explains that the inclusion of Sr in the coating bath can affect the kinetics of Mg2Si nucleation because Sr changes the chemistry of the quaternary alloy layer and the characteristics of surface oxidation. But the specification does not suggest that the inclusion of Sr affects coating thickness variation.

THE 258 PATENT 82 The 258 Patent deals with both product claims (claims 1 to 12) and method claims (claims 13 to 25). The first two and a half pages of the specification are similar to the 257 Patent specification, but then there are some differences. 83 The specification does not address mottling. Rather, it is said (p 3 line 25 to p 14 line 15): By way of example, the Mg2Si phase forms as large particles in relation to typical coating thicknesses and can provide a path for rapid corrosion where particles extend from a coating surface to an alloy layer adjacent the steel strip. By way of further example, the Mg2Si particles tend to be brittle and sharp particles and provide both an initiation and propagation path for cracks that form on bending of coated products formed from coated strip. Increased cracking compared to Mg-free coatings can result in more rapid corrosion of the coatings. The above description is not to be taken as an admission of the common general knowledge in Australia or elsewhere. The present invention is an Al-Zn-Si-Mg alloy coated strip that has Mg2Si particles in the coating microstructure with the distribution of Mg2Si particles being such that a surface region of the coating has only a small proportion of Mg2Si particles or is at least substantially free of any Mg2Si particles. The term "surface region" is understood herein to mean a region that extends inwardly from the exposed surface of a coating. 84 So, ductility rather than the problem with mottling seems to be the issue. 85 The statement of the invention (at p 4 line 5) is also slightly different to that of the 257 Patent. It is said: The present invention is an Al-Zn-Si-Mg alloy coated strip that has Mg2Si particles in the coating microstructure with the distribution of Mg2Si particles being such that a surface region of the coating has only a small proportion of Mg2Si particles or is at least substantially free of any Mg2Si particles. 86 The specification goes on: The term "surface region" is understood herein to mean a region that extends inwardly from the exposed surface of a coating. 87 The specification then repeats the passage of the 257 Patent set out earlier (p 4 lines 16 to 27). It says that the desired distribution of Mg2Si can be achieved by Sr additions, selection of cooling rate, and minimising variations in coating thickness. 88 The specification then provides a consistory clause in the terms of claim 1. It says: According to the present invention there is provided an Al-Zn-Si-Mg alloy coated steel strip that comprises a coating of an Al-Zn-Si-Mg alloy on a steel strip with the alloy comprising in % by weight 40 to 60% Al, 40 to 60% Zn, 0.3 to 3% Si, and 0.3 to 10% Mg and unavoidable impurities, with the microstructure of the coating comprising Mg2Si particles, and with the distribution of the Mg2Si particles being such that there is no more than 10% by weight of Mg2Si particles in a surface region of the coating that has a thickness that is less than 30% of the total thickness of the coating. 89 So, the invention is said to be a coated steel strip with an alloy coating having the same components in the same ranges as claim 9 of the 257 Patent but the difference is that the distribution of Mg2Si particles is such that the surface region, that is the region below the surface itself, is "substantially free" of Mg2Si particles. 90 Consistently with the above there are also separate consistory clauses for each means whereby the desired distribution of Mg2Si particles is achieved. 91 The specification sets out the advantages of the invention (p 9 line 16 to p 10 line 23). The first advantage is said to be: Enhanced corrosion resistance. The Mg2Si distribution of the present invention eliminates direct corrosion channels from the coating surface to steel strip that occurs with a conventional Mg2Si distribution. As a result, the corrosion resistance of the coating is markedly enhanced. 92 The next advantage is said to be improved coating ductility. 93 The third advantage is said to be as follows: The addition of Sr allows the use of higher cooling rates, reducing the length of cooling equipment required after the pot. 94 The Sr addition experiments are identical to those described in the 257 Patent. They illustrate the effect on Mg2Si distribution with the addition of Sr. 95 Further, there is a discussion of line trials. So at p 12 lines 1 to 27 the following was said: The applicant has also carried out line trials on 55%Al-Zn-1.5%Si-2.0%Mg alloy composition (not containing Sr) coated on steel strip. The purpose of these trials was to investigate the impact of cooling rates and coating masses on the distribution of Mg2Si particles in the coatings. The experiments covered a range of coating masses from 60 to 100 grams per square metre surface per side of strip, with cooling rates up to 90℃/sec. The applicant found two factors that affected the coating microstructure, particularly the distribution of Mg2Si particles in the coatings. The first factor is the effect of the cooling rate of the strip exiting the coating bath before completing the coating solidification. The applicant found that controlling the cooling rate is important. By way of example, the applicant found that for a AZ150 class coating (or 75 grams of coating per square metre surface per side of strip - refer to Australia Standard AS1397-2001), if the cooling rate is greater than 80℃/sec, Mg2Si particles formed in the surface region of the coating. 96 There is no reference to mottling. 97 It is also said: The applicant also found that for the same coating it is not desirable that the cooling rate be too low, particularly below 11°C/sec, as in this case the coating develops a defective "bamboo" structure, whereby the zinc-rich phases forms a vertically straight corrosion path from the coating surface to the steel interface, which compromises the corrosion performance of the coating. 98 The specification is saying that for an AZ150 class coating, that is, up to 75 grams per square metre of strip surface per side, if the cooling rate is kept at a rate below 80°C per second, Mg2Si particles will not form in the surface region. The specification is saying not to use a cooling rate below 11°C per second for different reasons. The specification then goes on to make similar observations in respect of AZ200 class coating (i.e. 75 to 100 grams per square metre of strip surface per side), and indicates that the cooling rate should be kept at a rate between 11 and 50°C per second. 99 Page 12 and the first half of p 13 are relevantly the same as for the 257 Patent, but p 13, line 15 of the 258 Patent does not discuss "the second factor", thickness variation, as the 257 Patent does. Rather, at this point it discusses the BlueScope research work in substantially the same terms as the 257 Patent. 100 Later it is said (p 16 line 8 to p 17 line 24): Practically, the applicant has found that, to achieve the distribution of Mg2Si particles of the present invention, i.e. to avoid nucleation of the Mg2Si phase in region A, the cooling rate for coated strip exiting the coating bath has to be in a range of 11-80℃/sec for coating masses up to 75 grams per square metre of strip surface per side and in a range 11-50℃/sec for coating masses of 75-100 grams per square metre of strip surface per side. The short range coating thickness variation also has to be controlled to be no greater than 40% above the nominal coating thickness within a distance of 5 mm across the strip surface to achieve the distribution of Mg2Si particles of the present invention. The applicant has also found that, when Sr is present in a coating bath, the above described kinetics of Mg2Si nucleation can be significantly influenced. At certain Sr concentration levels, Sr strongly segregates into the quaternary alloy layer (i.e. changes the chemistry of the quaternary alloy phase). Sr also changes the characteristics of surface oxidation of the molten coating, resulting in a thinner surface oxide on the coating surface. Such changes alter significantly the preferential nucleation sites for the Mg2Si phase and, as a result, the distribution pattern of the Mg2Si phase in the coating thickness direction. In particular, the applicant has found that, Sr at concentrations 250-3000ppm in the coating bath makes it virtually impossible for the Mg2Si phase to nucleate on the quaternary alloy layer or on the surface oxide, presumably due to the very high level of increase in system free energy would otherwise be generated. Instead, the Mg2Si phase can only nucleate at the central region of the coating in the thickness direction, resulting in a coating structure that is substantially free of Mg2Si at both the coating outer surface region and the region near the steel surface. Therefore, Sr additions in the range 250-3000ppm are proposed as one of the effective means to achieve a desired distribution of Mg2Si particles in a coating. Many modifications may be made to the present invention as described above without departing from the spirit and scope of the invention. In this context, whilst the above description of the present invention focuses on (a) the addition of Sr to Al-Zn-Si-Mg coating alloys, (b) regulating cooling rates (for a given coating mass) and (c) minimising variations in coating thickness as means for achieving a desired distribution of Mg2Si particles in coatings, i.e. at least substantially no Mg2Si particles in the surface of a coating, the present invention is not so limited and extends to the use of any suitable means to achieve the desired distribution of Mg2Si particles in the coating. 101 The passage at p 16 lines 8 to 20 is equivalent to that set out earlier for the 257 Patent (p 16 lines 23 to 35). 102 The specification ends with 25 claims. All claims are dependent upon claim 1. Claims 1 to 12 are product claims and claims 13 to 25 are method claims. 103 I should set out some of the claims: 1. An Al-Zn-Si-Mg alloy coated steel strip that comprises a coating of an Al-Zn-Si-Mg alloy on a steel strip with the alloy comprising in % by weight 40 to 60% Al, 40 to 60% Zn, 0.3 to 3% Si, and 0.3 to 10% Mg and unavoidable impurities, with the microstructure of the coating comprising Mg2Si particles, and with the distribution of the Mg2Si particles being such that there is no more than 10% by weight of Mg2Si particles in a surface region of the coating that has a thickness that is less than 30% of the total thickness of the coating. 2. The alloy coated steel strip defined in claim 1 wherein the surface region has a thickness that is at least 5% of the total thickness of the coating. … 5. The alloy coated steel strip defined in any one of the preceding claims wherein the coating thickness is less than 30μm. 6. The alloy coated steel strip defined in any one of the preceding claims wherein the coating thickness is greater than 7μm. … 11. The alloy coated steel strip defined in any one of the preceding claims wherein the coating contains less than 3000 ppm Sr. 12. The alloy coated steel strip defined in any one of the preceding claims wherein there are minimal coating thickness variations. … 17. A hot-dip coating method for forming a coating of a corrosion-resistant Al-Zn-Si-Mg alloy on a steel strip as defined in any one of claims 1 to 12 that is characterised by passing the steel strip through a hot dip coating bath that contains Al, Zn, Si, and Mg and optionally other elements and forming an alloy coating on the strip, and cooling coated strip exiting the coating bath during solidification of the coating at a rate that is controlled so that the distribution of Mg2Si particles in the coating microstructure is such that there is no more than 10% by weight of Mg2Si particles in a surface region of the coating that has a thickness that is less than 30% of the total thickness of the coating. 18. The method defined in claim 17 comprises selecting the cooling rate for coated strip exiting the coating bath to be at less than a threshold cooling rate. … 20. The method defined in any one of claims 17 to 19 comprises selecting the cooling rate for coated strip exiting the coating bath to be less than 50℃/sec for coating masses 75-100 grams per square metre of strip surface per side. 21. The method defined in any one of claims 17 to 20 comprises selecting the cooling rate for coated strip exiting the coating bath to at least 11℃/sec. 22. A hot-dip coating method for forming a coating of a corrosion-resistant Al-Zn-Si-Mg alloy on a steel strip as defined in any one of claims 1 to 12 that is characterised by passing the steel strip through a hot dip coating bath that contains Al, Zn, Si, and Mg and optionally other elements and forming an alloy coating on the strip with minimal variation in the thickness of the coating so that the distribution of Mg2Si particles in the coating microstructure is such that there is no more than 10% by weight of Mg2Si particles in a surface region of the coating that has a thickness that is less than 30% of the total thickness of the coating. 23. The method defined in claim 22 wherein the coating thickness variation is no more than 40% in any given 5 mm diameter section of the coating. 24. The method defined in claim 22 or claim 23 wherein the coating thickness variation is no more than 30% in any given 5 mm diameter section of the coating. 25. The method defined in any one of claims 22 to 24 comprises selecting the cooling rate during solidification of coated strip exiting the coating bath to be less than a threshold cooling rate. 104 Again, let me summarise some key themes. 105 The field of technology to which the specification relates is also a strip, typically steel strip, which has a corrosion-resistant metal alloy coating, and particularly a corrosion-resistant metal alloy coating that contains Al, Zn, Si and Mg as its main elements being an Al-Zn-Si-Mg alloy. 106 The specification describes the background to the invention in the same terms as the 257 Patent specification. But whereas the 257 Patent specification focuses on the surface defect "mottling", the 258 Patent specification focuses on improved corrosion resistance performance and overcoming formability problems. 107 The specification is directed to keeping Mg2Si particles away from a "surface region" of the coating and within the central part of the coating. It explains the detrimental effects of Mg2Si particles on the corrosion resistance and formability of coated strip products. 108 The specification explains that with typical coating thicknesses, the Mg2Si phase forms as large particles which can provide a path for rapid corrosion where the particles extend from the surface of the coating to an alloy layer adjacent the steel strip. Further, the Mg2Si particles tend to be brittle and sharp particles, and provide both an initiation site and propagation path for cracks that form on the bending of coated products formed from coated strip. Moreover, increased cracking compared to Mg-free coatings can result in more rapid corrosion of the coatings. 109 The specification explains that the invention is an Al-Zn-Si-Mg alloy coated strip that has Mg2Si particles in the coating microstructure with the distribution of Mg2Si particles being such that a surface region of the coating has only a small proportion of Mg2Si particles or is at least substantially free of any Mg2Si particles. It explains that the term "surface region" should be understood to mean a region that extends inwardly from the exposed surface of a coating. 110 The specification states that the coated steel strip of the invention has a distribution of Mg2Si particles such that there is no more than 10% by weight of Mg2Si particles in the surface region of the coating. The surface region of the coating is to have a thickness which is at least 5% and less than 30% of the total thickness of the coating. 111 The specification explains that the applicant has found that such a distribution of Mg2Si particles in the coating microstructure provides significant advantages. Further, those advantages can be achieved by the three techniques described. 112 The specification lists other preferred aspects of the invention. 113 The specification states that there is also provided a hot dip coating method for forming a coating of a corrosion-resistant Al-Zn-Si-Mg alloy on a steel strip as defined in any one of claims 1 to 12 that is characterised by passing the steel strip through a hot dip coating bath that contains Al, Zn, Si, Mg, and more than 250 ppm Sr and optionally other elements, and forming an alloy coating on the strip that has Mg2Si particles in the coating microstructure with the distribution of the Mg2Si particles being such that there is no more than 10% by weight of Mg2Si particles in a surface region of the coating that has a thickness that is less than 30% of the total thickness of the coating. 114 Further, after listing other preferred aspects of the invention, the specification states that the Al-Zn-Si-Mg-Sr alloy coating may contain other elements as deliberate additions or as unavoidable impurities. 115 Further, after detailing possible coating thickness variations, the specification explains that in any given situation, the selection of an appropriate thickness variation is related to the coating thickness or coating mass. 116 The specification identifies various advantages (p 10 lines 1 to 23) as I have indicated earlier. 117 The specification describes laboratory experiments which showed that the addition of 500 ppm Sr to the alloy had the result that Mg2Si was confined to a central band of the coating. The specification later explains that Sr at concentrations in the range 250 to 3000ppm in the coating bath significantly influences nucleation of Mg2Si and makes it "virtually impossible" for the Mg2Si phase to nucleate on the quaternary alloy layer or on the surface oxide. 118 The specification also details the same line trials as described in the 257 Patent specification, which showed that the cooling rate of the strip, which should be from 11 to 80°C/sec for AZ150 class coatings and 11 to 50°C/sec for AZ200 class coatings, affects the microstructure. 119 The specification concludes by saying that to achieve the distribution of Mg2Si particles of the invention, specified cooling rates must be used and the short range coating thickness variation must be controlled to be no greater than 40% above the nominal coating thickness within a distance of 5 mm across the strip surface. Moreover, the specification states that the inclusion of Sr can influence the kinetics of Mg2Si by changing the chemistry of the quaternary alloy layer and characteristics of surface oxidation, and thereby the distribution pattern of the Mg2Si phase, particularly at concentrations of 250 ppm to 3000 ppm. 120 Let me now turn to the infringement question. As I have said, it is convenient to deal with this before invalidity questions.

MEASUREMENT PROTOCOL 121 It is appropriate to set out as the starting point for the analysis concerning infringement the measurement protocol used by BlueScope which was applied to the GLX product. Parts of two A4 size samples of the GLX product which had been provided to BlueScope by Dongkuk in March 2016 were used. 122 The facts that were sought to be proved by applying the protocol to parts of the March 2016 samples were: (a) the proportion of the surface area of the March 2016 samples that comprised exposed Mg2Si particles; (b) the proportion by weight of Mg2Si particles in the coating microstructure of the March 2016 samples that were exposed at the surface of the coating; (c) the proportion by weight of Mg2Si particles in the coating microstructure of the March 2016 samples that were present in the top 5% of the thickness of the coating; (d) the average, minimum and maximum coating thickness of the March 2016 samples; and (e) the average, minimum and maximum coating thickness of 5mm diameter sections of the March 2016 samples. 123 The protocol reproduced images of portions of the March 2016 samples that remained following other testing that BlueScope had conducted on the samples as set out in Figure 1. The discs and cross-sections which are noted in red in Figure 1 are the approximate locations of where the discs were to be punched and the cross-sections sheared in accordance with the protocol. Figure 1: Location of discs and cross sections from the March 2016 samples. 124 The protocol used the notation of "sample A" and "sample B" to refer to the samples of the March 2016 samples marked as such in Figure 1. 125 Stage 1 being sample preparation involved the following steps: (a) Using a scribe, a 50mm diameter circle was to be marked near the centre of samples A and B as depicted in Figure 1 being the intended punch locations. (b) Using a scribe, each 50mm diameter circle was to be marked with the sample name (either sample A or sample B) and the side (either top or reverse), as depicted in Figure 1. (c) After the samples had been labelled, the labelled 50mm diameter circles were to be punched from each sample. (d) Each disc was to be sheared in half as indicated by the red, dotted, horizontal line in Figure 1, maintaining the labels on each half. The sample was to be trimmed, if necessary, to ensure the sample was properly located on the Electron Probe Microanalyzer (EPMA) to be used at the relevant stage. All burs were to be removed. (e) One 10mm slice was to be sheared across the full strip width of samples A and B, and cut into 30mm lengths (for 40mm diameter mounts) as indicated in Figure 1 in preparation for metallographic mounting and polishing of the 30mm long edge. (f) Each 30×10mm section was to be placed into a separate contamination free plastic bag and the section location was to be recorded on each bag. 126 Stage 2 being to assess the Mg2Si surface presence or elemental surface mapping involved the following steps: (a) A Jeol JXA-8530FPlus HyperProbe Electron Probe Microanalyzer (FE-EPMA) was to be used. (b) For each half (top and reverse) of the two 50mm diameter discs, four separate areas were to be mapped, selected randomly but spaced at least 10mm apart. (c) Each area mapped was to be 500x500µm, at a resolution of 1µm per pixel, using a beam dwell time of 50 milliseconds [the original protocol incorrectly referred to mm rather than µm]. (d) The maps were to be generated using electron beam settings of 5kV for the accelerating voltage and a beam current setting of 50 nanoAmps. This accelerating voltage and beam current setting were to be used throughout the experiment for all FE-EPMA analysis to ensure that the FE-EPMA analysis was not affected by using different parameters. The parameters used for each FE-EPMA analysis were to be recorded. (e) The elemental maps for Mg, Si, Zn were to be measured by wavelength dispersive spectroscopy and captured as separate grey scale images. (f) The characteristic x-rays and spectrometer crystals to be used for each element were: Mg: Kα on TAPH crystal, Zn: Lα on TAPH crystal and Si: Kα on TAP crystal. (g) A professional grade photo editing software tool, such as COREL Paint Shop Pro, was to be used to convert each grey scale elemental map to a colour and each map was to be saved as a separate file. (h) The following colours and settings were to be applied to the individual elemental x-ray map of the specified element: (i) Mg x-ray map = Red (gamma setting: 4, grey scale offset: -4). (ii) Si x-ray map = Green (gamma setting: 4, grey scale offset: -4). (iii) Zn x-ray map = Blue (gamma setting: 3, grey scale offset: -0). (i) To identify Mg2Si particles on the surface, a professional grade photo editing software tool, such as COREL Paint Shop Pro, was to be used to create a composite image of the red, green and blue coloured elemental x-ray maps. Mg2Si particles would appear as a yellow/orange coloured particles in the composite image. (j) The surface area fraction of all identified Mg2Si was to be measured using standard image analysis software and techniques. The surface area of the Mg2Si was to be reported as a % of the total surface area imaged. 127 Stage 3 being the coating thickness measurement involved the following steps. 128 As to the sample preparation steps: (a) Each 10mmx30mm length of samples A and B was to be mounted in a cold mount resin (such as Epofix) to allow preparation and viewing of the cross-section of the 30mm edge of each length. A 30mm length would be chosen by example as being appropriate for a 40mm diameter mount, where three to four lengths could be put into each mount. (b) The strip was to be polished to a 1-3μm diamond finish using standard metallographic grinding and polishing techniques, specifically avoiding edge rounding or staining/corrosion of the Mg2Si or the metal coating. An alcohol based diamond polishing lubricant such as Struers "DP-Lubricant Yellow" and absolute ethanol for cleaning would be used for the final stages of polishing to assist with the prevention of corrosion and staining. 129 As to the image capture methodology: (a) The metal coating thickness of one side of the strip would be measured at intervals of 0.5mm along each 30mm (a total of 60 measurements per 30mm cross-section) polished metallographic cross-section using an optical microscope at a magnification of 1000x, and the results recorded. (b) The metal coating thickness measurement would be repeated on the reverse side of each cross-section. (c) Cross-section images of the coating at 1000x magnification would be captured and saved for each side of each cross-section. (d) The microscope images would be calibrated using a certified calibration slide. 130 As to calculating average metal coating thickness, for each cross-section image, the average metal coating thickness (AMCT) would be calculated as follows: (a) One would threshold each image to highlight the area from the steel/alloy layer interface to the external metal coating surface. (b) One would measure the highlighted area in square microns. (c) One would measure the width of the image in microns. (d) One would calculate the AMCT by dividing the highlighted area by the width of the image. 131 As to the metal coating thickness variation measurement: (a) A 5mm width of cross-section (10 consecutive images long) would be randomly selected (see Figure 2 below). (b) The maximum AMCT measurement from the 10 consecutive image measurements, denoted as AMCTmax, would be identified and recorded. The minimum AMCT measurement from the 10 consecutive image measurements, denoted as AMCTmin, would be identified and recorded. (c) The average 5mm width metal coating thickness (A5MCT) would be calculated using the following formula: (d) Thickness variation would be calculated according to the following formula: Thickness Variation = (AMCTmax - AMCTmin) / A5MCT Figure 2: 5mm width cross-sections (10 consecutive images long) 132 As to the full width metal coating thickness measurement, one would separately calculate the top and reverse full width average metal coating thickness (FWAMCT) according to the following formula: Where S = Total number of consecutive 30mm mounted sections covering full width of strip. 133 Stage 4 being an assessment of the proportion of Mg2Si in the cross-sections involved the following steps: (a) The metallographic cross-sections previously prepared for optical thickness measurements were to be used for this stage. (b) The first and last cross-sections from each of samples A and B (four cross-sections in total) would be selected for analysis. (c) FE-EPMA would be used to create elemental maps. (d) Elemental maps for Mg, Si, Zn of the top and bottom metallic coated surfaces of the four selected cross-sections would be measured by FE-EPMA/WDS. (e) Two 150μm wide areas, five millimetres apart, on each selected metallic coated cross-section would be mapped (see Figure 3), at a resolution of 0.2µm per pixel, using a beam dwell time of 50 milliseconds. Each cross-section map would include the full thickness of the coating. Figure 3: Image of one selected 30mm cross-sections showing the two 150μm wide mapped areas (f) The maps would be generated using electron beam settings of 5kV for the accelerating voltage and a beam current setting of 50 nanoAmps (i.e., the same parameters used in Stage 2, step (d) that I have set out earlier). (g) The elemental maps for Mg, Si, Zn would be measured by WDS and captured as separate grey scale images. (h) The characteristic x-rays and spectrometer crystals to be used for each element were: Mg: Kα on TAPH crystal, Zn: Lα on TAPH crystal and Si: Kα on TAP crystal. (i) A professional grade photo editing software tool, such as COREL Paint Shop Pro, would be used to convert each grey scale elemental map to a colour and each map would be saved as a separate file. (j) The following colours and settings would be applied to the individual elemental x-ray map of the specified element: (i) Mg x-ray map = Red (gamma setting: 4, grey scale offset: -4). (ii) Si x-ray map = Green (gamma setting: 4, grey scale offset: -4). (iii) Zn x-ray map = Blue (gamma setting: 3, grey scale offset: -0). (k) To identify Mg2Si particles on the surface and in the cross-section, a professional grade photo editing software tool, such as COREL Paint Shop Pro, would be used to create a composite image of the red, green and blue coloured elemental x-ray maps. Mg2Si particles would appear as a yellow/orange coloured particles in the composite image. (l) The cross-sectional area of all identified Mg2Si particles within each 150μm wide mapped area would be measured using standard image analysis techniques available in proprietary image analysis software tools, such as Olympus' analySIS Pro. (m) The cross-sectional area of all identified Mg2Si particles within each 150μm wide mapped area that were in contact with the external surface of the metal coating would be isolated and measured as depicted in Figure 4 below. (n) To calculate the proportion of Mg2Si particles in the surface in respect of each mapped area, the cross-sectional area of the Mg2Si particles determined to be in the surface would be divided by the cross-sectional area of all Mg2Si particles. Figure 4: 150μm wide mapped area identifying the Mg2Si particles in the surface and not in the surface (o) To calculate the proportion of Mg2Si particles in the top 5% of the AMCT (258 Patent, claim 2): (i) one would, using the steel substrate/alloy layer interface as the reference line, measure the cross-sectional area of Mg2Si that resided above 95% of the AMCT (see Figure 5 below); (ii) one would calculate the proportion of Mg2Si in the 5% thickness surface region by dividing the cross-sectional area of Mg2Si residing above 95% of the AMCT by the total cross-sectional area of Mg2Si in the mapped area. Figure 5: 150μm wide mapped area identifying Mg2Si particles residing above 95% of the AMCT (p) All measurements and calculations were to be recorded. 134 At the conclusion of the experiments and measurements, the remainder of the March 2016 samples together with the discs and strips used for the measurements were to be securely stored in the same plastic sleeve packaging the March 2016 samples were supplied to BlueScope in. The remainder of the March 2016 samples together with the discs and strips were to be accessible to Dongkuk on request.

BLUESCOPE'S APPLICATION OF THE PROTOCOL 135 The experiments necessary to apply the protocol were conducted by Dr Stewart Ford, metal coating and characterisation specialist, Ms Louise Hodges, metallographer and coating analyst, and Mr Leslie Moore, metallurgist of BlueScope. 136 The experiments produced the following images: (a) Cross-sectional images (side view): A1 - A8, and B1 - B8 (16 cross-sections in total). (b) Surface images (top view): A Top, A Rev, B Top and B Rev (4 half discs in total). 137 The experiments produced measurements of: (a) coating thickness measurements (cross-section), which were relevant to all claims; (b) the proportion of Mg2Si in the surface of the coating (cross-section), which was relevant to all asserted claims of the 257 Patent except claim 15; (c) the amount of Mg2Si at the surface of the coating (surface), which was relevant to claim 15 of the 257 Patent; (d) the proportion of Mg2Si in a surface region of the coating that had a thickness that was less than 30% of the total thickness of the coating (cross section), which was relevant to claim 1 of the 258 Patent and dependent claims, although I note that BlueScope does not now press its allegation of infringement concerning claim 1; and (e) the proportion of Mg2Si in a surface region of the coating that had a thickness that was at least 5% of the total thickness of the coating (cross-section), which was relevant to claim 2 of the 258 Patent.

Calculation of the AMCT 138 The AMCT calculated for each optical image is a measurement of the area of the coating from the interface of the steel substrate and alloy layer to the external metal coating surface (in μm2) divided by the frame width of the image (in μm). 139 BlueScope measured eight 25mm x 7.5 mm cross sections from each of sample A and sample B. The protocol specified that the samples should be 30 mm x 10 mm. The reasons for diverging from the protocol were explained in the evidence of Dr Ford and Ms Hodges. In summary, the height of the material available was not 10 mm across the full strip, and as the mounts were 40 mm long, 30 mm sections would have been too long. These samples were sheared, creating sixteen cross sections (A1 - A8 and B1 - B8). Each cross section was placed into separate contamination free bags for cross sectional analysis. 140 The sixteen cross sections were divided into groups of four (A1 to A4, A5 to A8, B1 to B4 and B5 to B8). Each cross section was attached to a mounting clip and placed into a container and mounted in Epofix, a cold mounting resin. After the resin had cured, the cross sections were polished to a 3 μm diamond finish (or 1 μm, where required). 141 Using an optical microscope, BlueScope took 125μm wide images of the cross section of the coating, across the entire 25mm length, on both the top and reverse side of each cross section. Each cross sectional image for all but one sample was spaced at intervals of 0.5mm (four x 125μm) from centre to centre. One sample was measured at intervals of 0.52 mm, but was an error. On ten occasions of the 1579 images taken, the image location was varied by up to 50 μm due to unevenness in the intermetallic layer. 142 BlueScope took a total of 47 to 50 optical images per cross section. 143 To define the interface of the steel substrate and alloy layer and to ensure that the interface was horizontal, BlueScope rotated the images of the cross sections, when required, using the line of best fit approach to ensure that the area of alloy layer above and below the line was equal. 144 BlueScope adjusted the frame area of the cross section images to 122μm wide to exclude alterations to the border of the cross section image which result from the rotation and set the colour thresholds on the image analysis software program to include the metal coating and interface but to exclude the mounting resin. 145 The area of the coating was then measured in terms of square microns (μm2), and the AMCT was calculated by dividing the coating area (in μm2) by the frame width (in μm). 146 BlueScope repeated this process and measured the AMCT for each of the optical images, on both the top and reverse side for each of the sixteen cross sections. BlueScope took a total of 1579 AMCT measurements across each of the top and reverse side of the sixteen cross sections. 147 BlueScope recorded the raw data for each of the AMCT measurements in an Excel spreadsheet titled "171130 Thick Measurement Data and Summary". 148 One of BlueScope's experts Dr Tomáš Prošek, a materials engineer, considered that the interface of the steel substrate and alloy layer should be set at a different point and undertook his own measurements of the AMCT using the optical images taken by BlueScope. 149 But although Dr Prošek's measurements of the AMCT varied slightly from BlueScope's by between 3 and 5%, the difference was so small that it did not affect his calculations. Dr Prošek used BlueScope's measurements to undertake his analysis. 150 Dr Prošek applied Chauvenet's criterion, being a statistical theory that identifies data points from a set of data that are outliers, and concluded that the AMCT results for samples B7 Top 25, B7 Top 26, B6 Top 20, B7 Top 27, B7 Top 24, A5 Rev 34 and B5 Rev 29 were outliers. I will return to the question and treatment of outliers later. 151 Dr Prošek determined that the coating thickness of the GLX product was 17 μm or greater but less than 27 μm.

Calculation of the AMCTmin & AMCTmax 152 The evidence establishes that the distance between ten contiguous images from centre to centre was at least 5mm in diameter. 153 Given that Ms Hodges took approximately 47 to 50 images across the 25 mm diameter length of each cross-section sample, the results for 10 contiguous images had to be identified from the total of 47 to 50 images for that cross section to generate a 5mm diameter section. 154 On this basis, Dr Prošek first satisfied himself that the thickness calculations across a random sample of 10 contiguous images, which represented a 5mm diameter section, was representative of the thickness calculation across any random 5mm diameter section. 155 To identify a "representative" 5mm diameter section for testing, BlueScope prepopulated a formula into its thickness measurement spreadsheet. The formula randomly selected the results from ten consecutive AMCT measurements and identified the AMCTmax and the AMCTmin for that sample of ten AMCT measurements. 156 BlueScope also prepopulated the following formulas, which I have set out earlier, in its thickness measurement spreadsheet: (a) The formula to calculate A5MCT: (b) the thickness variation across a 5mm diameter section being: (c) the formula for FWAMCT being: 157 I would note that for the last formula "S" is equal to 8, the total number of cross sections across the full width of each of samples A and B. 158 BlueScope's thickness measurement spreadsheet was used to randomly select ten contiguous AMCT results representing a 5 mm diameter section, and to calculate the A5MCT, and the thickness variation for the 5 mm diameter section based on the above formulas. 159 The thickness measurement spreadsheet recorded an A5MCT measurement and thickness variation measurement for each side (top and reverse) for each of the sixteen cross sections (A1 to A8 and B1 to B8). 160 The thickness measurement spreadsheet randomly generated different A5MCT and thickness variations for a 5mm diameter section contained within the same cross section sample by randomly selecting a new starting point measurement for each A5MCT measurement.

Calculation of the FWAMCT 161 The thickness measurement spreadsheet used the eight A5MCT results from each side (top and reverse) for each of the eight cross sections (A1 to A8 or B1 to B8) to calculate the FWAMCT of the sample for both the top and reverse side of sample A and sample B. 162 Dr Prošek confirmed that the thickness variation calculation across a random sample of ten AMCT measurements was representative of the thickness variation across any ten AMCT measurements. 163 To undertake his analysis, Dr Prošek selected a random sample of ten images for each of the sixteen cross sections (both for the top and reverse side). 164 Dr Prošek concluded that for sample A, the thickness variation across a 5mm diameter section varied between 8% and 26%, and for sample B varied between 6% and 51%. 165 I would note that Dr Prošek did not identify thickness variations of between 39.8% and 112.3% for sample B7 as identified by Professor Michael Cortie, a physical metallurgist and one of Dongkuk's experts, because the ten images Dr Prošek randomly chose from the total of 50 images for cross-section sample B7 Top did not include samples B7-Top-25 and B7-Top-26. 166 Using statistical principles, Dr Prošek concluded that for cross section B6 Top, the thickness variation calculation of 51% was as a result of an outlying thickness measurement B6 Top 20, being the twentieth AMCT measurement for cross section B6 on the top side, which was an exception and should be excluded. 167 Dr Prošek concluded that the thickness variations (excluding B-Top-6), were significantly lower than 40% and 30%.

(b) Calculating the amount of Mg2Si particles at the surface of the sample 168 Before getting into the detail, let me note some aspects of metallurgy that were not controversial. 169 The metallurgy of Al-Zn-Si-Mg coatings is dependent upon the formation of the coating microstructure and the intermetallic phases formed within the coating microstructure. 170 The initial phase to form when the coated steel strip is solidifying is the intermetallic layer or "alloy layer". The intermetallic layer forms at the interface between the steel substrate and the metallic coating, and it begins to form as the steel strip is submerged into the coating bath. In general, the intermetallic layer consists of Fe-Al-Si intermetallic compounds. 171 The metallic coating primarily consists of the Al-dendrites, which is the second phase that begins to form. Zn and Mg are soluble in Al, so the Al-dendrites will contain significant concentrations of Zn and a small amount of Mg. On the other hand, Si is relatively insoluble in Al, so the Al-dendrites will only contain insignificant amounts of dissolved Si. 172 Most of the Zn, Mg and Si is rejected from the growing Al dendrites, resulting in a liquid enriched in Zn, Mg and Si. As the coating is cooled, most of the Si and some of the remaining Mg, being from the Zn, Mg and Si rich liquid, forms Mg2Si, meaning that the remaining liquid is enriched with Zn and Mg. Some Si precipitates as metallic Si. The remaining Zn and Mg enriched liquid forms MgZn2. 173 The final liquid of the metallic coating to solidify results in a complex eutectic mixture of Al, Zn and Mg rich phases, including MgZn2, Mg2Si, Zn-MgZn2-Al, Zn-5%Al and metallic Si. 174 The formation of the coating microstructure is complex, and requires the right chemistry, solidification path and thermal processing. 175 To determine the location and amount of the Mg2Si phase in the coating, it is necessary to devise a process to detect and identify the Mg2Si phase of interest in analytical samples of the coating. This process is generally known as thresholding. 176 As I have referred to earlier, BlueScope measured and sheared one 50 mm disc from each of sample A and sample B. Each 50 mm disc was sheared in half creating four half discs (A Top, A Rev, B Top and B Rev) and placed into separate, labelled, contamination free bags for EPMA surface analysis. The samples were cleaned with ethanol and compressed air, and carbon coated to a thickness of approximately 15 nm to prevent the samples from becoming electrically charged by the electron beam. 177 An FE-EPMA was used to ascertain the microstructure of the GLX product. Separate areas for each half disc were mapped. The areas were mapped at a resolution of 1 μm per pixel. An accelerating voltage of 5 kV and a beam current setting of 50 nanoAmps was used. The areas mapped were randomly selected. 178 The FE-EPMA scanned each 1 μm pixel within each of the mapped areas of each half disc to identify the elements present in the pixel. Using wavelength dispersive spectrometry and characteristic x-rays and spectrometer crystals, spectrometers within the FE-EPMA captured the X-rays of the elements of interest (Mg, Si and Zn) that were diffracted, creating elemental maps for each of Mg, Si and Zn for each mapped area. Each elemental map was a spreadsheet containing a number of X-ray counts for each pixel mapped. 179 Mr Moore recorded the minimum and maximum X-ray count values for each of the Mg, Si and Zn maps from each mapped area of sample A, and entered these values into an in-house purpose built program to convert each elemental map from its original 4 byte integer csv file format into a 1 byte grey scale, bitmap image. 180 Although there is no real top limit to the value of the X-ray counts, the average maximum and minimum values ranged from: (a) 12 to 578 for Mg; (b) 6 to 690 for Si; and (c) 22 to 464 for Zn.

(c) Creation of the RGB (red, green, blue) map 181 Mr Moore produced a colour map that identified the location of the Mg2Si particles (as yellow phases), so that he could find the corresponding area of the Si map corresponding to the Mg2Si phase. 182 A professional grade photo editing software tool, COREL Paint Shop Pro, was used to convert each of the X-ray grey scale elemental maps to a colour map by applying specified colours and gamma and offset value settings to the individual elemental X-ray map of each element by attributing red to the Mg X-ray map, green to the Si X-ray map and blue to the Zn X-ray map. The gamma setting and grey scale offset values were applied to improve the visual delineation of the boundary of the Mg2Si phase, to compensate for any effect of ZAF factors, which I will explain in a moment. Mr Moore explained that the gamma correction enhanced the separation between the metallic Si and Mg2Si, the MgZn2 and the Mg2Si, and the Zn rich interdendritic regions and the Al-dendrites, to discriminate between the Mg2Si from the surrounding matrix. 183 Each of the gamma corrected Si, Mg and Zn elemental maps were combined to create a composite red, green, blue (RGB) image, where the Mg was depicted as red, Si as green and Zn as blue, where Mg and Si together was depicted as yellow, and where Mg and Zn was depicted together as purple. 184 Once an RGB map was generated, Mg2Si regions were identified by their yellow colouration. 185 According to Mr Moore, the above process took into account any ZAF factors because the gamma correction minimised any variations in the Mg:Si ratio, enhanced the yellow pixels and created a clear boundary of the Mg2Si evidence in the RGB map. 186 As Mr Moore explained it, ZAF factors refers to the factors that affect electron microscopy, namely atomic number (Z), absorption (A) and secondary fluorescence (F). Let me set out his description which I did not understand to be controversial. 187 "Z" refers to the atomic number (Z) factor, being of course the number of protons in the nucleus of an atom, which also characterises where an element appears on the periodic table. The Z factor describes how the atomic number of the element contributes to the resulting X-ray yield result. As the electron beam hits the sample, the electrons spread within the sample and may generate X-rays that are detected by the EPMA. When the electrons collide with the atoms in the sample, the electrons begin to lose energy. The rate of energy loss depends on the elements present in the sample. Part of the electrons will backscatter and will not penetrate the sample, which is also dependent on the elements in the sample. These two factors are mainly dependent on the atomic number of the sample. The X-ray yield for widely varying atomic numbers, i.e. elements that are far apart from each other on the periodic table, can result in quite a large difference in X-ray yield and therefore any effect of Z factors must be corrected. 188 "A" refers to the absorption of the X-rays as they exit the sample, being the portion of the generated X-rays that are absorbed by the atoms in the specimen, and not released from the sample, and therefore not detected by the detector. The amount of absorption of the X-ray is also dependent on the atomic number because different elements absorb X-rays from other elements to different extents. If the energy of the X-ray is above the absorption edge energy of the atoms in the material it is exiting through, it may be absorbed. By absorption edge energy is meant the energy at which there is a sharp rise in the absorption coefficient of X-rays by an element. 189 "F" refers to the secondary fluorescence of X-rays by other X-rays, where the other X-rays can be from the background spectrum or from other elements. By this is meant that there may be instances where the electron collides with element Z and generates an X-ray. But such an X-ray, rather than being detected by the detector, may be absorbed by element Y, and that absorption may then give rise to the generation of an X-ray from element Y which is then detected. In such circumstances the detector will detect an X-ray from element Y, rather than from element Z. 190 In the Al-Zn-Si-Mg coating system, Mg, Al and Si are consecutive elements in the periodic table. Therefore the effect of atomic number on the Z factor is relatively minor. But the effect of absorption of the X-rays (the A factor) and the secondary fluorescence of X-rays (the F factor) is significant because of the Al present. This is because Al Kα X-rays have a higher energy line than the Mg Kα absorption edge, meaning Al X-rays can be absorbed by Mg, resulting in the fluorescence of Mg X-rays rather than Al X-rays. This erroneously increases the yield of the Mg X-rays generated and subsequently detected by the FE-EPMA. The effect of Al X-rays on the Mg yield is greater than Si X-rays, because Al is closer to the Mg Kα absorption edge. 191 In the course of Mr Moore's work with Al-Zn-Si-Mg coatings, he undertook extensive modelling to investigate geometry and spatial resolution issues in microanalysis. As part of his work, he investigated the quantitative microanalysis of Mg2Si entities within an Al matrix at different accelerating voltages of 5kV, 7kV, 10kV and 15kV. 192 The modelling showed that a presence of 5% Al in the interaction volume would result in an error of more than 1 % in the wt% of Si and Mg measured in the final analysis of Mg2Si. For this reason, according to Mr Moore, the contribution of Al X-rays from the dendrites immediately underneath the Mg2Si had to be kept to a minimum. This required fine spot sizes and low kV to minimise the depth of penetration. The effect of Al on the Mg:Si ratio for various kV and phase sizes depicted as ɸ (in μm) is shown in Figure 6 below. Figure 6: Effect of Al Ka presence (expressed as a K ratio) on the Mg:Si ratio for various kV and phase sizes (ɸ) 193 In Mr Moore's view, the thresholding procedure he established was sound and comprehensively took into account any ZAF factor effect of the Al in the substrate to mitigate these effects. This was because of the use of the gamma transformation of the RGB images, and the use of a statistically based thresholding technique.

(d) Silicon map 194 Using the RGB map as a visual guide to identify the location of the Mg2Si phases, BlueScope reviewed the data from five of the Si elemental maps, being the raw data produced from the EPMA machine without any gamma correction applied, and identified the Si X-ray counts that were associated with Mg2Si regions. Mr Moore chose the Si X-ray counts from pixels that were wholly contained within the Mg2Si particle, avoiding the boundaries, to avoid including a Si X-ray count that related to a different phase. 195 BlueScope extracted, culled and assembled the Si X-ray counts from the five separate Mg2Si regions, and calculated the Si X-ray count lower threshold associated with the Mg2Si data array, by subtracting three standard deviations from the average Si X-ray count. According to Mr Moore, each of the Si X-ray counts was a Poisson variant, such that he could be confident that the average of a normal distribution was also normal. 196 Mr Moore obtained a Si X-ray count value that he was confident was the minimum value to represent a Mg2Si X-ray count, and that any value below the threshold value would not represent an Mg2Si phase. The threshold X-ray count value for Si that was determined by Mr Moore was 101, where the minimum Si X-ray count was 6. 197 Because the image analysis software Mr Moore used worked within a range of zero to 255, the threshold value was converted to a 0-255 grey scale value. The grey scale threshold value for Si was 35. 198 Using COREL Paint Shop Pro, BlueScope applied this grey scale value to each Si X-ray map to generate a binary image in which only the Si pixels, that is, those pixels containing an X-ray count higher than the Si X-ray count threshold of 35, were highlighted white; the balance of the image representing other elements was black. 199 This process removed (by blacking out) those pixels in the binary map that contained an X-ray count value below the threshold value. The resulting binary Si map only identified pixels as white pixels containing both metallic Si and Mg2Si. 200 To exclude the metallic Si, and to create a map that contained only Mg2Si, Mr Moore combined the Si map together with the Mg map. But in some specific cases this method did not exclude all of the metallic Si.

(e) Magnesium map 201 BlueScope then manually thresholded the Mg elemental maps by visually comparing the Mg2Si phases present in the Mg grey scale map with the Mg2Si present in the RGB maps. 202 Because of the innate statistical variations for Mg and this manual thresholding procedure, the Mg threshold image could be smaller than the Si threshold image. According to BlueScope the binary image of Mg and Si could under-represent the number of pixels associated with Mg2Si. 203 To overcome this problem and avoid improperly culling Mg2Si pixels, BlueScope dilated the Mg thresholded map by a factor of two pixels. But in some cases the dilation operating inflated the size of the Mg2Si. 204 BlueScope then used the COREL Paint Shop Program to create a binary map of Mg2Si, and used the measure function on the image analysis program ImageJ to measure the surface area percentage of Mg2Si as a percentage of the total image area. 205 The average area fraction for sample A was 0.15%, with the individual measurements varying between 0.07% and 0.23%. 206 The average area fraction for sample B was 0.23%, with the individual measurements varying between 0.08% and 0.38%. 207 Now because this calculation compared the proportion of Mg2Si particles to all phases of the coating rather than comparing the Mg2Si particles to Mg2Si particles in the entire microstructure, the area fraction did not equal the weight fraction or weight percent. 208 But Dr Prošek explained that the average area fraction corresponded to the average volume fraction, and the average weight fraction (or wt.%) could be calculated as follows: 209 Galvalume was used as a proxy because the presence of Mg would have an insignificant effect on the overall density of the Al-Zn-Si-Mg product. Since the density of Mg2Si is 1.99 g/cm3 and the density of galvalume is 3.8 g/cm3, the weight fraction of Mg2Si particles could be estimated from the area fraction by multiplying the area fraction with a coefficient of 0.52 (1.99/3.8). 210 So adjusting, for sample A the relevant proportion was 0.08%, and for sample B the relevant proportion was 0.12%.

(f) Calculating the proportion of Mg2Si particles in the surface of the coating (cross section) 211 BlueScope cleaned the first and last cross sectional samples of samples A and B (A1, A8, B1 and B8) with ethanol and compressed air, and carbon coated the cross sections to a thickness of approximately 25 nm. BlueScope used FE-EPMA to map two 150 μm x 32 μm (or 40 μm depending on the sample) areas for each of the four cross sections, at a resolution of 0.2 μm, resulting in elemental maps for Mg, Si and Zn for each mapped area. 212 BlueScope thresholded each of the Si and Mg maps (and then dilated the Mg map by two pixels) and created a binary map of Mg2Si for each mapped area. 213 BlueScope identified all of the Mg2Si particles in the surface of each mapped area, and using ImageJ, measured the cross sectional area of all the Mg2Si particles in the surface, divided by the cross sectional area of all Mg2Si particles present in the total image. 214 As Dr Prošek explained, since this proportion compared the distribution of Mg2Si particles only, the area fraction was equal to the weight fraction or weight percent. For sample A, this proportion was 0.42% and for sample B, 0.40%.

(g) Calculating the proportion of Mg2Si particles in the top 5% of the thickness of the coating of the samples 215 Let me deal with the top 5% aspect. Mr Moore explained the matter in the following terms. 216 Stage 4 of the protocol identified that the steel substrate / alloy layer interface would be used as the reference line to delineate between the top 5% of the AMCT and the bottom 95% of the AMCT. But during the conduct of the experiments it became apparent to Mr Moore that the unevenness and angle of the interface affected the estimation of the top 5% of the AMCT. Mr Moore chose to use a line of best fit approach to locate this boundary, which allowed for angle and irregularities in the interface. 217 Using the Back Scattered Electron (BSE) images, Mr Moore recorded the number of pixels in the X- and Y-axis in an Excel spreadsheet entitled "Mg2Si In top 5% Area Calculation". This spreadsheet automatically calculated the number of pixels in the whole image by multiplying the number of pixels in the X-axis by the number of pixels in the Y-axis. 218 From Mr Moore's experience he understood that the average grey level on a 0-255 scale for a thresholded black and white image would be a rough estimate of the area of the image coloured in white, when divided by the upper limit of the grey scale, being 255. Given that each of the BSE images were black and white images, where the coating was coloured in white, he understood that he could use the average grey level to calculate the area of the coating as a percent of the whole image. 219 Using the histogram palette on COREL Paint Shop Pro, he obtained the average grayscale for each of the BSE images and calculated the area of the coating as a percentage of the area mapped by dividing the average grey scale by 255 and multiplying by 100. He recorded the coating area percent for each mapped area into his spreadsheet, which automatically calculated: (a) the number of the pixels in the coating, by multiplying the number of pixels in the whole image by the coating area percent divided by 100; and (b) the 95% average thickness coating Y-axis coordinate (95% Avg Coating Thick Y-Axis) by dividing the number of pixels in the coating by the number of pixels in the X-axis (which in all cases was 750 pixels), multiplied by 95%. 220 Using the line of best fit model, he established the left (bottom) and right (top) Y-axis coordinates of the steel substrate / alloy layer interface (respectively, the Y-Axis Left and Y-Axis Right). According to Mr Moore, the line of best fit took into account any slope in the image and that the black pixels above the line balanced out with the white pixels below the line shown in Figure 7 below. Figure 7: Image showing the line of best fit 221 He then subtracted each of the Y-Axis Left and Y-Axis Right from the 95% Avg Coating Thick Y-Axis to predict the left and right y-axis coordinates in the top 5% of the AMCT, shown by the blue line in the Figure 8 below. Figure 8: Image showing the line of best fit and the line estimating the top 5% 222 Using COREL Paint Shop Pro, he drew a 1 pixel wide black line on the image, which is shown by the blue line in the Figure above. He then deleted all of the pixels below the blue line, leaving just the top 5% of the AMCT in white, which is shown in Figure 9 below. Using ImageJ, he measured the area of the estimated top 5% of the AMCT, calculated as a percentage of the whole coating. Figure 9: Image showing the top 5% of AMCT 223 If the area of the top 5% of the AMCT was greater than 5%, he moved the estimated top 5% line (as shown by the blue line in Figure 8) up, one pixel. Using ImageJ, he remeasured the area. He repeated this process until he had established the left (bottom) and right (top) y-axis pixel that corresponded to one pixel below the top 5%, and one pixel above the top 5%, of the AMCT, respectively, with the "true" 5% boundary falling somewhere between these two pixels. These steps deviated from the protocol which stated that the area above the 95% of the AMCT would be measured. Instead he measured the area falling one pixel above the 95% AMCT and one pixel below the 95% of the AMCT. He recorded the area of the boundary >5% and =1050mm wide due to strip flutter through the jets and upleg cooling. Air flotation is an emerging technology in galvanising lines, which can reduce/eliminate strip stability issues at the pot. It is proposed that installation of the BSL floater pad air jets, in combination with the Hatch or Spooner Air Stabilizer above the jets will allow speed increases on wide product on MCL1. The potential flow on process benefits from installation of this air flotation technology include better coating mass distribution, and improved cooling prior to the after pot turn roll. Deflector rolls may be disengaged for light gauge strip production, eliminating deflector roll chatter defects and reducing delays and maintenance costs. 937 But none of these considerations related to controlling sub 5mm coating thickness variations. 938 It would seem that BlueScope was the first company in the world to transfer the concept of using air flotation stabiliser technology from galvanising/galvanneal production to galvalume production. But the hypothetical skilled addressee reading the specification at the filing date is non-inventive and not taken to think laterally. And nor does he possess knowledge of emerging technologies in galvanising and galvannealing. 939 Further, as Dongkuk submitted, it appears likely that the origin for BlueScope's idea was idiosyncratic. It first trialled, although unsuccessfully, its air flotation stabiliser pad technology in galvalume production when MCL 4 was repurposed from galvanising/galvannealing to galvalume. This is referred to in the attachment to the said minutes: Floater pad air knife technology was developed by BSR, and has successfully been implemented on MCL6 for galvanised steel and galvanneal. The floater pads have been trialled on MCL4 for an extended period for Zincalume® Steel production. … While the BSR floater pad will supress vibrations at the air knife from the pot rolls, large string type vibrations between the sink roll and after pot turn roll will have a high moment at the air knife. Further stabilisation above the air knife is proposed to eliminate these vibrations. Spooner Industries supply a stabiliser that can be installed directly above the air knife. The illustrated 1100mm long stabiliser could be installed in the existing air knife frame, which is roughly the same dimension from the top of the hanger frame to the air jet. Spooner Industries claim 20 air flotation installations on galvanising lines. BSR-Hatch have also trialled an air flotation system on MCL3. This is still in the prototype stage and limited trials have been conducted to date, but the results have been promising. 940 A further attachment to the minutes included a list of references from Spooner Industries Ltd. But it did not refer to the use of an air flotation stabiliser in galvalume production. 941 Further, a "Briefing Note - Air Floater Stabiliser Pad Trial" dated 12 June 2008 by Mr Garry Peterson, Mr Darren Thompson and Mr Lopez also supports the fact that the idea of implementing an air flotation stabiliser was not routine. This document reported on a May 2008 trial of an air flotation stabiliser by Hatch Engineering on a galvalume line. Now this document noted that "it appears this technology has the potential to provide [a number of] business benefits" including its viability of manufacturing the new EDGE product. But there were a number of problems, namely: (a) "the test floater pad arrangement was not optimal in terms of relative position to the air knives, strip to floater pad distance or maximum operating pressure hence gains could potentially be higher under the same operating as the trial"; (b) "[o]ne other factor to note is that the condition of the front stabiliser roll & [its] bushes at the start of the trial generated a high degree of vibration which approached the acceptable limits of operation prior to a rig change"; and (c) "[n]oise levels in the pot area were noticeably increased by the operation of the floater pad in combination with the standard air jet". 942 It was stated: The coating mass variation was reduced substantially (from Standard Deviation of 8.1g/m2 to 2.7g/m2 - refer to Graph#4) and improved surface finishes apparent during the trial. The best results were obtained with the front stabiliser roll disengaged and the floater pad applied with a plenum pressure of approx. 3kPa (maximum possible with test arrangement). It should also be noted that the test floater pad arrangement was not optimal in terms of relative position to the air knives, strip to floater pad distance or maximum operating pressure hence gains could potentially be higher under the same operating as the trial. One other factor to note is that the condition of the front stabiliser roll & [its] bushes at the start of the trial generated a high degree of vibration which approached the acceptable limits of operation prior to a rig change. Whilst this may affect the relative change in results, it represented a near extreme test for the stabilising effect of the floater pads. Noise levels in the pot area were noticeably increased by the operation of the floater pad in combination with the standard air jets. However, a more permanent installation would incorporate an edge baffle system into the stabilisers to reduce the turbulence near the strip edges. As a result of the above & the fact that no new defects were introduced by the floater pad during the albeit limited trial, it appears this technology has the potential to provide the following business benefits: • Improved strip stability and consequently coating uniformity in longitudinal & transverse directions. This may also enable a tightening of the target coating masses to save on excess coating metal. • Enabler to run significantly closer jet to strip distances providing a fundamental shift in current operating windows for jet strip[p]ing with implications on: • Low Coating classes (AZ70 > 130mpm) to be produced at higher speeds without defects such as "Pock Marks" etc. • Zincalume to be produced at over 200 mpm. • Viability of manufacturing new EDGE product. • Potential to run without a front stabiliser roll on light gauge lines (to be confirmed) with associated reductions in maintenance & downtime costs. • Reduced stabiliser roll "shadow" marks hence improved quality & appearance of bare metallic coated products. 943 Mr Lopez agreed that at this stage further work needed to be done. This document also referred to the fact that one of BlueScope's motivations for using an air flotation stabiliser was to produce lower coating classes at greater line speeds, which had little to do with controlling sub 5mm coating thickness variations. Mr Lopez confirmed that controlling sub 5mm coating thickness variation was not one of the motivations for using air flotation stabilisers on galvalume. In the circumstances, a person skilled in the art would not understand that the "special operational measures" used to control the sub 5mm coating thickness variation referred to in the specification included the use of such a stabiliser. 944 Mr Lopez also confirmed that after the May 2008 trial, considerably more work was done by BlueScope and Hatch Engineering in experimenting, developing and trialling the air flotation stabiliser with galvalume. Those trials included at least trials in 2009, 2010, and in 2012. 945 It is clear that at least as at November/December 2009 that BlueScope was having considerable difficulties with using an air flotation stabiliser with the EDGE (MAZ) coating. These difficulties were reported in an email chain ending in an email from Mr Lopez to Mr Thompson copied to Mr Renshaw and others reporting on outcomes of the first EDGE stripping DOE dated 20 November 2009. In an email of 19 November 2009 from Mr Renshaw to Mr Lopez, Mr Thompson and others, Mr Renshaw stated: The first in a series of 8 designed jet stripping experiments (DOEs) was conducted last night on MCL 4. These experiments were designed to provide answers to some fundamental questions about the jet stripping behaviour of the Edge (MAZ) coating. The key questions are: • What is the benefit of very low jet-strip distances (25 g/m2 ii) Painted Corrosion Resistance First, one side was subjected to chromic acid-silica based treatment to 20 mg/m2 based on metallic Cr, as chemical treatment. Next, a test sample with dimensions of 70x150 mm was subjected to 20 μm melamine-based black painting, and baked at 140℃. for 20 minutes. A crosscut was then formed and the sample was provided for a salt spray test. The outer appearance after 60 days was visually observed. Evaluation Scale ⦾: No red rust ○: No red rust outside of crosscut ∆: Red rust ratio ≦5% X: Red rust ratio >5% iii) Outdoor Exposure Test The sample was painted after the chemical treatment described in ii) above. The painting was carried out with two types of paints, a polyethylene wax-containing acrylic-based resin (clear: 5 μm) and an epoxy-based resin (20 μm). After shearing to dimensions of 50x200 mm, the sample was subjected to an outdoor exposure test. The red rust ratio and surface coloration condition were observed from the edge after a period of 3 months. Evaluation Scale ⦾: Red rust ratio from edge 80% (2) Weldability After the chemical treatment described in ii) above, spot welding was conducted under the welding conditions shown below, and the number of continuous spots until the nugget diameter reduced to below 4√t (t: sheet thickness) was evaluated. Welding Conditions Welding current: 10 kA, Pressure force: 220 kg, welding time: 12 cycles, Electrode diameter: 6 mm, Electrode shape: dome-shape, Tip: 6ɸ-40R Evaluation Scale ⦾: Number of continuous spots >700 ∆: Number of continuous spots 400-700 ○: Number of continuous spots 25 g/m2 ii) Painted Corrosion Resistance First, one side was subjected to chromic acid-silica based treatment to 20 mg/m2 based on metallic Cr, as chemical treatment. Next, a test sample with dimensions of 70x150 mm was subjected to 20 μm melamine-based black painting, and baked at 140℃. for 20 minutes. A crosscut was then formed and the sample was provided for a salt spray test. The outer appearance after 60 days was visually observed. Evaluation Scale ⦾: No red rust ○: No red rust outside of crosscut ∆: Red rust ratio ≦5% X: Red rust ratio >5% 1100 Kurosaki discloses the use of a number of additional elements, the last of which is Sr, which are said to improve corrosion resistance when added in small amounts. Sr is only one of many listed elements. There is no direction or statement which would direct the user to use Sr in preference to any of the additional elements. 1101 Kurosaki reports on the performance of these additional elements in Table 2, as part of a composition of 55 wt.% Al, 5 wt.% Mg and 5 wt.% Si (and 35 wt.% Zn). 1102 It would seem that the list of elements in Table 2 and at the bottom of column 6 is there because they are elements which can be added to achieve improved corrosion resistance. Table 2 does not allow the reader to identify the contribution made by Sr to corrosion resistance in relation to any of the other elements, since Sr is not reported as being better than any of the other elements. Professor Marder concluded from Kurosaki that Sr does not affect Mg2Si in the coating or change corrosion performance. He said that the only contribution it might make is to passivation. Dr Prošek said that if there was an effect on passivation, it would be seen in the corrosion results.

Mottle/ visual defects 1103 Kurosaki is not concerned with providing a surface which is free of visual defects such as mottle. The only reference to the appearance of the product is in the context of identifying that a coating with a bulky Mg2Si phase will experience a loss of spangle. Further, there is no suggestion, direction or recommendation in Kurosaki that the addition of Sr would alter the distribution of the Mg2Si phase or resolve any visual defect.

Coating thickness variations 1104 Kurosaki does not include any discussion relating to thickness uniformity or the importance of controlling short range coating thickness variations. Further, it is not possible to predict the coating thickness variation for any composition including low Mg2Si compositions from Kurosaki.

Distribution of Mg2Si 1105 Dongkuk has done no experiments which would allow me to ascertain the microstructure of the coating used or described in Kurosaki. Instead, it relies on inferences sought to be drawn from Figures 3 and 4. But it appears to have been ultimately accepted that Figures 3 and 4 of Kurosaki, which are of a perpendicular view rather than a horizontal one, are not an accurate guide to the amount of Mg2Si at particular locations. Further, nothing about the microstructure of any of the examples is disclosed. 1106 Further, there are no measurements or calibration that would enable the surface region of the coating depicted in Figures 3 and 4 to be determined. There is no comment on the proportion of Mg2Si that would be in the surface or the surface region. 1107 Further, Kurosaki does not disclose that there are detrimental effects of having Mg2Si particles in the surface of the coating. Kurosaki does not suggest controlling the distribution of the Mg2Si particles. It focuses on controlling their size and shape. It suggests that a coating which has bulky Mg2Si particles forming up to 30% of the coating layer will provide excellent corrosion resistance. More particularly, Kurosaki does not disclose a coating having a distribution of Mg2Si particles in the coating microstructure where there is only a small proportion of Mg2Si particles or substantially no Mg2Si particles in the surface of the coating. 1108 Now I accept that Dr Prošek gave evidence that he believed that following the disclosure of Kurosaki would result in an even distribution of Mg2Si throughout the coating. But it is apparent from his evidence elsewhere that he did not consider this to be an inevitable result because Dr Prošek accepted that other processing parameters could affect the microstructure. And in any event, the effect of Dr Prošek's evidence was that a skilled addressee would aim to achieve an even distribution. But even if that goal were achieved that would not amount to anticipation. 1109 Further, Mr Dutton's evidence was that it was not possible to know without trying the samples in Kurosaki what microstructure would be produced. 1110 Further, Mr Rommal's evidence was that it he did not know what the specific microstructure of any of the examples in Kurosaki would be. 1111 In my view Kurosaki does not anticipate claims 1, 3 to 9 or 11 to 15 of the 257 Patent.

(c) Nisshin - the 257 Patent 1112 Nisshin was published on 28 November 2000 and stands in the name of Nisshin Steel Co Ltd. Nisshin claimed the following: [Claim 1] An Mg-containing hot-dip Zn-Al alloy plated steel sheet having high corrosion resistance and good surface appearance, the Mg-containing hot-dip Zn-Al alloy plated steel sheet comprising: a plating layer formed on a surface of a steel sheet, wherein the plating layer contains, by mass%, Al: 25 to 70%, Mg: 1.5 to 5.0%, Sr: 0.01 to 1.0%, and contains Si in a range satisfying the following Equation (1) and the balance being Zn and unavoidable impurities: Al (mass%)x0.005□Si (mass%)□10 · · ·(1) [sic]. [Claim 2] An Mg-containing hot-dip Zn-Al alloy plated steel sheet having high corrosion resistance and good surface appearance, the Mg-containing hot-dip Zn-Al alloy plated steel sheet comprising: a plating layer formed on a surface of a steel sheet, wherein the plating layer contains, by mass%, Al: 25 to 70%, Mg: more than 5.0 to 6.0%, Sr: 0.07 to 1.0%, and contains Si in a range satisfying the following Equation (1) and the balance being Zn and unavoidable impurities: Al (mass%)x0.005□Si (mass%)□10 · · ·(1) [sic]. [Claim 3] The Mg-containing hot-dip Zn-Al alloy plated steel sheet of claim 1 or 2, wherein Si is contained in a range satisfying the following Equation (1)': Al (mass%)x0.03□Si (mass%)□10 · · ·(1)' [sic]. [Claim 4] The Mg-containing hot-dip Zn-Al alloy plated steel sheet of any one of claims 1 to 3, wherein a plating amount per one surface of the steel sheet is 40 to 120 (g/m2). 1113 The discussion of the background was as follows: [0002] A hot-dip Al plated steel sheet has an advantage in that corrosion resistance of a plated surface is excellent as compared to a hot-dip Zn plated steel sheet. However, since Al does not have a sacrificial protection effect on Fe, unlike Zn, the Al plated steel sheet is inferior to the Zn plated steel sheet in that red rust may easily occur in an exposed portion of base steel such as a damaged portion of a plated surface, a cut cross section of the steel sheet, or the like. [0003] As a steel sheet in which the advantage of the Al steel sheet, that is, excellent corrosion resistance of the plated surface, and the advantage of the Zn plated steel sheet, that is, the sacrificial protection effect are balanced and introduced, a hot-dip Zn-Al alloy plated steel sheet containing 25 to 70 mass% of Al is disclosed in Japanese Patent Laid-Open Publication No. S46-7161, and as the hot-dip Zn-Al alloy plated steel sheet described above, for example, a Zn-Al (55 mass%) - Si (1.6 mass%) alloy plated steel sheet has been put to practical use. 1114 So, the context concerned the question of corrosion resistance rather than mottling. Nevertheless the body of the specification discussed the question of a wrinkle like defect. 1115 A brief summary of the invention stated the following: [0005] However, generally, a plated steel sheet in which Mg is added to hot-dip Zn-Al alloy plating (hereinafter, referred to as Mg-containing hot-dip Zn-Al alloy plated steel sheet) has not yet been widely used in spite of an excellent effect of improving characteristics as described above. Particularly, a hot-dip Zn-Al alloy plated steel sheet containing Mg in a large amount (at least several % order) in a plating layer has not yet been commercialized as an industrial product in spite of significantly excellent corrosion resistance. [0006] The main reason for the delay in industrial distribution of the Mg-containing hot-dip Zn-Al alloy plated steel sheet is that a technology of manufacturing a Mg-containing hot-dip Zn-Al alloy plated steel sheet having good surface appearance using a general hot-dip plating line is not established. [0007] FIG. 1 is three photographs illustrating surface appearance of a hot-dip Zn-Al alloy plated steel sheet having a plate width of 60 mm, manufactured using a continuous hot-dip plating simulator (test line). Here, in all of the photographs, left and right end portions correspond to edges of the steel sheet, and a plate passing direction in each of the photographs is a direction from the bottom to the top. [0008] A photograph in the upper part of FIG. 1 illustrates an example of a hot-dip Zn-Al alloy plated steel sheet that does not contain Mg. The Mg-free hot-dip Zn-Al alloy plated steel sheet has almost smooth and good surface appearance. Further, white parts seen as a spangle shape (some of them are seen as a stem shape) in the photograph in the upper part, which reflect crystal grains in the plating layer, are not defects. A photograph in the middle part of FIG. 1 illustrates an example of a hot-dip Zn-Al alloy plated steel sheet containing about 1% of Mg. A white stem extended from both edge portions to a lower portion of an oblique line is observed. This stem is a portion having a wrinkle-like uneven surface. In the case of adding Mg to a hot-dip Zn-Al alloy plating bath, the above-mentioned wrinkle-like unevenness (hereinafter, referred to as a wrinkle-like defect, or wrinkle-like unevenness defect) is generally formed in a plated surface, which deteriorates surface appearance of a product, thereby deteriorating a value of the product. A photograph in the lower part of FIG. 1 illustrates an example of a hot-dip Zn-Al alloy plated steel sheet containing about 6% of Mg. When a large amount of Mg is contained as described above, the wrinkle-like defect is formed in the vicinity of a central portion of the plate in a width direction as well as edge portions thereof, such that surface appearance is significantly deteriorated. [0009] An object of the present invention is to provide an Mg-containing hot-dip Zn-Al alloy plated steel sheet having high corrosion resistance and good surface appearance in which a wrinkle-like defect is suppressed, capable of being manufactured using a general hot-dip plating line in which a surface of a plating bath is under air atmosphere. [0010] The wrinkle-like defect is significantly prevented by allowing an Mg-containing hot-dip Zn-Al alloy plating layer to contain a trace amount of Sr. That is, according to claim 1 of the present invention, there is provided an Mg-containing hot-dip Zn-Al alloy plated steel sheet having high corrosion resistance and good surface appearance, including: a plating layer formed on a surface of a steel sheet, wherein the plating layer contains, by mass%, Al: 25 to 70%, Mg: 1.5 to 5.0%, Sr: 0.01 to 1.0%, and contains Si in a range satisfying the following Equation (1) and the balance being Zn and unavoidable impurities: Al (mass%) x0.005□Si (mass%)□10 · · ·(1) [sic]. [0011] Here, a chemical composition of a hot-dip plating layer may be specified by dissolving the plating layer in a solution such as an HCl solution, or the like, and analyzing the solution using inductively coupled plasma (ICP) atomic emission spectrometry. Since in manufacturing of a hot-dip plated steel sheet, a surface of the steel sheet generally reacts with a plating metal to thereby be slightly dissolved, elements (iron, and the like) derived from the steel sheet are slightly contained in the plating layer. In the present invention, these elements are also considered as the unavoidable impurities. An Si content in the plating layer may be specified by Equation (1). More specifically, for example, in the case in which an Al content in the plating layer is 25 mass%, the Si content may be specified in a range of 0.125 to 10 mass%, and in the case in which the Al content in the plating layer is 70 mass%, the Si content may be specified in a range of 0.35 to 10 mass%. 1116 In a detailed description of the illustrated embodiments the following was said: [0016] Mg serves to cover a surface of a plating layer and an exposed portion of base steel with a corrosion product when a hot-dip Zn-Al alloy plated steel sheet is under a corrosion environment, thereby further improving original corrosion resistance of the hot-dip Zn-Al alloy plated steel sheet. That is, Mg in the plating layer serves to form intermetallic compounds with Zn and Si, that is, MgZn2 and Mg2Si, and these intermetallic compounds serve as Mg sources promoting formation of stable protective corrosion products in the corrosion environment. Therefore, the surface of the plating layer is rapidly covered with uniform corrosion products, and these corrosion products are stably present and exhibit their protective film functions, such that corrosion resistance of a plated surface is improved. Further, since the exposed portion such as a cut cross section, or the like, of the base steel is also covered with these corrosion products, early disappearance of the plating layer caused by a galvanic effect between Zn in the plating layer and Fe in a plating back plate may also be suppressed. That is, Mg serves to maintain the sacrificial protection effect while improving corrosion resistance of the plated surface. [0017] When the Mg content in a Zn-Al alloy plating layer is less than 1.5 mass%, this corrosion resistance improvement effect is not sufficiently obtained. Further, when the Mg content is more than 6 mass%, it is difficult to sufficiently suppress a wrinkle-like unevenness defect in the surface of the plating layer even in the case of adding Sr to be described below. Therefore, the present invention relates to an Mg-containing hot-dip Zn-Al alloy plated steel sheet in which the Mg content in the plating layer is in the range of 1.5 to 6.0 mass%. [0018] At the time of manufacturing the hot-dip Zn-Al alloy plated steel sheet containing a large amount of Mg as described above, generally, the wrinkle-like unevenness defect may occur as described above, thereby significantly deteriorating surface appearance of the hot-dip Zn-Al alloy plated steel sheet. The reason is that growth of an oxide film on a surface of a molten metal is significantly promoted by adding Mg to the plating bath, and thus the oxide film inhibits a uniform flow of a plating metal in a molten state. [0019] The present inventors found that when a suitable amount of Sr is contained in a plating layer, a wrinkle-like defect problem as described above may be solved. The reason may be that in a non-solidified surface of the plating layer picked out from the plating bath, Sr is preferentially oxidized than Mg, and thus oxidation of Mg is suppressed. [0020] It is preferable that a Sr content in the plating layer is 0.01 to 1.0 mass% when the Mg content is 1.5 to 5.0 mass%. When the Sr content is less than 0.01 mass%, an effect of suppressing the wrinkle-like defect is hardly exhibited. However, when the Sr content is more than 1.0 mass%, spot-like unevenness caused by an Al-Si-Sr based intermetallic compound may occur, thereby deteriorating surface appearance of the plating layer . In the case in which the Mg content is high (more than 5.0 to 6.0 mass%), it is preferable that a lower limit of the Sr content is increased to 0.07 to 1.0 mass%. When the Si content is less than 0.07 mass%, the wrinkle-like defect may not be sufficiently suppressed. … [0024] The Mg-containing hot-dip Zn-Al alloy plated steel sheet according to the present invention may be manufactured using a general continuous hot-dip plating line. The present inventors confirmed through a separate experiment that in the Mg- containing hot-dip Zn-Al alloy plating, a composition of the plating bath is almost reflected as it is in a composition of the plating layer in the plated steel sheet. Therefore, at the time of manufacturing the Mg-containing hot-dip Zn-Al alloy plated steel sheet according to the present invention, there is a need only to adjust the Al content, the Si content, the Mg content, and the Sr content in the plating bath so as to coincide with the composition of the plating layer to be desired. 1117 Importantly, Table 1 reported on the following results: 1118 I will discuss Table 1 and some of the entries in more detail later. But I should make some observations at this point in terms of what Table 1 displays. The description for Example 1 gives the following explanation: [0025] Hot-dip Zn-Al alloy plated steel sheets in which Mg and Sr contents were variously changed were manufactured using a continuous hot-dip plating simulator (continuous hot-dip plating test line). Plating conditions were as follows. • Base steel sheet: cold-rolled Al killed steel (thickness: 0.8 mm, width: 60 mm) • Maximum Temperature Reached by Sheet in Reduction Furnace: 700°C , Dew point: -35°C • Sheet passing rate: 50 m/min • Composition (mass%) of plating bath: Al:55%, Si:1.6%, Mg:0-7%, Sr:0-1.5%, and the balance being Zn and avoidable impurities • Temperature of plating bath: 605°C • Immersion time : 3 seconds • Cooling after plating: air cooling (cooling rate: 20°C/s) [0026] Surface appearance of the manufactured hot-dip plated steel sheets was observed by the naked eyes, and an occurrence degree of a wrinkle-like defect was ranked into four levels (⦾, ⚪, △, and x) As an evaluation standard, the surface appearance was ranked as follows using samples illustrated in the photographs in FIG. 1. • ⦾: The hot-dip plated steel sheet had good surface appearance equivalent to or more excellent than that of a sample at the top in FIG. 1. • ⚪: The hot-dip plated steel sheet had surface appearance worse than that of the sample at the top but equivalent to or more excellent than that of a sample in the middle in FIG. 1. • △: The hot-dip plated steel sheet had surface appearance worse than that of the sample in the middle but more excellent than that of a sample at the bottom in FIG. 1. • x: The hot-dip plated steel sheet had surface appearance equivalent to or worse than that of the sample at the bottom in FIG. 1. [0027] A case in which the wrinkle-like defect occurred was also evaluated as "⚪". However, even in this case, surface appearance was significantly improved as compared to a material according to the related art, and it is considered that a product value of the hot-dip plated steel sheet was sufficient depending on the uses. Therefore, in the present invention, when the surface appearance was evaluated as "⦾" or "⚪", it was determined that surface appearance was good. However, since a case in which spot-like unevenness attributed to an Al-Si-Sr based intermetallic compound was formed means that even though occurrence of the wrinkle-like defect was sufficiently suppressed, a novel defect that did not occur in the material according to the related art occurred, this case was evaluated as unevenness exists. [0028] Further, after each of the plated steel sheets was exposed in a coastal industrial belt in Sakai City, Osaka Prefecture for 3 months in a state in which a 2t bending processing part and a cross-cut part (a portion at which an X-shaped scratch was formed on a surface of the plating layer) were formed in each of the plated steel sheets, and at the same time, the base steel was exposed in a cut cross section thereof, a degree of inconspicuousness of red rust was evaluated. A commercial Zn-Al (55 mass%)-Si (1.6 mass%) alloy plated steel sheet that did not contain Mg was used as a standard sample, and the degree of inconspicuousness of red rust was observed by the naked eyes and was ranked into four levels (⦾, ⚪, △, and x) as follows. • ⦾: Red rust was hardly seen. • ⚪: Red rust was more inconspicuous than that of the standard sample. • △: Red rust was inconspicuous similarly to that of the standard sample. • x: Red rust was more conspicuous than that of the standard sample. [0029] Further, a composite cyclic corrosion test (CCT) was performed on each of the plated steel sheets. CCT conditions were determined according to Japan Automobile Standards Organization (JASO) M609-91 standardized by the Society of Automotive Engineers of Japan, and one cycle was composed of salt water spray (5% normal saline) at 35°C for 2 hours → drying at 60°C and relative humidity 30% for 4 hours → wetting at 50°C and relative humidity 95% for 2 hours. A cross section and an entire inner surface of the test sample were sealed with an insulating tape and used in the test. After completing CCT 200 cycles, corrosion products were removed by a 10% ammonium chloride aqueous solution (solution temperature: 60°C), and a corrosion mass loss (g/m2) was calculated from a mass difference before and after the test, thereby evaluating corrosion resistance of the plated surface. These results were illustrated in Table 1. 1119 I will return to this later, but samples 27 to 30 are shown as the optimum samples in terms of good surface appearance and more modest corrosion mass loss. I should also note that sample 1 is galvalume. It would also seem from these results that surface appearance deteriorates as Mg increases. So it might be said that Nisshin teaches away from the 257 Patent and the 258 Patent. 1120 Now Dongkuk points out that Nisshin concerns a hot-dip coating method for coating a steel strip, with the method having Al-Zn-Si-Mg in the coating in the ranges claimed in claim 9 of the 257 Patent; see especially Example 1 Table 1 samples 20 to 22 and 27 to 29. Mg2Si is formed in the coating alloy. Dongkuk says that the distribution of Mg2Si would fall within claims 1, 3 and 15 of the 257 Patent in accordance with each or all of the methods set out in the 257 Patent. Dongkuk says this for the following reasons. 1121 First, the thickness of the Nisshin product would be controlled by ordinary good practice. 1122 Second, the cooling rate in Nisshin is only 20°C/sec. 1123 Third, the samples include Sr in the range 0.05-0.3% by wt (500-3000ppm). 1124 Now Nisshin is directed towards an Mg-containing hot-dip Zn-Al alloy plated steel sheet having high corrosion resistance and good surface appearance. 1125 Nisshin discloses that a plated steel sheet in which Mg has been added to hot dip zinc and alloy had not yet been widely used in spite of its excellent effect in improving characteristics, which relates to corrosion resistance. Nisshin explains that the product has not been commercialised because it has not been possible to produce a sheet having a good surface appearance. 1126 Nisshin is particularly directed towards suppressing a "wrinkle-like" defect associated with the addition of Mg to Al-Zn alloy coatings. 1127 Nisshin discloses an Mg-containing hot-dip Zn-Al alloy plated steel sheet where the plating layer contains, by mass %: (a) 25 to 70 wt.% Al; (b) 1.5% to 5 wt.% Mg; (c) 0.01 to 1.0 wt.% Sr; (d) Si according to the following formula: Al (mass%) x 0.005 ≤ Si (mass%) ≤ 10%, and the balance being Zn and unavoidable impurities. 1128 Figure 1 of Nisshin contains three images illustrating the surface appearance of three Zn-Al alloy plated steel sheets. In my view the images are of such poor quality that they provide little assistance with understanding the nature of the defect. 1129 The "wrinkle-like" defect is described as a defect which arises when Mg oxidises with O2. This forms Mg-oxides that grow as an oxide film on the surface of the molten bath. As the metal strip is drawn out of the molten bath, the Mg-oxides inhibit the uniform flow of the molten metal onto the strip. 1130 The "wrinkle-like" defect is associated with oxide drag out which causes the Mg-oxide film to adhere to the coated surface of the strip as it exits the molten bath, or to form on the molten metal after the strip exits the bath. The following evidence was given: MR CAINE: Thank you. Then if we come across to paragraph 18 on page 13, they refer again to the wrinkle-like unevenness defect, and then at about 5 line 18 they say the reason is that the growth of an oxide film on the surface of the molten metal is significantly promoted by adding magnesium to the plating bath and thus the oxide film inhibits a uniform flow of a plating metal in a molten state. So that that's telling us that there's an oxide film that forms on the surface of the molten bath; that's right, isn't it? MR ROMMAL: It's telling us that there is an oxide film that forms on the molten coating metal that could be on the surface of the bath or it could be on the surface of the molten metal after the strip exits the bath. MR CAINE: As the metal strip is drawn out of the bath, I wanted to put to you the magnesium oxides inhibit the uniform flow of the molten metal on to the strip. MR ROMMAL: It says inhibits the uniform flow of a plating metal. It doesn't say flow of the metal from the bath to the strip. It could be flow of the metal once it's on the surface of the strip in terms of its motion in response to gravity or other airflow in the vicinity above the bath. MR CAINE: So the description of the wrinkle defect is one that's not clear to you? MR ROMMAL: It's not clear to me whether the wrinkle defect is magnesium oxide patches pulled out on the surface of the coating or whether it's non-uniform coating thickness on a small scale caused by magnesium oxide getting in the way of the molten metal flowing freely somewhere either on the bath or once it's applied to the - to the coated strip. 1131 This causes the surface appearance to deteriorate, resulting in a "wrinkle-like" surface defect. 1132 Nisshin indicates that additions of Sr to the molten bath may solve the "wrinkle-like" defect. Nisshin suggests that because Sr is more favourably oxidised than Mg, the oxidation of Mg is suppressed. This reduces the amount of Mg-oxide film available for drag out onto the coated surface, suppressing the "wrinkle-like" defect. 1133 The specification explains that the wrinkle-like defect is significantly prevented by allowing the coating to contain Sr, in an amount from 0.1 to 1%. 1134 Nisshin refers to an upper limit for Sr of 1 wt.% (10,000 ppm). This is to ensure that another defect, described as "a spot-like unevenness" caused by Al-Si-Sr, does not occur. The lower limit for Sr is dependent on the amount of Mg. A lower limit for Sr of 0.01 wt.% is described where the Mg content is 1.5 to 5 wt.%. A lower limit for Sr of 0.07 wt.% is described where the Mg content is 5 to 6 wt.%. 1135 Now it would seem that the "wrinkle-like" defect described in Nisshin is a surface defect. But as Mr Dutton observed, the defect is not the surface defect mottle to which the 257 Patent is addressed. The "wrinkle-like" defect is a defect resulting from the formation of Mg-oxides on the molten bath which inhibit the uniform flow of the molten metal onto the strip. In contrast, mottle is a defect resulting from the formation of a non-uniform distribution of Mg2Si particles in the surface of the coating microstructure. 1136 Nisshin provides three examples of the Mg-Al-Zn alloy coating of the invention. The examples are assessed by reference to the naked eye. Table 1, which contains the results of 49 different samples, relates to compositions with 55 wt.% Al, 1.6 wt.% Si, Mg from 0 to 7wt. %, and Sr from 0 to 1.5 wt.%. Table 2 relates to compositions with 25 wt.% Al. And Table 3 relates to compositions with 70 wt.% Al. 1137 Let me say something about Table 1. 1138 Sample 1 of Table 1 is the composition equivalent to galvalume, which is used as a comparator. The results for samples 1, 2 and 3 showed that as Mg was increased (from 0 wt.% to 1.0 wt.%), corrosion resistance improved, that is, mass loss reduced. However, at Mg levels of 5 wt.% and above, surface appearance issues started to arise. Samples 27 to 30 appear to have been the "best". They have the optimal balance of surface appearance, minimal red rust and corrosion resistance. Those samples contain Al in the amount of 55 wt.%, Si in the amount of 1.6 wt.%, Mg in the amount of 4 wt.%, Sr in amounts up to 1 wt.% (that is, up to 10 000ppm), and Zn in the amount of up to 39.4 wt.%. No coating mass for the samples is given. 1139 In my view it seems reasonably clear that insofar as the results in Table 1 direct the reader to any particular samples, they are samples 27 to 30. This is fatal to Dongkuk's assertion of anticipation. 1140 Now Dongkuk relies on samples 20 to 22 as anticipatory, but I disagree as I will explain shortly. 1141 Let me say something about the other Tables. Mr Rommal's earlier evidence was that "the results set out in Table 1 in terms of surface appearance and red rust are superior to those set out in Table 2 and Table 3", but Dr Prošek did not agree. In my view, the results set out in Tables 1, 2 and 3, in relation to surface appearance and red rust are consistent and do not vary despite the change in Al and Si composition. I accept that Mr Rommal later corrected his early statement stating that his "intention was to say that the results set out in Table 1 are nearly identical in terms of surface appearance and red rust compared to Table 2 and Table 3, but the corrosion mass loss results in Table 1 are superior to those set out in Tables 2 and 3". 1142 Let me now deal with a number of points. 1143 First, Nisshin does not focus on developing a specific coating microstructure. Rather, Nisshin focuses on controlling a production issue that causes oxide to build up, giving rise to the "wrinkle-like" defect. The "wrinkle-like" defect is not the result of microstructural issues. 1144 Second, Nisshin refers only briefly to Mg2Si. The context of this brief discussion is that Mg2Si is said to promote the formation of a stable product with improved corrosion resistance. Mr Rommal explained that Nisshin is talking about products of oxidation of magnesium spreading across the surface of the coating. If those corrosion products are not easily redissolved, because they are stable, then they can serve as a barrier to further corrosion. Mg2Si is a source of the magnesium which forms the barrier. At least some must be present at the surface of the coating to provide corrosion protection. Further, both Dr Prošek and Mr Dutton understood from the brief reference to Mg2Si that it was desirable to have Mg2Si at the surface of the coating in order to improve corrosion resistance. 1145 Third, Nisshin does not identify where the Mg2Si particles are located in the coating microstructure. 1146 Fourth, Nisshin is not concerned with providing a surface which is free of visual defects such as mottle. The only reference to the appearance of the product is to a wrinkle-like defect, which is not mottle. 1147 Fifth, Nisshin makes no reference to controlling coating thickness variations. In terms of coating thickness, Nisshin claims a coating mass in the range of 40 to 120g/m2, but otherwise does not refer to coating mass. The coating mass used in the tabulated results is not known. 1148 Sixth, Nisshin does not suggest that controlling the cooling rate will impact upon the distribution of Mg2Si particles. Further, it does not describe that the cooling rate will affect the appearance of the coated strip. Similarly, Nisshin does not describe the effect of cooling rate on corrosion resistance and the resulting microstructure. The same bath temperature (605°C) is used throughout. The same cooling rate of 20°C/sec is used in all the samples, despite different coating bath compositions. 1149 Seventh, although Nisshin describes that Sr assists with the appearance of the coating, Nisshin does not describe what effect the addition of Sr has on the diffusion of the Mg2Si particles. Dr Prošek concludes that Sr has no effect on the microstructure. This is because if it did, there would be a change in the corrosion resistance results. But as was pointed out in the evidence, the samples in Nisshin do not show that there was any improvement to the corrosion resistance properties across a range of 0 to 1.5 wt.% Sr (15,000 parts per million) when the amount of Al, Si and Mg remained constant. 1150 Further, samples 27 to 30, which performed best against the criteria tested, namely surface appearance evaluation, red rust test and corrosion mass loss test, had less than 40 wt.% Zn and were therefore outside the scope of claim 9 of the 257 Patent. 1151 Now as Dongkuk pointed out, samples 20 to 22 had alloy ranges which corresponded with the alloy ranges set out in claim 9 of the 257 Patent. But although Dongkuk relies upon samples 20 to 22 as anticipatory, Dr Prošek would not have made those samples. Moreover, he did not accept that if he made samples 20, 21 and 22 and exercised ordinary good manufacturing practice, he would have arrived at the claimed Mg2Si distribution. 1152 Further, although Dr Prošek accepted that the addition of Sr would affect Mg2Si distribution, he considered that the structure disclosed in Nisshin clearly had large amounts of Mg2Si at the surface. This was necessary for the protection mechanism that was claimed, being a stable corrosion product. That protection mechanism would not work without Mg-rich phases exposed at the surface, including not only Mg2Si, but also MgZn2. 1153 Further, Mr Dutton also understood that there would be Mg2Si close to the surface, if not in the surface. 1154 Further, Mr Rommal considered that there would have been some Mg2Si or MgZn2 at the surface, but that the amount would depend on the dissolution rate in the corrosive environment and how much corrosion product was required to provide protection. He explained: Nisshin is specifically calling out the two intermetallic compounds Mg2Si and MgZn2 as potential sources of the magnesium. In order for the stable magnesium corrosion product to cover the surface of the plating layer providing additional corrosion protection, you would have to have some source of magnesium present at the surface or close enough to the surface that when the corrosion of the coating begins - the very beginning of corrosion you've down to it and now you've got some magnesium available at the new surface. … So it has to be either at the surface or close to the surface in some quantity to be able to make that corrosion product. 1155 Now although Professor Marder observed that Nisshin does not say how much Mg2Si is present at the surface, and he speculated that MgZn2 could be the source of Mg, I agree with BlueScope that that observation does not assist Dongkuk. Nisshin does not clearly disclose a coating which contains only a small proportion of Mg2Si in or near the surface of the coating. 1156 In summary, Nisshin does not anticipate claims 1, 3 to 9 and 11 to 15 of the 257 Patent.

(d) The Nolan article & the Nolan thesis - the 257 Patent 1157 Dongkuk has submitted the following. 1158 Dongkuk relies on the Nolan article and the Nolan thesis taken together on the basis that they are related documents that a person skilled in the relevant art in Australia would treat as a single source of information pursuant to s 7(1)(b) of the Act. 1159 Nolan was variously funded, employed and contracted by BlueScope (and its predecessor, BHP Steel). The Nolan article and the Nolan thesis were published in 1993 and both are by the same author. The Nolan thesis is referred to in the Nolan article. In particular, the Nolan article states "[c]oatings were produced using a controlled hot-dip galvanizing cycle" (at p 86), referencing the Nolan thesis. Dongkuk says that it is axiomatic that in producing a coating in accordance with the teachings in the Nolan article, the skilled addressee would refer to the Nolan thesis. I agree. 1160 In the Nolan article, under the sub-heading "Experimental", Nolan explains that he obtained a Zn-Al-Si alloy by melting commercial grade zincalume. Mg was added to the liquid zincalume alloy mixture at different percentages to examine the effect of the addition of Mg to zincalume. At p 86 it is said that coatings were produced using a controlled hot-dip galvanising cycle and reference is then made to the Nolan thesis. In the Nolan thesis it is said that: The base material for the present work was commercially produced and chromate passivated ZINCALUME in sheet form, with base thickness of 1.0 mm and coating mass of 150 g/m2. The base steel was an aluminium-killed, fully recrystallised low alloy steel. The sheets were marked and sheared into coupons 110 mm by 350 mm with the long direction in the rolling direction of the steel coil. 1161 Nolan explains his use of the so called "double-dipping" method to coat the steel with the alloy. He says that: In this method, a sample of ZINCALUME was cleaned and preheated before being immersed in a liquid ZINCALUME alloy. While immersed in the liquid, the coating on the sample dissolved and when the sample was removed from the liquid, a new ZINCALUME coating was substituted in place of the original coating. This new coating, with the composition of the liquid alloy [including Mg], was subjected to the similar principles of coating thickness control and accelerated cooling as the original coating. Trials using the Double-Dipping method showed that it was possible to consistently produce high quality coatings… 1162 It is not expressed in either the Nolan thesis or the Nolan article that the variation in thickness of the coating was no more than 40% in any given 5mm diameter section and that that "limitation" on thickness variation caused the distribution of Mg2Si particles to be such that there was only a small proportion or substantially no Mg2Si particles in the surface of the coating. But Dongkuk says, based on the teaching of the 257 Patent, that distribution of Mg2Si would be the outcome of Nolan's method because his cooling rate was only 12.3°C per second. Further, Dongkuk says that it is clear that Nolan was in any case also concerned with ensuring coating thickness uniformity. Further, Dongkuk says that as a matter of fact, the majority of Mg2Si was in the bottom two thirds of the coating. 1163 As to the first of these matters, Dongkuk points to various passages in the Nolan article. 1164 As to the second matter, Dongkuk says that the photomicrographs presented by Nolan in the Nolan thesis demonstrate the Mg2Si phase growing from the intermetallic alloy layer, and not from nor reaching the surface of the coating. 1165 Dongkuk says that I should reject BlueScope's submission that neither the Nolan article nor the Nolan thesis are novelty defeating disclosures because the Nolan article does not relate to coated steel strip made by a hot dip coating process because it is a laboratory sample. It says that the samples created were created on a simulated production environment which involved hot dip coating using zincalume samples obtained from BlueScope's predecessor. It says that this method is valid and the results can be accepted within the bounds of commercial sheet production. Further, the point of Nolan is to report the addition of Mg to zincalume for the purpose of coating steel sheet products. 1166 Further, Dongkuk says that BlueScope's rejection of the Nolan article on the basis that the amount of zinc was not 40 to 60% is not a legitimate rejection. It says that the results relied upon by BlueScope reflect the coating composition dissolved with additional Fe from the intermetallic layer and so it is the alloy's composition that is relevant in the Nolan thesis and not the coating composition figures. 1167 Let me analyse each piece of prior art in turn.

The Nolan article 1168 The Nolan article reports on the effects of adding magnesium on the coating microstructure. It reports on the addition of Mg to zincalume in the amounts of 0.1, 0.5, 1 and 2.5 wt.%. 1169 The Nolan article does not describe the process by which the product was made. 1170 At this point, let me set out some extracts. 1171 At pp 86 to 87 the following is said: EXPERIMENTAL Liquid Zn-55%Al-1.6%Si alloy was prepared by melting ingots of commercial grade ZINCALUME alloy in a graphite crucible. The ZINCALUME was obtained from the No.l Galvanizing Line at the Springhill Works of BHP Steel - Sheet and Coil Products Division at Port Kembla. Magnesium was added to the liquid ZINCALUME using pure metal in ingot form with 99% purity. Nominal concentrations of the magnesium-additions were 0.1, 0.5, 1.0 and 2.5 weight percent. Alloy samples were taken in the form of air-cooled ingots (10mm x 10mm x 80mm) and water quenched beads (for chemical analysis). Coatings were produced using a controlled hot-dip galvanizing cycle (12). Alloy compositions were determined by dissolving samples in hydrochloric acid and analysing the solutions, using Atomic Absorption Spectroscopy for zinc, iron and magnesium, photometric analysis for silicon and the aluminium content was calculated by difference. Coating compositions (including alloy layers) were determined by dissolving coatings in a rhodine inhibited hydrochloric acid solution and analysing the solutions using Inductive Coupled Plasma Spectroscopy. Alloy samples and coating cross-sections were mounted in low curing temperature epoxy resin, thus avoiding any possible heat treatment associated with thermosetting mounts. The mounted specimens were ground on progressively finer abrasive paper and then polished using 4-8μm, 1-3μm and 0-1μm Buehler diamond paste on motorized polishing wheels. After each polishing stage the mounts were placed in ethanol in an ultrasonic unit before being washed in a stream of ethanol and blown dry with forced air. Difficulties were encountered during polishing due to the undesirable etching of the zinc-rich regions, and great care had to be taken to achieve a satisfactory surface finish with minimum polishing time. The polished specimens were then carbon coated in the unetched condition and examined using a JEOL JSM-840 Scanning Electron Microscope (SEM) in secondary electron imaging mode at 15kV. Images were recorded on Ilford HP5 film using an attached auto-exposure unit. The EDS spectra for compositional analysis of phases were taken using 25% dead time. The "volume of influence" of the incident electron beam, when generating x-rays for EDS analyses, was considered to be approximately 1μm3. RESULTS AND DISCUSSION Alloy and Coating Compositions Alloy and coating compositions are provided in Table 1. These show that the nominal addition concentrations were very closely approximated in the ZINCALUME alloys and coatings. The absence of results for the 0.5%Mg coating is due to experimental error is coating dissolution for analysis. The high iron concentrations in the coatings are expected as a result of the dissolution of the intermetallic alloy layer along with the coating overlay in the chemical analysis. The slightly lower addition concentrations in the coatings is a consequence of the high iron content and, if the compositions were to be normalized with the iron content set to approximately 0.4%, the addition concentrations would be closer to those of the alloys. 1172 I should note that end note (12) that is referred to on p 86 refers to the Nolan thesis. 1173 Then at pp 89 and 90, the following is set out: Effects of Magnesium Additions on Coating Microstructure With the addition of 0.1 %Mg, there were no obvious changes to the microstructure of the ZINCALUME control coating, shown in Fig.1. However, magnesium was detected in the most central zinc-rich region (shown at A in Fig.8) where the composition was found to be 94%Zn-3%Al-3%Mg. The corresponding phase region in the alloy microstructure (shown at A in Fig.4) had the composition 90%Zn-6%Al-4%Mg and was designated the V-phase. It is therefore proposed that the phase in the centre of the interdendritic regions in the coating is also the V-phase. With the addition of 0.5%Mg, there were two significant changes to the microstructure. The first of these was the Mg-Si phase growing from the intermetallic alloy layer, as shown at A in Fig.9(a). The composition of this phase was found to be 61%Mg-39%Si and is consistent with that of the phase, Mg2Si, which appeared at the magnesium concentration of 0.5% in the alloy microstructure. It should be noted that the occurrence of this phase was not common in the 0.5%Mg coatings, and the predominant silicon-bearing phase was the III-phase. The second of the changes was the presence of a homogeneous phase in the most central regions of the zinc-rich interdendritic regions, as shown at B in Fig.9(b). This phase was found to have the composition 82%Zn-16%Mg-2%Al. It is therefore proposed that this phase is MgZn2, which was observed at the same magnesium concentration in the alloy sample. Magnesium was also occasionally detected in small amounts in the II-phase regions (the fine zinc-rich interdendritic regions). The microstructure of the coatings containing 1.0%Mg was very similar to that of the coatings containing 0.5%Mg. Perhaps the only notable difference was the greater volume fraction of MgZn2, though no attempt was made to quantify this. It was also noted that there appeared to be clearer definition between the zinc-rich interdendritic regions and the aluminium-rich denrites, as shown in Fig.10. This confirmed the observations made on alloy samples, where the same effect was noted with a 1.0%Mg addition. Some magnesium was detected in the fine zinc-rich eutectic (the composition at A in Fig.10 was 80%Zn-15%Al-5%Mg). However, this result was not consistent, and at some II-phase regions no magnesium was detected. With 2.5%Mg, the most significant change related to an increase in the volume fraction of the Mg2Si phase. Figure 11 is an example of a typical ZINCALUME + 2.5%Mg coating structure, showing Mg2Si existing mostly in contact with the quaternary intermetallic alloy layer. Compositional analyses showed that all of these silicon-rich particles were Mg2Si. It is considered possible that these large and numerous panicles of Mg2Si might be responsible for an observed grain refinement in these coatings (12), as Marder has suggested that silicon particles at the alloy/overlay interface act as sites for dendrite nucleation. It is also possible to distinguish the coarse Zn-Mg eutectic, shown at A in Fig.11, which had the composition of 95%Zn-5%Mg. It is proposed that this is the Zn-MgZn2 eutectic referred to in the discussion of the alloy samples. It was noted that magnesium was not detected in the fine zinc-rich regions, the aluminium-rich dendrites, or the quaternary intermetallic alloy layer. 1174 Let me say something about Figure 9(a) of the Nolan article. 1175 The Nolan article discloses that when 0.5 wt.% Mg was added, the Mg2Si phase started to grow from the intermetallic layer, as shown in Figure 9(a). Region A of Figure 9(a) shows the Mg2Si phase, but the Nolan article does not describe in quantitative terms the proportion of Mg2Si in any part of the microstructure. 1176 Let me say something about Figure 11 of the Nolan article. 1177 The Nolan article discloses that when Mg2Si was added in the amount of 2.5 wt.%, the most significant change related to an increase in the volume fraction of Mg2Si, as shown in Figure 11. The Nolan article discloses that Mg2Si is mostly in contact with the quaternary intermetallic layer, but does not otherwise describe the location of the particles. 1178 Otherwise, the Nolan article does not expressly refer to the proportion of Mg2Si in any part of the coating, or provide any quantitative reference to the amount of Mg2Si referable to the surface region. Although the photomicrograph is unclear, Figure 9(a) shows that Mg2Si extends from the intermetallic layer and Figure 11 may show Mg2Si at the surface. 1179 Professor Marder's evidence was that the photomicrographs were of poor resolution, and might not be able to discern fine particles. Professor Marder accepted that whilst Mg2Si was apparent at the interface: We don't know how [Mg2Si] has manifested in the coating at the surface because we can't resolve that in the magnifications or the photomicrographs that we see here … we don't see the top of the tree, but we don't know if it isn't there. 1180 The Nolan article discloses that above 0.5 wt.%, Mg was present as Mg2Si particles and as the Mg content increased, the quantity and size of the Mg2Si particles changed. The Nolan article suggests that the Mg2Si particles formed preferentially at the interface between the coating overlay and the intermetallic layer at 0.5 wt.%, where Mg was at higher levels (2.5 wt.%), Mg2Si appears throughout the coating thickness. 1181 Let me say something about short range coating thickness variation. The Nolan article does not disclose short range coating thickness variations, or any means taken to control them. Moreover, good manufacturing practice cannot be used to supplement the disclosure. 1182 Let me say something about the distribution of Mg2Si. 1183 It is not possible to conclude from the Nolan article that there is a small proportion of Mg2Si particles or a distribution of Mg2Si which has no more than 10 wt.% in the surface region of the coating that has a thickness of less than 30%. Neither the description nor the images clearly identify which particles are Mg2Si. 1184 Let me say something about cooling rate. The cooling rate does not provide an answer to the absence of disclosure, because the evidence does not support the proposition that cooling rate alone will achieve the claimed microstructure. 1185 Further, the Nolan article did not produce a coating with 40-60 wt.% zinc as claimed in claim 9 of the 257 Patent and claim 1 of the 258 Patent. The double dipping process used by Dr Nolan differs from a commercial product in the thickness of the quaternary intermetallic layer and in the coating composition. 1186 Further, Table 1 of the Nolan article shows that the amount of Zn in the coating compositions varied from 38.5 to 39.6 wt.%. Moreover, Mr Rommal did not suggest that Nolan had 40 to 60 wt.% Zn in the coating. His evidence is that the coating could be normalised in order to make a comparison of the coating composition with the bath composition. 1187 In my view the Nolan article does not anticipate whether standing alone or when read with the Nolan thesis.

The Nolan thesis 1188 The Nolan thesis does not anticipate the relevant claims of the 257 Patent. 1189 The Nolan thesis describes the double dipping method, which used zincalume as a base material. The zincalume samples were cleaned and preheated, and then immersed back into the bath, which dissolves the coating, and as the zincalume sample is withdrawn from the bath a new substitute coating forms on the sample. 1190 The Nolan thesis describes the processing steps for each sample and the equipment used, being a furnace, an air stripping knife and a supporting bar which sought to replicate the tension of a commercial line. The Nolan thesis describes that oxide was cleared from the surface of the bath using a scraper. The Nolan thesis discloses that the sample was withdrawn at a rate of a metre per second, and that the coating mass is only controlled on one side by the air knife. The sample was held horizontally by bulldog clips. 1191 Let me say something about short range coating thickness variations. Nolan did not take any steps to control short range coating thickness variation. He rejected samples that did not meet the desirable coating thickness range. Nolan used Fischer Deltascope to take measurements of the coating thickness. However, the intervals at which measurements were taken are not identified. The Nolan thesis does not describe how many measurements were taken, or describe steps to control coating thickness variations over 5 mm increments. 1192 Now Mr Rommal asserted that the Nolan thesis discloses the control of short range coating thickness variations, because a Fischer Deltascope was used. But Nolan was not controlling coating thickness variations. Rather he was discarding unacceptable samples. 1193 Let me say something about the distribution of Mg2Si. 1194 One cannot ascertain from the Nolan thesis how much Mg2Si is in the surface of the coating or in the surface region. The Nolan thesis reports the formation of large particles of Mg2Si above 0.5 wt.% Mg, which become more prominent with increasing Mg. Professor Marder concluded that above 0.5 wt.%, Mg2Si was present, which was coming out of the intermetallic layer. But there may be some Mg2Si at the surface region at 0.5 wt.% Mg. 1195 The aims of the project were to produce a product which did not have compromised formability or corrosion performance. It concludes that the only promising results were obtained with Mg additions, which showed significant improvement to the salt spray corrosion resistance of unpainted coatings and edge undercutting. Those improvements were more marked at higher Mg additions. The Nolan thesis concludes that although the salt spray resistance and edge undercutting of zincalume is increased by adding Mg, most markedly at 2.5 wt.% Mg, processing problems occur at 1 wt.% Mg. 1196 The Nolan thesis concludes that the addition of magnesium did not result in benefits which outweighed the detriments relating to coating ductility. The benefits were insufficient to warrant further investigation as a modifying element capable of improving the mechanical or corrosion properties of zincalume. It stated that whilst there were improvements to performance, there were associated detrimental effects that negated the benefits. 1197 In summary, neither the Nolan article nor the Nolan thesis: (a) relate to the use of the hot dip coating method of the kind disclosed in the claims of the 257 Patent; (b) deals with mottle or other surface defects; (c) disclose the control of short range coating thickness variation; (d) disclose that Mg2Si distribution should be controlled; (e) disclose any Mg2Si distribution; or (f) disclose coatings with the claimed alloy compositions. 1198 Neither the Nolan thesis nor the Nolan article nor the combination of both anticipate claims 1, 3 to 9 and 11 to 15 of the 257 Patent.

(e) Conclusion - the 257 Patent 1199 In summary, none of the prior art or the prior art products anticipate. I disagree with Dongkuk who contends that if the person skilled in the art followed the directions in the prior art documents then ordinary good manufacturing practice would mean that the claimed ranges of thickness variation would be achieved. I reject its contention that the patentee has simply claimed features possessed by the prior art products but which are not expressed in terms in the prior art documents.

(f) The 258 Patent 1200 Dongkuk says that each of claims 1, 2, 5, 6, 11, 12 and 17 to 25 of the 258 Patent has been anticipated. 1201 Dongkuk says that each of the prior art documents that I have just discussed above discloses the making of an Al-Zn-Si-Mg alloy coated steel strip wherein those elements are in the claimed ranges of the 258 Patent and involve the use of cooling rates well below the maximum cooling rates identified in the 258 Patent. Further, it is said that Nisshin discloses the use of Sr additions within the range identified in the 258 Patent. Dongkuk says that on the teaching of the 258 Patent, that is, that those matters would give rise to the claimed distribution of Mg2Si, then Nisshin, the Nolan article and/or Nolan thesis and Kurosaki must anticipate claim 1 of the 258 Patent. It says that to the extent the other asserted claims contain additional features, they are also disclosed in or would be the inevitable result of following a suggestion in Nisshin, the Nolan article and/or Nolan thesis and Kurosaki. 1202 Dongkuk pointed to the following evidence. 1203 It was noted in a 2007 BlueScope TechNote by Blanksby T et al titled "Cracking in 1.8-2% Magnesium-Containing 55%Al-Zn Coatings - Mechanisms and Strategies to Minimise" that ordinarily "[in] conventionally solidified coatings … the Mg2Si is located predominantly in the bottom half of the coating, probably due to nucleation at the alloy layer and solidification from the substrate outwards" (citations omitted). 1204 It says that this is consistent with the figures in the Nolan thesis and the Nolan article which demonstrate the Mg2Si phase growing from the intermetallic alloy layer, and not from nor apparently reaching the surface of the coating. 1205 Dongkuk says that this is also consistent with the evidence of Professor Marder that Mg2Si effectively nucleates from the alloy layer like a tree, with the bulk of the Mg2Si located in the "trunk" and lesser amounts in the "leaves and branches" at the top of the tree. 1206 This conventional position changes with high cooling rates. BlueScope's August 2007 trial reported in a presentation titled "Project Edge: Trial Results" dated September 2007 that the AM150 product (75gms per m2 per side) displayed mottling, but not until the cooling rate had reached 65°C per second. 1207 Consistently with the above, in the next BlueScope trial in March 2009 at low cooling rates no mottle was seen. This indicated a more conventional distribution of Mg2Si. In relation to this trial, Mr Renshaw gave the following evidence: MR RYAN: …I don't see any reference to mottle here at all, Mr Renshaw? MR RENSHAW: No. MR RYAN: Why would that be? MR RENSHAW: The upleg cooler on MCL5 is not capable of much more than 30 degrees C per second. MR RYAN: Yes? MR RENSHAW: And so we didn't expect to see mottle. So there was no active trial or experiment - - - MR RYAN: Yes? MR RENSHAW: - - - that we would conduct on that line at that time. The - however, that's not to say that we weren't on the lookout for it if it happened. MR RYAN: And in fact at 30 degrees Celsius per second you didn't see it, did you? MR RENSHAW: No, we wouldn't expect it. MR RYAN: Thanks. And is that - is that because you - you had realised from the August trial that we looked at, that you didn't really have a problem with mottle until you got to a temperature above 65 degrees Celsius? MR RENSHAW: Yes, that's right. 1208 The next trial was in November 2009. In respect of this trial Mr Renshaw gave the following evidence: MR RYAN: And once again there's no mention of mottle here. Is that because at the temperatures you had in mind for cooling - rather, the cooling rates that you had in mind for this trial, it was unlikely to be a problem? MR RENSHAW: That's partly, although we could push MCL4 to those sorts of cooling rates if we had to. However, there were other limitations on the line that prevented us from running at full speed, and we - the other - the other focus of this was the coating thickness for this trial going to be low. We were talking at - we were looking AM100 and 125 coatings primarily and the vast bulk was going to be AM100. 1209 So, according to Dongkuk, it must follow that a product made in accordance with samples 10 and 11 of Kurosaki, with coating masses of 50gms per m2 per side and 45gms per m2 per side respectively and made at cooling rates of only 15°C per second, would have the claimed distribution of Mg2Si. 1210 Dongkuk says that the same conclusion must follow in respect of a product made according to Nisshin where the coating mass is 40 to 120gms per m2 per side and the cooling rate is only 20°C per second. Dongkuk submits that if there be any doubt, in respect of a product made according to Nisshin with a mass of between 100 to 120gms per m2 per side that doubt must evaporate because of the presence of Sr in the Nisshin alloy which "makes it virtually impossible for the Mg2Si phase to nucleate on the quaternary alloy layer or on the surface oxide" (see p 16 lines 35 to 37 of the specification for the 258 Patent). 1211 In relation to the Nolan article and Nolan thesis, in addition to the evidence of the micrographs Dongkuk submits that the same result must in principle follow for products made according to Nolan because they had an average thickness of 25 micrometers and a cooling rate of only 12.3°C per second; 25 micrometers equates to an AZ150 product or a product having a coating mass of nominally 75 but up to 85gms per m2 per side coating thickness (see Australian Standard 1397-2001 "Steel sheet and strip - Hot dip zinc-coated or aluminium/zinc-coated"). 1212 Now Dr Prošek's resistance to Dongkuk's conclusions was based upon the absence of mention in the prior art documents of certain production parameters. He identified two examples, namely, temperature of the steel strip at the moment it enters the galvanising bath and temperature of the galvanising bath itself. 1213 But Dongkuk submits that these processing parameters are matters about which the person skilled in the art does not need to be told. It says that it is enough to know that the hot dip coating method is to be used. It says that the 258 Patent at p 2 lines 1 to 16 treats those matters as conventional. Similarly it says that the Berke patent (US patent no. 4,401,727 "Ferrous product having an alloy coating thereon of Al-Zn-Mg-Si alloy, and method") says that: The products of this invention can be prepared on a commercial scale employing a conventional continuous hot-dip coating line, as known in the art… 1214 Berke then goes on to give a very broad range of temperatures for the steel strip as it enters the bath and a very rough temperature for the bath itself: The actual temperature of the molten alloy bath for a commercial hot-dip coating line is maintained at about 50°F (22°C) above the melting point for the alloy composition of the bath… 1215 Further, Dongkuk says that Mr Renshaw did not indicate that any of Dr Prošek's parameters came into play in his expectation of mottle occurring or otherwise in the March and November 2009 trials. 1216 Dongkuk submits that the person skilled in the art following the directions in the prior art would not need to be expressly informed of these parameters but would adopt any available parameters within the broad range available in the hot dip metal coating method. 1217 Further, it says that to the extent that the 258 Patent teaches that minimising variations in coating thickness gives rise to the claimed distribution of Mg2Si particles then the exercise of ordinary care in working Kurosaki, the Nolan article and/or Nolan thesis and Nisshin would result in the claimed distribution of Mg2Si. 1218 I would reject Dongkuk's arguments. Dongkuk asks me to draw inferences. But those inferences are based on the erroneous assumption that each of the "prior art products" had the claimed distribution of Mg2Si particles, because each had cooling rates lower than the maximum rates taught in the 258 Patent and lower than the rates which presented a problem for BlueScope in its line trials. But the assumption is not made good. 1219 So for the reasons set out above, Kurosaki does not anticipate claims 1, 2, 5, 6, 11, 12 or 17 to 25 of the 258 Patent, Nisshin does not anticipate claims 1, 2, 5, 6, 11, 12 or 17 to 25 of the 258 Patent and the Nolan article and the Nolan thesis do not anticipate claims 1, 2, 5, 6, 11, 12 or 17 to 25 of the 258 Patent.

LACK OF INVENTIVE STEP 1220 Dongkuk asserts a lack of inventive step concerning claims 1, 3 to 9 and 11 to 15 of the 257 Patent and claims 1, 2, 5, 6, 11, 12 and 17 to 25 of the 258 Patent. 1221 For the purposes of this proceeding, the applicable version of ss 7(2) and (3) are: (2) For the purposes of this Act, an invention is to be taken to involve an inventive step when compared with the prior art base unless the invention would have been obvious to a person skilled in the relevant art in the light of the common general knowledge as it existed in the patent area before the priority date of the relevant claim, whether that knowledge is considered separately or together with the information mentioned in subsection (3). (3) The information for the purposes of subsection (2) is: (a) any single piece of prior art information; or (b) a combination of any 2 or more pieces of prior art information; being information that the skilled person mentioned in subsection (2) could, before the priority date of the relevant claim, be reasonably expected to have ascertained, understood, regarded as relevant and, in the case of information mentioned in paragraph (b), combined as mentioned in that paragraph. 1222 An invention is taken to involve an inventive step when compared to the prior art base unless it would have been obvious to a person skilled in the relevant art in light of common general knowledge as described in Minnesota Mining and Manufacturing Co v Beiersdorf (Australia) Ltd (1980) 144 CLR 253 at 292 per Aickin J as it existed in the patent area (the then s 7(2) of the Act) before the priority date, whether that knowledge is considered separately or together with information of the kind described in the then s 7(3). 1223 The term "obvious" means "very plain"; see Aktiebolaget Hässle v Alphapharm Pty Ltd (2002) 212 CLR 411 at [34] per Gleeson CJ, Gaudron, Gummow and Hayne JJ and Lockwood Security Products Pty Ltd v Doric Products Pty Ltd (No 2) (2007) 235 CLR 173 at [51]. The inventive element needed to sustain a patent can be small. A "scintilla of inventiveness" will be sufficient and "no smallness or simplicity will prevent a patent being good" (Meyers Taylor Pty Ltd v Vicarr Industries Ltd (1977) 137 CLR 228 at 249 per Aickin J). 1224 Relevant further content has been given to determining obviousness in The Wellcome Foundation Ltd v VR Laboratories (Aust) Pty Ltd (1981) 148 CLR 262 at 286 per Aickin J in stating: whether the hypothetical addressee faced with the same problem would have taken as a matter of routine whatever steps might have led from the prior art to the invention, whether they be the steps of the inventor or not. 1225 Further, in relation to experiments, his Honour said (at 280 and 281): In the present case it was admitted by the respondent that the test of obviousness was an objective one, but it was argued that evidence of a subjective character was admissible. That is no doubt true in some cases because expert witnesses are often properly asked whether they found a particular invention "surprising" to them. That however does not answer the question whether evidence of the steps which the patentee took is relevant and therefore admissible. Evidence of what was in the patentee's mind may be admissible as evidence of the state of the art, but could seldom be otherwise admissible. Evidence of what he did by way of experiment may be another matter. It might show that the experiments devised for the purpose were part of an inventive step. Alternatively it might show that the experiments were of a routine character which the uninventive worker in the field would try as a matter of course. The latter could be relevant though not decisive in every case. It may be that the perception of the true nature of the problem was the inventive step which, once taken, revealed that straightforward experiments will provide the solution. It will always be necessary to distinguish between experiments leading to an invention and subsequent experiments for checking and testing the product or process the subject of the invention. The latter would not be material to obviousness but might be material to the question of utility. 1226 So, would the addressee faced with the same problem have taken, as a matter of routine, whatever steps might have led from the prior art to the invention? That question has an affinity with the Cripps question posed in Olin Mathieson Chemical Corporation v Biorex Laboratories Ltd [1970] RPC 157 and paraphrased by French CJ in AstraZeneca AB v Apotex Pty Ltd (2015) 257 CLR 356 at [15] in the following terms: Would the notional research group at the relevant date, in all the circumstances, which include a knowledge of all the relevant prior art and of the facts of the nature and success of [the existing compound], directly be led as a matter of course to try [the claimed inventive step] in the expectation that it might well produce a useful alternative to or better drug than [the existing compound]? 1227 Further, the plurality said in Aktiebolaget Hässle (at [58]) that: The tracing of a course of action which was complex and detailed, as well as laborious, with a good deal of trial and error, with dead ends and the retracing of steps is not the taking of routine steps… 1228 Further, it is erroneous to characterise as obvious the variation of all parameters or the trying of all choices until one proves successful, where the prior art did not point to it. Similarly, it is erroneous to characterise as obvious the exploration of a new technology or a promising field of experimentation, where the prior art gave no more than general guidance. 1229 Impermissible hindsight should be avoided in determining whether a claimed invention lacks an inventive step. In Aktiebolaget Hässle (at [21] and [78]) the importance of avoiding hindsight was reinforced in the following terms: [T]he warnings in the authorities against the misuse of hindsight are not to be repeated as but prefatory averments and statements of trite law. The danger of such misuse will be particularly acute where what is claimed is a new and inventive combination for the interaction of integers, some or all of which are known. It is worth repeating what was said by Lord Diplock in Technograph Printed Circuits Ltd v Mills & Rockley (Electronics) Ltd: "Once an invention has been made it is generally possible to postulate a combination of steps by which the inventor might have arrived at the invention that he claims in his specification if he started from something that was already known. But it is only because the invention has been made and has proved successful that it is possible to postulate from what starting point and by what particular combination of steps the inventor could have arrived at his invention. It may be that taken in isolation none of the steps which it is now possible to postulate, if taken in isolation, appears to call for any inventive ingenuity. It is improbable that this reconstruction a posteriori represents the mental process by which the inventor in fact arrived at his invention, but, even if it were, inventive ingenuity lay in perceiving that the final result which it was the object of the inventor to achieve was attainable from the particular starting point and in his selection of the particular combination of steps which would lead to that result." … After its review of the evidence, the Full Court concluded that Astra's "development" of the formulation "was essentially an exercise in trying out various known possibilities until the correct solution emerged" (emphasis added). That view of the matter wrongly takes as the starting point the assumed result. It succumbs immediately to the seduction of hindsight. Also, the notion of trying out possibilities invites the repetition of criticisms made earlier in these reasons. (Citations omitted.) 1230 In Lockwood (No 2) (at [46]) the High Court repeated the caveat against the misuse of hindsight. Clearly, any inordinate use of hindsight is likely to conceal or gloss over all of the problems, blind alleys and choices of options encountered by the patent applicant along the path to the invention. 1231 Further, it is self-evident that problems with hindsight are even further elevated where the claimed invention concerns the application of known principles. 1232 Further, little weight should be given to expert evidence that a claimed invention was obvious if the expert was provided with a copy of the patent or other relevant information before giving their evidence. At the least lesser weight is to be given to the evidence of experts asserting an invention to be obvious after they have reviewed the patent or been provided with other information concerning the state of the art. Undoubtedly, there is a need for caution where an expert asserting obviousness knew both the problem and the solution. 1233 Let me say something further about common general knowledge. Section 7(2) first requires consideration of what would have been obvious to a person skilled in the relevant art in the light of the common general knowledge as it existed before the priority date, putting to one side for the moment s 7(3) information. Common general knowledge is knowledge "generally known and accepted without question by the bulk of those who are engaged in the particular art" (British Acoustic Films Ld v Nettlefold Productions (1936) 53 RPC 221 at 250 per Luxmoore J). Information cannot be treated as part of the common general knowledge unless there is evidence of its general acceptance and assimilation by persons skilled in the art. And information does not constitute common general knowledge merely because it might be found for example in a journal, even if widely read by such persons. Further, as Luxmoore J said at 250: In my judgment it is not sufficient to prove common general knowledge that a particular disclosure is made in an article, or series of articles, in a scientific journal, no matter how wide the circulation of that journal may be, in the absence of any evidence that the disclosure is accepted generally by those who are engaged in the art to which the disclosure relates. A piece of particular knowledge as disclosed in a scientific paper does not become common general knowledge merely because it is widely read, and still less because it is widely circulated. Such a piece of knowledge only becomes general knowledge when it is generally known and accepted without question by the bulk of those who are engaged in the particular art; in other words, when it becomes part of their common stock of knowledge relating to the art. Whatever else common general knowledge may be, it has never in my judgment included public knowledge of particular documents reports or scientific papers and the like. The knowledge of a number of individuals that a particular suggestion or particular suggestions has or have been made for the use of biasing in a particular apparatus, or a number of particular apparatus, cannot be held to be common general knowledge. It is certainly difficult to appreciate how the use of something which has in fact never been used in a particular art can ever be held to be common general knowledge in the art. 1234 Further, as stated in Minnesota Mining by Aickin J (at 292), the notion of common general knowledge: involves the use of that which is known or used by those in the relevant trade. It forms the background knowledge and experience which is available to all in the trade in considering the making of new products, or the making of improvements in old, and it must be treated as being used by an individual as a general body of knowledge. 1235 So it must be knowledge that is known and available to all in the trade or at least the bulk of those who are engaged in the relevant art. Accordingly, information ascertainable by a routine literature search is not of itself taken to be common general knowledge. And patent specifications do not form part of common general knowledge without evidence that they have been absorbed into common general knowledge. 1236 Further, and as elucidated by Jagot J in Gilead Sciences Pty Ltd v Idenix Pharmaceuticals LLC (2016) 117 IPR 252 at [216] (affirmed in Idenix Pharmaceuticals LLC v Gilead Sciences Pty Ltd (2017) 134 IPR 1 per Nicholas, Beach and Burley JJ), it is erroneous to treat a document as being part of common general knowledge simply because skilled persons could readily locate and assimilate its contents. Her Honour went on to explain (at [217]): It may be accepted that instant recall of an article is not required. This does not mean, however, that documents found by searching for a subject-matter, rather than by some form of recall or reminder of what is already known to exist, are common general knowledge. This is so irrespective of the fact that experts in the field read widely. Further, it is not the case that mere publication and republication proves that a document and its contents have entered the common general knowledge. Nor is it the fact that a document and its contents necessarily form part of the common general knowledge merely because one expert knows or has managed to locate it and assimilate its contents. Such a document may or may not form part of the common general knowledge. The relevant inferences are to be drawn on the basis of the whole of the evidence. 1237 Let me say something at this point on s 7(3) albeit briefly. In addition to using common general knowledge on a stand-alone basis, common general knowledge can be aggregated with s 7(3) information. That part of the prior art base which is common general knowledge and the information referred to in s 7(3) are considered for the purpose of looking forward from the prior art base to see what the skilled person is likely to have done when faced with a particular problem. Now in a case where the problem is known and is part of the common general knowledge, the problem may be similar to that which the patentee claims to have solved with the claimed invention. But where the problem addressed by the patentee does not form part of common general knowledge, the relevant starting point is the prior art base, but not including the problem as identified in the patent specification. As was noted in AstraZeneca AB v Apotex Pty Ltd (2014) 226 FCR 324 by the plurality (at [203]): If the problem addressed by a patent specification is itself common general knowledge, or if knowledge of the problem is s 7(3) information, then such knowledge or information will be attributed to the hypothetical person skilled in the art for the purpose of assessing obviousness. But if the problem cannot be attributed to the hypothetical person skilled in the art in either of these ways then it is not permissible to attribute a knowledge of the problem on the basis of the inventor's "starting point" such as might be gleaned from a reading of the complete specification as a whole. 1238 The purpose of the inquiry is to determine whether the invention is obvious to solve the perceived problem, looking forward from the prior art base. But of course this may not have been the patentee's starting point. 1239 Let me now refer to what I said on reasonable ascertainability in SNF (Australia) Pty Ltd v BASF Australia Ltd (2019) 140 IPR 276; [2019] FCA 425 at [1082] to [1089]. As at the priority date, in order for information in addition to common general knowledge to be able to be taken into account in assessing inventive step, it was a requirement pursuant to s 7(3) (in its then terms) that a person skilled in the art could, before the priority date, be reasonably expected to have ascertained, understood, and regarded as relevant that information. 1240 The word "ascertained" means "discovered or found out". The fact that a document has been published does not mean that a person skilled in the art could be reasonably expected to have ascertained that information. The relevant question is whether the document was published in such a manner or form that it could reasonably have been expected to be found by a person skilled in the art. 1241 In assessing whether a person skilled in the art could be reasonably expected to have ascertained the information, it is important to consider the characteristics of the person skilled in the art, the nature of the problem, and the information typically used by the persons skilled in the art. Section 7(3) does not assume an ascertainability by any and all skilled persons, of whatever description, of all publicly available prior art documents anywhere in the world. 1242 Let me say something specifically about patent searches. 1243 There may be situations where it would not be reasonable to have an expectation that a person skilled in the relevant art would conduct a search of the patent literature (Commissioner of Patents v Emperor Sports Pty Ltd (2006) 149 FCR 386 at [34]). 1244 Further, the mere fact that some participants in the field might undertake patent searches is not sufficient to establish a reasonable expectation of ascertainment. In Delnorth Pty Ltd v Commissioner of Patents (2013) 100 IPR 175, Nicholas J refused to find that a person skilled in the art could be reasonably expected to have ascertained the relevant patents, even though there was evidence of patent searching and substantial R&D expenditure, because inter-alia (at [53]): Mr Turner's evidence was vague as to the nature of the patent searches undertaken by or on behalf of his company during and after the mid-1980s, and the circumstances in which they were undertaken. In particular, it said nothing about the scope of such searches including how they were targeted or how far back in time they extended. 1245 Further, it is important to have regard to the jurisdiction in which any prior patents, asserted to constitute s 7(3) information, were filed. For example, in JMVB Enterprises Pty Ltd v Camoflag Pty Ltd (2006) 154 FCR 348 (at [77]), the Full Court held that it could not, on the facts of that case, be reasonably expected that a person skilled in the art in Australia would have ascertained patents filed in New Zealand: [T]hose contentions ignore the distinction between what might reasonably be expected of a prospective seller of caravans in New Zealand, on the one hand, and the notional person skilled in the field of campervan design in Australia. There was no evidence that any designer would actually contemplate conducting a patent search in New Zealand. 1246 Further, it is important to consider the age of the asserted s 7(3) information. It is conceivable that searches undertaken might extend to patents granted many years before the priority date of the patent in suit. But this may not be sufficient to establish a reasonable expectation that a person skilled in the art would search such old patents for the purpose of solving the problem to which the patent in suit was directed (Delnorth at [54]). 1247 Further, it is not sufficient for a party seeking to rely upon a prior patent as s 7(3) information to establish that a person skilled in the art "had some familiarity with the patent literature as at the priority date" (Delnorth at [55]). The question is whether it could be reasonably expected that a person skilled in the art would have ascertained the specific patents which were asserted to constitute s 7(3) information. Accordingly, if it is asserted that a person skilled in the art would have ascertained a prior patent by undertaking a routine search, then unless an inference could be drawn, evidence would generally be required that the person skilled in the art may reasonably be expected to have done such a search. 1248 Further, on the question of reasonable ascertainability, the requirement of "reasonableness" is applied to each of the "ascertained", "understood" and "regarded as relevant" limbs of the s 7(3) test. 1249 In Aspirating IP Ltd v Vision Systems Limited (2010) 88 IPR 52, it was explained at [457] to [458] that whether something could be reasonably expected requires a prediction and that in the context of s 7(3) the question is whether, having regard to the evidence, it may be reasonably predicted that the hypothetical non-inventive skilled worker faced with the relevant problem before the priority date would have ascertained, understood and regarded as relevant the particular s 7(3) information in question. 1250 Further, the Full Court in Commissioner of Patents v Emperor Sports Pty Ltd (2006) 149 FCR 386 in considering the "ascertained" limb of s 7(3), noted at [31]: Section 7(3) does not assume an ascertainability by any and all skilled persons, of whatever description, of all publicly available prior art documents anywhere in the world. Nor does it assume that the skilled person has found the document in question, so that the only question is whether he or she has understood it and regarded it as relevant. Such a construction ignores the elements of expectation and reasonableness, as applied to the particular skilled person. 1251 In Emperor Sports, the Full Court concluded that the asserted prior art documents in that case, being seven United States patents, were not part of the prior art base as extended by s 7(3). This was because the relevant skilled person could not reasonably have been expected to have ascertained the patents. In that case, the person skilled in the art was a Rugby League or Australian Rules Football coach, referee, umpire or administrator. The Full Court held at [35]: Simply stated, we think it self-evident that it could not be reasonably expected that a Rugby League or Australian Rules coach, referee, umpire or administrator would conduct a search in the United States Patent Office. Such an expectation would be fanciful rather than reasonable. 1252 The Full Court in Emperor Sports held that "ascertained" in s 7(3) is used in the sense of "[t]o find out or learn for a certainty by experiment, examination, or investigation; to make sure of, to get to know" (at [29]). The Court observed that this interpretation was consistent with the word "find" as suggested by the IPAC Committee in its recommendation for what became s 7(3). The IPAC Committee used the expression "reasonably have been expected to find, understand and regard as relevant" (at [30]). The Court noted that the Commissioner accepted that the change from "find" to "ascertained" appeared to be no more than a matter of drafting stylistic preference (at [30]). 1253 Further, a mere "possibility" of an alleged s 7(3) document being ascertained or treated as relevant is not sufficient for the purposes of s 7(3). The relevant question is to be posed in terms of "would find" rather than "could find".

(a) Dongkuk's arguments 1254 Dongkuk has submitted that it is open to combine common general knowledge with either Kurosaki or Nisshin to arrive at the invention claimed in either the 257 Patent or the 258 Patent. It says that it is open to do so since the evidence shows that each piece of prior art is a document which the person skilled in the art could reasonably be expected to have ascertained, understood and regarded as relevant. Dongkuk says that the first search of Mr Gregory McKenzie, a patent attorney for Dongkuk, turned up the Berke patent. He then conducted a citation search of Berke and turned up multiple copies of Kurosaki. He then conducted a classification search based on the citation search and turned up Nisshin and Kurosaki. Dongkuk says that the Berke patent was well known in the field and that a patent citation search from a well-known publication was a reasonable search strategy as was a consequent classification search. In any event it says that it is clear that in this field dominated by large industrial enterprises, each player keeps a close eye on the patenting activity of competitors and has dedicated patent groups or experienced librarians to do so. It says that BlueScope was aware of Kurosaki. And it points out that the person skilled in the art in the present case is a member of a team that would have knowledge of steelmaking and metallurgy and would be familiar with the basic features of the galvalume/zincalume coated product and the process for making it at the priority date. 1255 Accordingly, it says that common general knowledge may be combined with either of Kurosaki or Nisshin, considered separately. And it says that Mr Rommal's evidence shows that by combining either Kurosaki with common general knowledge or Nisshin with common general knowledge, one would as a matter of routine perform the invention as claimed in each of the 257 and 258 Patents if the promised outcome of the processing conditions and Sr additions were accurate. 1256 It says that Mr Rommal was the only expert witness who provided an opinion on inventive step without being tainted by hindsight. Bluescope's witnesses had each seen the 257 and 258 Patents. Now much of Mr Rommal's cross examination was directed to undermining his selection of specific examples in Kurosaki and Nisshin, especially samples 10 and 11 of Table 1 of Kurosaki. But Dongkuk submits that it is not to the point that Mr Rommal would have selected those compositions together with other compositions in Kurosaki. It says that each one of samples 1 to 14 of Kurosaki is expressly an example of Kurosaki's "present invention". It says that each one is, therefore, recommended over the comparative samples 15 to 30. It says that each one is an obvious choice for a useful alternative to galvalume. 1257 Further, Dongkuk says that none of the subsidiary claims is saved from the conclusion of obviousness by the addition of well-known integers which may not be expressed in Kurosaki or Nisshin. Thus, for example, claim 5 of the 257 Patent claims a coating thickness of 22 micrometres and a thickness variation of no more than 5 micrometres above that stated 22 micrometre coating thickness. But Dongkuk says that is simply to state a particular thickness variation within the range of claim 1. Claim 8 of the 257 Patent claims "[t]he method defined in any one of claims 1 to 6 comprising selecting the cooling rate for coated strip exiting the coating bath to be less than 50°C/sec for coating masses of 75-100 grams per square metre of strip surface per side". Dongkuk says that samples 10 and 11 of Kurosaki are cooled at less than 50°C per second but they do not involve coating masses of 75 to 100gms per m2 of strip surface per side. Further, the question arises whether there would be any difficulty overcome or barrier crossed in making sample 10 or 11 of Kurosaki with a coating coverage of 75 to 100gms per m2. But Dongkuk says that there would not be. 1258 In summary, Dongkuk submits that each of the asserted claims is invalid for obviousness.

(b) Analysis 1259 Let me analyse these arguments. 1260 Now Dongkuk originally pleaded that the invention(s) was obvious in light of common general knowledge alone, in light of common general knowledge and Kurosaki or in light of common general knowledge and Nisshin. But at trial, Dongkuk did not press its case for obviousness based on common general knowledge alone. 1261 Let me turn first to Kurosaki and say something about reasonable ascertainability. 1262 I do not accept that a skilled addressee could reasonably be expected to have ascertained Kurosaki. 1263 BlueScope's witness Mr George Mokdsi, a patent researcher who followed the instructions from Dr Prošek and Mr Dutton, did not find the Kurosaki patent in his searches. And although Dongkuk's witness, Mr McKenzie did find the Kurosaki patent, he did not do so using search terms or strategies identified by the skilled addressee. 1264 Mr Rommal's evidence in relation to the search terms was as follows: The search would have looked for combinations of terms like corrosion, coating, ductility or formability, Al or Aluminum or Aluminium, Zn or Zinc, Mg or Magnesium, but the librarian would have structured the query based on her experience with similar searches. It may also have been possible to search for publications that referenced the Berke patent, though again, what was possible and the mechanism for doing it was the purview of the librarian. 1265 Further, Mr McKenzie did not search for the terms identified by Mr Rommal. Rather, he searched for terms which he had himself identified as relevant based on his own review of Berke, and the documents identified in a citation search for Berke. He explained his approach in the following exchange: MR McKENZIE: [F]rom my reading of - after doing the literature survey and reading through the other patents and what they were targeting, what appeared to be the core inventive concept from looking at, first of all, the literature search and then looking at the other results, it appeared that MT - Mg2Si was the invention. MS CUNLIFFE: But as you say, that's your opinion based on all of the patent literature you reviewed? MR McKENZIE: Yes, as I was - - - MS CUNLIFFE: It wasn't input from the expert witness? MR McKENZIE: Yes. Yes, as I started reading literature, that came to the front as what this was about. 1266 Now Mr McKenzie accepted that usually he would undertake a search in conjunction with the person providing instructions, so that the subject matter expert could provide feedback. But in the present case he had received no feedback. Accordingly, he substituted his own judgment for relevance for that of Mr Rommal, the subject matter expert. 1267 Moreover, Mr McKenzie did not simply conduct a citation search of Berke. Rather, he searched for all patents which cited Berke, all patents which were cited by patents which cited Berke, and all patents which cited patents which cited Berke. The results took up more than 100 pages in one of his appendices. 1268 Further, although Mr McKenzie found Kurosaki, there is no evidence that Mr Rommal would have selected Kurosaki from the more than 100 pages of results. 1269 Further, Dongkuk's contention that the evidence indicated that each player keeps a close eye on the patenting activity of competitors is overstated. Mr Dutton's evidence was that he did not know what the patent group did because he did not have personal experience. Mr Rommal says that he reviewed patents, but not how the patents he reviewed were identified. 1270 Further, none of the experts had seen Kurosaki before the commencement of these proceedings. 1271 In my view the evidence does not demonstrate on the balance of probabilities that the skilled addressee would have ascertained Kurosaki. 1272 Let me now say something about the Berke patent which I accept was common general knowledge. 1273 Berke disclosed that Mg could be added to the galvalume coating, together with high levels of Si. The broadest disclosure was that one would add Mg between 3 and 20 wt.% and Si between 3 and 15 wt.%. The preferred ranges are 5 to 15 wt.% of each of Mg and Si. That range was based on accelerated corrosion testing, salt spray testing and another test. 1274 The most preferred composition included Mg and Si each in the amount of 10 wt.%. Panels of the invention were listed in Table 1. Sample 3 contained 18 wt.% Mg and 6 wt.% Si and sample 4 contained 7.4 wt.% Mg and 8 wt.% Si. Berke disclosed that to achieve improved corrosion, which was tested in a sulphur dioxide test, there should be more than 5 wt.% Si and more than 4 wt.% Mg. 1275 Berke identified visual features including colour, texture, reflectivity, discolouring, roughness, satin shine finish and spangle. But Berke made no reference to mottle. Berke taught that where there was more Si in the composition, corrosion resistance and salt spray resistance would improve by a factor of two over galvalume. 1276 Now assume that the skilled addressee was set the task of developing an Al-Zn-Si-Mg alloy coated strip with good corrosion resistance, good coating ductility and minimal surface defects. The skilled addressee would understand from Berke that the optimum composition for each of magnesium and silicon was 10wt.%. Although the skilled addressee might be uncertain of the optimal composition pending field trials, he would approach the task in the expectation that the Mg and Si content would be high. But the skilled addressee could not predict what would be the best composition in any particular outdoor corrosion environment. A skilled addressee who was set the task of arriving at an improved Al-Zn-Si-Mg coated strip would come to the task seized with the knowledge in Berke and conclude that a suitable composition would include 10 wt.% Mg and 10 wt.% Si. 1277 Let me now deal with Mr Rommal's knowledge. 1278 Mr Rommal's evidence is that while he was employed at Bethlehem Steel he worked on Project Four Star from 1986 to 1991. He studied a variety of compositions and other process parameters and their effect on structural appearance, formability and corrosion performance to try and find an optimum combination that would be an improvement over galvalume. 1279 Project Four Star started with the Berke patent. After many years of work including work undertaken before Mr Rommal joined the team, the Project Four Star team formed the view that it should move away from the Berke patent to reach the Project Four Star composition. Mr Rommal confirmed that this work was confidential to Bethlehem Steel. 1280 The composition that emerged from the work in Project Four Star was Al from 50 to 55%, Mg 5%, Si 3% and the balance Zn. Mr Rommal conceded that the details of individual results in Project Four Star were not widely known because it was a proprietary development, and that it was his practice not to answer any specific questions from the galvalume producing community at large about Project Four Star. 1281 Now Dongkuk's inventive step case principally focuses on Mr Rommal's evidence. He was given the task by Dongkuk's solicitors of developing an Al-Zn-Si-Mg coated strip with good corrosion resistance, good coating ductility and minimal surface defects. 1282 But unfortunately Mr Rommal's evidence on inventive step took account of the idiosyncratic knowledge he had acquired whilst working on Project Four Star. 1283 When Mr Rommal initially responded to the task without regard to any prior art, he proposed a composition of Al 50 to 55 wt.%, Mg 5 wt.%, Si 3 wt.%, the remainder Zn and no Sr. This was the best of the many Project Four Star compositions which had been trialled. Mr Rommal explained that because of his knowledge of Project Four Star, he shied away from the higher end of Mg and Si, because he knew that those compositions did not provide good outdoor corrosion test results. But Mr Rommal accepted that a skilled addressee without his idiosyncratic knowledge would not shy away from the top end of the Si and Mg ranges. Mr Rommal's evidence was that a person without his knowledge from Project Four Star, and approaching the same task without undertaking experiments, would expect the amount of Si in the composition to be 10% and the amount of Mg in the composition to be 10%, although this would be a risky proposition without further experimentation. Such a person would not be able to predict what the best composition in any particular outdoor exposure environment would be or to predict an optimal composition based on Berke. 1284 Now when Mr Rommal first considered Kurosaki in response to the task, which was before he had seen the 257 and 258 Patents, he proposed a composition of 50 to 55 wt.% Al, 37 to 45.5 wt.% Zn, 3 to 5 wt.% Mg, 1.5 to 3 wt.% Si, and no Sr. 1285 When he first considered Nisshin in response to the task, he proposed a composition of 50 to 55 wt.% Al, 3 to 4 wt.% Mg, 1.6 wt.% Si, 0.01 to 1 wt.% Sr, and the balance Zn. 1286 Subsequently and after reading the 257 and 258 Patents, Mr Rommal gave evidence that he would also develop compositions based on samples 10 and 11 of Kurosaki. Sample 10 had 46% Al, 50.9 wt.% Zn, 1.5 wt.% Mg, 0.6 wt.% Si and no Sr. Sample 11 had 50 wt.% Al, 44.9 wt.% Zn, 3 wt.% Mg, 1 wt.% Si and no Sr. 1287 Now as is clear, Mr Rommal did not mention samples 10 and 11 of Kurosaki in his earlier evidence. And each of samples 10 and 11 falls outside the ranges of the composition Mr Rommal had initially selected. But some of samples 1 to 9 fell within this range. 1288 Ultimately Mr Rommal's evidence was that he would consider samples 1 to 9 and 12 but would also pursue samples 10 and 11. He would not prioritise a particular sample over another one. He would not discount samples 10 and 11. But by the time that Mr Rommal nominated samples 10 and 11, Mr Rommal had read the 257 and 258 Patents and commented on them. 1289 Further, after reading the 257 and 258 Patents, Mr Rommal gave evidence that he would develop a different composition based on Nisshin with 50 to 55 wt.% Al, 3 to 4 wt.% Mg, 1.6 wt.% Si, 0.1 wt.% Sr and Zn making up the balance. 1290 Further, Mr Rommal explained and conceded that the composition he initially selected without regard to the prior art and the compositions he initially based on Kurosaki and Nisshin took into account his experience gained whilst working on Project Four Star: So the composition in paragraph 19 of my second affidavit - it was "What I would develop after a consideration of the literature?" The question was not, "What would I develop, forgetting about Project Four Star and adding consideration of literature?" So this is a combination - 19 is a combination of what I knew from my own experience in Project Four Star, tempered by what is in the literature that I was provided at the time. Whereas the question that was put to me in the fourth affidavit was not around my internal knowledge from Project Four Star. Those questions were more around what I would do based on what I'm reading in the literature. … The questions put to me in these documents in paragraph 19 - that's Project Four Star knowledge plus reading the prior art documents. Because of my Project Four Star knowledge I am going to shy away from the higher magnesium and silicon compositions in the Berke patent and, in fact, in the Kurosaki work I'm going to shy away from the higher end because, with extended outdoor exposure tests, my knowledge from Project Four Star I know that those higher magnesium and silicon compositions did not produce good outdoor corrosion test results. … So hence my lower magnesium and silicon compositions that are -that are there. 1291 Indeed, Mr Rommal agreed that moving away from the top end of the Mg and Si ranges was not something that a person without his idiosyncratic knowledge would do. 1292 Further, Mr Rommal's experience of trying to develop a composition based on Berke is revealing in that Project Four Star trialled a very large number of Al-Zn-Si-Mg compositions, with the preferred composition including 5 wt.% Mg and 3 wt.% Si. 1293 Moreover, the matters which were not considered as part of Project Four Star were explained by Mr Rommal as follows: In my time on Project 4 Star, we did no experimentation on high Mg and Si formulations at higher cooling rates … We also did not explore the relationship between the distribution of Mg2Si and cooling rates/thickness variations at Bethlehem Steel because we never had the inclination of trying for a gradient in distribution of Mg2Si. … We did not experiment with Sr additions. 1294 I agree with BlueScope that Mr Rommal's evidence as to inventive step is not based on common general knowledge. Rather, the compositions he selected without regard to prior art and the compositions he initially selected based on Kurosaki and Nisshin, were based on idiosyncratic knowledge that he had acquired from his involvement in Project Four Star. 1295 Further, the second and third Kurosaki compositions that he selected and the second Nisshin composition also took into account his idiosyncratic knowledge, as is apparent from the low levels of Mg. And I also agree with BlueScope that these selections were additionally infected by hindsight. Mr Rommal by then had the 257 and 258 Patents. 1296 In my view, Mr Rommal's evidence must be given little weight on the inventive step question. 1297 Let me now draw some principal conclusions. In summary in my view the invention claimed in the 257 Patent or the 258 Patent is not obvious in the light of Kurosaki. I say this for the following reasons. 1298 Kurosaki discloses to the skilled addressee that bulky and scaly Mg2Si is preferred to improve corrosion resistance. The teaching of Kurosaki was that the important property of corrosion resistance was particularly significant when Mg and Si were high within their appropriate ranges. That teaching was consistent with the disclosure in Table 1. Further, the authors disclosed that the preferred range of Mg was 3 to 10 wt.% and of Si was 3 to 10 wt.%, and that bulky and scaly Mg2Si produced more satisfactory results from a corrosion resistance standpoint. The skilled addressee would therefore understand that it was desirable to have more Mg2Si particles. 1299 In my view samples 1 to 9 were consistent with that teaching, and the skilled addressee would select samples 1 to 9. 1300 Now although sample 12 (with only scaly Mg2Si) also performed well, it was the exception. The skilled addressee would appreciate, given that a wide scale for evaluating corrosion resistance was adopted, that sample 12 may have performed less well than samples 1 to 9. 1301 Further, samples 10, 11 and 12 were also inconsistent with Berke, because the level of Si in each was outside the level in Berke. 1302 In my view a skilled addressee reading Kurosaki in light of his common general knowledge, including Berke, would look to samples 1 to 9 as the preferred examples. He would appreciate that samples 1 to 9 were consistent with the teaching in Kurosaki that Si should be at least 3 and up to 10 wt.%. The Kurosaki specification informs the reader that samples 1 to 9 disclosed the best form of Mg2Si according to Kurosaki (bulky-scaly). That disclosure would be reinforced by the skilled addressee's knowledge of Berke. 1303 Further, the skilled addressee would try to adopt an Al:Zn ratio close to 1:1.25. And the skilled addressee would appreciate that samples 1, 2 and 4 fell within Berke's recommended ratio of Al:Zn of 1:1.5. 1304 Further, a skilled addressee would follow the teachings of Kurosaki and develop a product with high proportions of Mg2Si which would form in products where Mg was 3 to 10 wt.% and Si was 3 to 10 wt.%. 1305 Further, samples 10 and 11 did not include bulky and scaly Mg2Si. Moreover, samples 10 and 11 were inferior in relation to corrosion resistance against each of the parameters of salt corrosion resistance, painted corrosion resistance and outdoor exposure tests. Further, as BlueScope submitted, there was a disconnect between sample 10 and column 4, which disclosed that it was desirable to use Mg in the amount of 3 to 10 wt.%. Sample 10 also fell outside Berke's claimed ratio of Al:Zn. 1306 Now I note that Mr Rommal also relied on sample 23 to provide support for his selection of samples 10 and 11. He did so because he considered sample 23 to be the closest material in the study to galvalume. Mr Rommal considered samples 10 and 11 to have better corrosion performance than sample 23. But it appears that sample 23 was not the galvalume composition, because the coating mass of sample 23 was much thinner than the mass used on galvalume. Mr Dutton explained that the coating of sample 23 was roughly half of the galvalume coating, and that Bethlehem Steel had found that coating thicknesses below that level would not produce the desired dendrite arm spacing or circuitous microstructure and would fail early. Now Mr Rommal accepted that sample 23 was thinner than any galvalume product which had been commercialised, and that coatings of the thickness of sample 23 had experienced this problem at a cooling rate of 20ºC/sec. In any event, Mr Rommal accepted that samples 1 to 9 performed better than sample 23. In summary, Mr Rommal's reliance on sample 23 went nowhere. 1307 Further, although Mr Rommal gave evidence that he would pursue sample 10 (46 wt.% Al, Zn 50.9 wt.%, Mg 1.5 wt.% and Si 0.6 wt.%) and sample 11 (50 wt.% Al, 44.9 wt.% Zn, 3 wt.% Mg, Si 1 wt.% and Sr nil), he accepted that those approaches would be inconsistent with the teaching of Kurosaki as a whole concerning the compositions which provided the best corrosion resistance, and were outside the range of Berke. 1308 I agree with BlueScope that in light of the fact that samples 10 and 11 were inconsistent with Berke and the teaching of Kurosaki, the skilled addressee without Mr Rommal's idiosyncratic knowledge base would not choose them for development. 1309 Further, Mr Rommal, who knew a considerable amount about Al-Zn-Mg-Si alloys, did not have the requisite expectation of success in relation to these samples. His evidence was that it was obvious to try these compositions. Mr Rommal was aware from his experience with trying to make a successful product based on Berke that accelerated corrosion tests were not necessarily reliable. Mr Rommal explained that he would not know until he tested the compositions whether he would get a product that met his objective of being an improvement or a useful alternative to galvalume. Mr Rommal's evidence was that the data in Kurosaki did not convince him that he would be able to produce a commercially viable product. It only led him to some potentially interesting compositions that might be worthy of additional experimentation. But although these were worth exploring, he could not confidently expect that they would work. 1310 Dr Prošek's evidence is that he understood from Kurosaki that the best results would be obtained using Mg and Si in the amount of 3 to 10 wt.% and that Mg2Si could be present at the surface. Dr Prošek would not work at the lower ranges of Mg and Si because Kurosaki disclosed that bulky-scaly Mg2Si was preferable. Accordingly, Dr Prošek explained that he would have chosen to develop samples 1 to 9. 1311 Mr Dutton's evidence was that he would consider samples 1 to 9, and particularly samples 2, 3 and 5, which had the most bulky Mg2Si without reducing Zn and therefore reducing sacrificial protection. Mr Dutton considered that if the aim of the project was to develop a product with improved corrosion resistance, in a program with limited funds he would follow the disclosure of Kurosaki, and develop samples 1 to 9, which have bulky and scaly Mg2Si. 1312 In summary, in my view the skilled addressee, armed with Kurosaki, would not have appreciated that the inclusion of Mg2Si in the surface of the coating increased mottling and reduced ductility. The skilled addressee would not have had the knowledge that it was necessary to obtain a distribution of Mg2Si that located it away from the surface, and much less appreciated how this could be achieved. Moreover, the skilled addressee would have sought to make samples 1 to 9 of Kurosaki, each of which were compositions containing more bulky and scaly Mg2Si, including at the surface. 1313 Therefore it would not have been obvious to arrive at the invention(s) claimed in light of Kurosaki. 1314 Let me finally dispose of Nisshin. In my view, the invention claimed in the 257 Patent or the 258 Patent is not obvious in the light of Nisshin. Let me briefly explain my reasons. 1315 Nisshin discloses a solution to a wrinkle-like defect. The skilled addressee would not consider adding Sr to deal with any surface defect except the wrinkle-like defect, because Nisshin suggested that an Al-Zn-Mg-Si alloy would work well except for the wrinkle-like defect. 1316 Now notwithstanding Mr Rommal's lack of exposure to the wrinkle-like defect and lack of experience with Sr, Mr Rommal's first response to the task he was set after reading Nisshin was to prepare a composition in which he would decrease the amount of Mg from 5 wt.% to 3-4 wt.%, decrease the amount of Si from 3 wt.% to 1.6 wt.% and introduce Sr from 0.01 wt.% to 1 wt%. But after reading the 257 and 258 Patents and the evidence, Mr Rommal changed this composition to specify the inclusion of Sr in the amount of 0.1%. 1317 Mr Rommal's evidence was that he would trial an alloy coating without Sr and a coating with Sr to see if it was worth the expense of adding it. He explained: …if I took it as face value that the wrinkle-like defect is going to happen, then I would only use strontium and not even bother trialling it out, so I'm trying both. I would try both with and without strontium. If the strontium made the product look - look better and it's worth the cost? Great. We will use it. If the product looks the same with and without, then we would decide not to use it. 1318 But it is apparent from this evidence that Mr Rommal had no particular expectation of success in relation to the product. Mr Rommal's lack of confidence is unsurprising. He had reduced Mg from 5 wt.% to 3 to 4 wt.%, reduced Si from 3 wt.% to 1.6 wt.% and added Sr. Mr Rommal also accepted that if he did trial a coating with Sr, he would trial each of samples 27 to 30, which did not fall within the scope of the range claimed in claim 9 of the 257 Patent or claim 1 of the 258 Patent, as well as samples 20 to 22. It would seem that the effect of Mr Rommal's evidence is that, at best, samples 20 to 22 were worth trying, along with other options with and without Sr. But it is well apparent from his evidence that at the time he selected the candidate composition for trial he could not predict or reasonably expect that the trial was likely to result in a useful coating. 1319 In my view the skilled addressee reading Nisshin would understand the limited role Nisshin describes for Sr. In particular, the skilled addressee would understand that if they experienced a problem with Mg oxidation, which manifested as a wrinkle-like surface defect, Sr could be used to fix it in an amount up to 10,000 ppm. But the skilled addressee would not use Sr to control corrosion resistance, mottle in the case of the 257 Patent or ductility in the case of the 258 Patent. Moreover, Nisshin teaches that it was desirable to produce a microstructure with Mg2Si at the surface. The skilled addressee would adjust the processing parameters to achieve that end. 1320 Moreover, if the skilled addressee decided to trial any of the examples of Nisshin, which is unlikely in the absence of any wrinkle-like defect, they would trial samples 27 to 30. 1321 Further, even if the skilled addressee trialled samples 20 to 22 using the cooling rates specified, the skilled addressee would not achieve control of short range coating thickness variation or the claimed Mg2Si distribution. In any case, the skilled addressee would not undertake those trials with the requisite expectation of success. 1322 The claimed inventions are not obvious in light of Nisshin. 1323 In summary, Dongkuk's overall case on lack of inventive step must be rejected.

AMENDMENT APPLICATION 1324 BlueScope has applied to amend the 257 Patent to introduce into the body of the specification additional detail concerning the "special operational measures" used to control short range thickness variations in the coating. The proposed amendment does not affect the scope of the claims which are not sought to be amended. 1325 In support of the amendment application, BlueScope has relied upon evidence from: (a) Mr Renshaw, who as I have said was one of the inventors; (b) Mr Munt, a partner of Griffith Hack and BlueScope's external patent attorney responsible for prosecution of the 257 Patent and corresponding patents in other jurisdictions; (c) Mr Darren Mackenzie, General Counsel Australia & New Zealand for BlueScope; and (d) Mr Lopez, manager of Engineering Technology Mills & Coatings and chief mechanical engineer of BlueScope. 1326 The amendment application has been advertised in accordance with rule 34.41 of the Federal Court Rules 2011 (Cth). The Commissioner has not sought to be heard in relation to it. The amendment application has only been opposed by Dongkuk who has relied, inter-alia, on the evidence of Mr Salon. 1327 The proposed amendment introduces the following description into the body of the specification: In the context of the conventional hot-dip metal coating method and coating line described generally above on page 2 line 1 to page 3 line 12 of the specification, the gas wiping apparatus directs jets of wiping gas towards a coated steel strip with a molten alloy coating on the strip immediately after the coated strip leaves the coating bath. The jets of wiping gas control the thickness of the coating on the strip. A conventional coating line was used for the above-described line trials. In the case of the coating line used for the above-described line trials, the jets were situated approximately 350mm above the coating bath, approximately 14mm from the coated steel strip and applied a pressure of approximately 7 kPa. The special operational measures that may be used to keep the short range coating thickness variations under control include adjustments to the gas wiping apparatus at a coating thickness control station above the coating bath of the coating line, and/or the introduction of a stabiliser to stabilise the coated strip between the jets of wiping gas. The adjustment options for the gas wiping apparatus are known to the skilled person and include, by way of example, (a) adjusting by reducing the height of the wiping gas outlets of the gas wiping apparatus above the coating bath so that it is closer to the coating bath and/or (b) adjusting by reducing the distance between the wiping gas outlets and the coated strip whilst reducing the pressure of the wiping gas. A stabiliser (such as an electromagnetic strip stabiliser or an air flotation stabiliser) is known to the skilled person and stabilises the coated strip between the jets of wiping gas such that the distance between the jets of wiping gas and the coated strip remains constant. 1328 The proposed amendment provides more detail in relation to the special operational measures that may be adopted to control the short range coating thickness variations and thereby limit the risk of mottle. The proposed amended specification explains that these measures include adjustments to the gas wiping apparatus at a coating thickness control station above the coating bath of the coating line and the introduction of a stabiliser to stabilise the coated strip between the jets of wiping gas. The adjustment options for the gas wiping apparatus include reducing the height of the wiping gas outlets of the gas wiping apparatus above the coating bath so that the outlets are closer to the coating bath and reducing the distance between the wiping gas outlets and the coated strip whilst reducing the pressure of the wiping gas. The proposed amendment states that a stabiliser, such as an electromagnetic strip stabiliser or an air flotation stabiliser, is known to the skilled person and serves to stabilise the coated strip between the jets of wiping gas so that the distance between the jets and the coated strip remains constant. 1329 It would seem that the purpose of the amendment is to guard against the perceived risk that I might hold that the specification in its unamended form may not adequately disclose the best method known to BlueScope of performing the invention. As appears from other parts of my reasons, BlueScope was correct to perceive that risk, which has now eventuated. 1330 In my view the proposed amendments are allowable under s 102 (see s 105(4)) as in force at 13 March 2009, being the filing date of the 257 Patent; the current form of s 102(1) does not apply to the present case by reason of the transitional provision in Item 55(9)(b) of Schedule 1 of the Raising the Bar Act. The principal issue between the parties is whether as an exercise of discretion I should allow the present amendments. 1331 Dongkuk says that I should exercise my discretion pursuant to s 105(1) to refuse the amendments. Dongkuk has advanced four reasons. 1332 First, it says that the proposed amendments are futile because they cannot cure a failure to disclose the best method of performing the invention which was required to be disclosed at the filing date, or alternatively the date of grant. 1333 Second, it says that BlueScope has failed to provide full and frank disclosure. 1334 Third, it says that BlueScope has unreasonably delayed in making the amendment application. 1335 Fourth, it says that BlueScope has obtained an unfair advantage by failing to disclose the best method of performing the invention to the disadvantage to the public. 1336 Now BlueScope seeks to amend the specification by introducing new text to describe the "special operational measures". 1337 In order to understand the significance and effect of the proposed text, the unamended specification of the patent as it existed at the filing date of the specification needs to be considered. The unamended text which immediately precedes the proposed inserted text as it existed at the filing date is as follows: The applicant has also carried out line trials on 55%Al-Zn-1.5%Si-2.0%Mg alloy composition (not containing Sr) coated on steel substrates. The purpose of these trials was to investigate the impact of cooling rates and coating masses on mottling in the surface of the coatings. The trials covered a range of coating masses from 60 to 100 grams per square metre surface per side of strip, with cooling rates up to 90℃/sec. The applicant found two factors that affected the coating microstructure, particularly the distribution of Mg2Si particles in the coatings, in the trials. … The second important factor found by the applicant is the uniformness of coating thickness across the strip surface. The applicant found that the coating on the strip surface normally had thickness variations that are (a) long range (across the entire strip width, measured by the "weight-strip-weight" method on a 50mm diameter disc) and (b) short range (across every 25 mm length in the strip width direction, measured in the cross-section of the coating under a microscope with 500x magnification). In a production situation, the long range thickness variation is normally regulated to meet the minimum coating mass requirements as defined in relevant national standards. In a production situation, as far is the applicant is aware, there is no regulation for short range thickness variation, as long as the minimum coating mass requirements as defined in relevant national standards are met. However, the applicant found that short range coating thickness variations could be very high, and special operational measures had to be applied to keep the variations under control. It was not uncommon in the experimental work for the coating thickness to change by a factor of two or more over a distance as short as 5 mm, even when the product perfectly met the minimum coating mass requirements as defined in relevant national standards. This short range coating thickness variation had a pronounced impact on the Mg2Si particles in the surface of coatings. … Therefore, under the experimental conditions tested, the short range coating thickness variation should be controlled to no greater than 40% above the nominal coating thickness within a distance of 5mm across the strip surface to avoid mottling. [Text proposed to be inserted] 1338 I agree with Dongkuk that the following is self-evident from the unamended specification at the filing date. 1339 First, BlueScope sought to distinguish between long range thickness variation, which is "normally regulated to meet the minimum coating mass requirements as defined in relevant national standards", and short range thickness variation for which it said that there is "no regulation". 1340 Second, the specification stated that: short range coating thickness variations could be very high, and special operational measures had to be applied to keep the variations under control. It was not uncommon in the experimental work for the coating thickness to change by a factor of two or more over a distance as short as 5 mm, even when the product perfectly met the minimum coating mass requirements as defined in relevant national standards. 1341 I note that the relevant standards were met by controlling long range coating thickness variation. 1342 Third, it would seem to follow from the two points just made that BlueScope was saying that operating measures used to control long range thickness variation were different to short range thickness variation. 1343 In the circumstances I agree with Dongkuk that a person skilled in the art at the filing date would not understand what "special operational measures" were being referred to in the unamended specification, save that such a person would reasonably infer that the "special operational measures" were different to the operating measures known to regulate long range thickness variation. 1344 Indeed, by the proposed added text, BlueScope now years after the filing date seeks to say that the "special operational measures" to control short range coating thickness variation were not "special" but rather were known to skilled persons at the filing date. 1345 For the reasons discussed below, I refuse the amendment application.

(a) Statutory power and discretion 1346 Section 105 relevantly provides: (1) In any relevant proceedings in relation to a patent, the court may, on the application of the patentee, by order direct the amendment of the patent, the patent request or the complete specification in the manner specified in the order. (2) An order may be made subject to such terms (if any) as to costs, advertisements or otherwise, as the court thinks fit. (3) The patentee must give notice of an application for an order to the Commissioner, who is entitled to appear and be heard, and must appear if the court directs. (4) A court is not to direct an amendment that is not allowable under section 102. (5) The patentee must file a copy of an order within the prescribed period. (6) On the filing of a copy of an order, the patent, patent request or complete specification is to be taken to have been amended in the manner specified in the order. 1347 Let me repeat what I said in Meat & Livestock Australia Limited v Cargill, Inc (No 2) (2019) 139 IPR 47; [2019] FCA 33 at [343] to [353], [358] and [413]. 1348 It is convenient to first refer to a few cases dealing with the exercise of discretion under s 105(1). In Servier 2016 the relevant factors were conveniently summarised at [242] to [245] by Bennett, Besanko and Beach JJ in the following terms: While the power to amend should in appropriate circumstances be exercised in favour of the patentee, it bears mentioning that it will not always be possible to overcome a ground of revocation by an amendment. Accordingly, the ground of revocation sought to be overcome is also relevant to the way in which the discretion should be exercised. In the case of a failure to comply with the best method requirement, it would be necessary to take into account, in the exercise of the discretion, the reason for that obligation and the time at which it is meant to be fulfilled. A number of principles have been established and discussed in detail in the authorities in the United Kingdom and in this Court with respect to amendment of granted patents, relevantly and in summary: • The discretion exists for the benefit of the patentee. • The onus to establish that amendment should be allowed is on the patentee. • Generally, a permissible amendment (i.e. one which is permitted under the Act) will be allowed unless there are circumstances which would lead the court to refuse amendment. • The patentee must make full disclosure of all relevant matters. • The Court's focus is on a patentee's conduct, not the merit of an invention. • Amendment should be sought promptly and where a patentee delays for an unreasonable period, the patentee has the onus of showing that it delayed on reasonable grounds, such as a belief, on reasonable grounds, that an amendment was not necessary. • Unreasonable delay is a circumstance likely to lead to refusal of the amendment. • In assessing delay, the time when the patentee was unaware and reasonably did not know of the need for amendment is not taken into account. The relevant delay is from when the patentee knows of the likely invalidity, or has its attention drawn to a defect in the patent, or is advised to strengthen the patent by amendment. That is, amendment will not be permitted in cases where a patentee knows or ought to know that amendment should be sought and fails to do so for a substantial period of time. Thus the reasonableness of the conduct of the patentee is a relevant consideration when assessing delay. • Mere delay is not, of itself, sufficient to refuse to exercise the discretion to amend. The fact of delay is, however, relevant to whether the respondent or the general public have suffered detriment. • If a patentee seeks to take unfair advantage of the unamended patent, knowing that it requires amendment, then refusal of the amendment is likely. • The proportionality of the asserted culpability of the patentee as compared with the effect of loss of protection for the invention should be considered. These principles have been applied to amendments generally and operate as factors relevant to the exercise of the discretion to grant or refuse amendments. There may be other factors that are relevant in a particular case. We would add that the nature of the amendment and the ground of invalidity sought to be overcome by it are important matters to be taken into consideration when exercising the discretion. 1349 Further, in an earlier decision between the same parties but concerning a different patent, namely, Les Laboratoires Servier v Apotex Pty Ltd (2010) 273 ALR 630, Kenny and Stone JJ (at [92]) observed that it was not necessary for the patentee to know that the unamended claims were invalid for delay to be a relevant factor in the exercise of the discretion. It was enough that the patentee knew of significant invalidity risks yet delayed in seeking amendment. 1350 Further, a failure by the patentee to provide a full and frank disclosure of the reasons for seeking amendment is also a relevant factor in the exercise of the discretion. Further, where the patentee fails to voluntarily disclose an aspect of the reasons for seeking amendment until compelled to do so, that is also a relevant factor. Further, whilst obfuscation in the patentee's explanation "may have been attributable in part to a desire to avoid waiver of client legal privilege, that possibility does not affect the fact that it was open to the primary judge to conclude that [the patentee] failed properly to disclose its reasons …" ([83]). Moreover, even if it is not possible for the patentee to disclose relevant facts without waiving privilege, that does not "transform [the patentee's] obligation into something less than full and frank disclosure" (at [83]). 1351 In Novartis AG v Bausch & Lomb (Australia) Pty Ltd (2004) 62 IPR 71 Merkel J, after allowing the deletion and consolidation of certain dependent claims, considered whether to allow an amendment to the original form of claim 1 to remove a typographical error and to add a limitation to make the claim conform with data that indicated the limits at which the invention would work dealing with ion permeability values. The invention that his Honour was concerned with was contact lenses involving a discovery concerning the correlation between ion permeability and "on eye" movement. There were two sets of values involved, one calculated by the ionoton measurement and the other calculated by the ionoflux measurement. The amendments were not disallowable under s 102. Accordingly his Honour considered the exercise of discretion. His Honour observed that the courts had identified a distinction between validating amendments that cure otherwise invalid claims (in substance the case before me) and other amendments such as deletion amendments involving deleting invalid claims. At [66] his Honour said by reference to this distinction that: … As explained above, the issue of whether the amendments are validating arguments can be relevant to the amendment application. The issue is not relevant because any higher standard of proof or higher standard of conduct is required to be established in respect of such amendments. Rather, the relevance relates to whether the more lenient approach that might be applied to deleting amendments, or amendments that merely seek to correct errors or mistakes or remove ambiguities might be applicable. The reason for the leniency was explained by Pearson LJ in Van der Lely at 74-5 where his Lordship observed that a court is prima facie disposed to the deletion of invalid claims because if such claims were to remain in the patent they would constitute a potential "nuisance to industry". A similar observation can be made in respect of the mere correction of errors or mistakes which are not sought to cure any actual or potential invalidity. (Original emphasis.) 1352 His Honour concluded that the patentee had not made a full and accurate disclosure of all relevant matters "as it had not candidly disclosed the 'whole story of how it was that amendment had come to be sought'" (at [130]). 1353 His Honour then dealt with the question of delay. His Honour pointed out that amendment may be denied where the delay has caused detriment to a particular party or the general public. Moreover, where a lengthy delay has occurred, a reasonable explanation is required even if no public detriment is apparent (at [135]). In the case before him his Honour found that the patentee had been made aware of substantive errors in the claims six years before amendment was sought, but concluded that no proper explanation was given of the consideration given to the errors and why it was decided that no amendment was necessary. 1354 In rejecting the amendments, his Honour observed at [161] to [162]: The factors that militate against the granting of Novartis' application to amend can be summarised as follows: (i) the history of the patent's drafting indicates that the ion permeability values contained in it were chosen not as a matter of scientific judgment but, rather, as part of a policy of claiming as broadly as possible, even if this meant overstating the patent's claims without having reasonable grounds to do so; (ii) when problems with the ion permeability values were revealed, no steps were taken to correct those values by the amendment of the patent until more than six years after the patentees were aware or ought to have been aware of the problems, and no reasonable or satisfactory explanation for that delay has been provided; (iii) notwithstanding the problems concerning the ion permeability values, including the overstating of those values, there is no evidence that Novartis considered, or consulted its Australian legal advisers about, whether the patent should be amended until after the commencement of this proceeding and until after Bausch & Lomb had raised the issue of invalidity by reason of those ion permeability values; (iv) the patentees have not made a full and candid disclosure to the court of all the circumstances relevant to the amendment application. In summary, the present case is one in which the patentees knew or ought to have known that the substantive amendments they now seek to make should have been sought long ago, but have failed to provide a reasonable or satisfactory explanation for their delay, which can fairly be characterised as culpable delay. Further, the errors and other matters now sought to be corrected came about as part of a policy of overstating claims without having reasonable grounds for doing so. 1355 Further, under s 105(1), the Court may reject an amendment where the patentee seeks to take advantage of patent claims that it knows or ought to know should be amended. 1356 But on the question of knowledge of risk of potential difficulties, the prosecution of patent applications is jurisdiction specific given the different laws and procedures that apply (Neurim Pharmaceuticals (1991) Ltd v Generic Partners Pty Ltd [2018] FCA 1082 at [46] to [48] and [52] per Nicholas J and Bayer Pharma Aktiengesellschaft v Generic Health Pty Ltd (2012) 99 IPR 59 at [210] and [213] per Yates J). Now it may be problematic to glean too much from the patent applicants' overseas experience to determine whether as an exercise of discretion I should refuse the amendment application. Of course a patent applicant's knowledge of risk that is relevant to an assessment of the amendment application may be informed by its overseas experiences. But the relevant lens for the inquiry is knowledge of risk under Australian law, not foreign law. 1357 Let me make some other points. 1358 In Pfizer Overseas Pharmaceuticals v Eli Lilly & Co (2005) 225 ALR 416 (Pfizer) French and Lindgren JJ explained that (at [374]): …The requirement that an applicant disclose the best method known to the applicant of performing the invention safeguards against an applicant's holding back with a view to getting the benefit of the patent monopoly without conferring on the public the full consideration for the grant of that monopoly …. 1359 In Pfizer, French and Lindgren JJ noted that the date at which the best method known to the applicant is to be assessed is the date of filing (at [366] and [379]). But they did not accept the contention that a failure at the time of filing to disclose the best method known to the applicant at the time cannot in any circumstances be overcome by later amendment ([380] to [391]). 1360 As Pfizer makes clear, there are two questions of timing. 1361 First, as to the date at which the best method known to the applicant is to be identified, this is the date of filing of the complete specification. 1362 Second, as to the date by which that method must be disclosed in the complete specification in satisfaction of s 40(2)(a), this is also the date of filing of the complete specification. 1363 But in my view a failure so to disclose at that date can, theoretically, be cured by later amendment whether before or after grant. 1364 Further, Servier 2016 said that (at [239]): In Les Laboratoires Servier v Apotex Pty Ltd (2010) 273 ALR 630 at [60], Emmett J (Kenny and Stone JJ agreeing) observed that there is no limitation in s 105 of the Act on the purpose for which an amendment may be directed, noting that s 104 provides that a patentee might ask the Commissioner for leave to amend for any purpose, including, but not limited to, removing a lawful ground of objection to a request or specification. However, as Kenny and Stone JJ said at [76], guidelines have been developed in the authorities to assist in the exercise of the discretion. 1365 Servier 2016 also found that provided that amendments are allowable under s 102, amendments may be made to overcome invalidity, saying (at [240]): A number of matters may be accepted for the purposes of this appeal: • The discretion in s 105(1) to direct the amendment of a patent in relevant proceedings is unfettered. • Relevant proceedings include proceedings for revocation of the patent. • Section 102 provides for amendments that are not allowable. The proposed amendments do not fall into any such category and are thereby not precluded by reason of s 102. • In principle, amendments may be made to overcome invalidity. • Failure to comply with s 40(2) is a ground of revocation for which a patent may be revoked.

(b) Some relevant background 1366 Let me set out some relevant background. 1367 Between late 2005 and July 2006, BlueScope undertook a project investigating an improved form of galvalume. By the end of that project, BlueScope decided that the most attractive option for a differentiated product was based on an Al-Zn-Mg coating, because of its improved corrosion resistance. But during the project BlueScope had identified the problem of mottle. This was the result of the different physical characteristics of the Al-Zn-Mg coating as it transformed from a molten to solid state during the hot dipping process. 1368 Between August 2006 and 2013, BlueScope undertook the project which resulted in the claimed inventions, which was described as Project Edge. 1369 By February 2008, based on samples from an August 2007 line trial which were tested by the inventors, one of the inventors, Mr Renshaw, appreciated that the mottle defect was associated with the new Al-Zn-Mg coating's increased sensitivity to thickness variation. Apparently Mr Renshaw's observations were consistent with earlier work undertaken by the inventors. 1370 Dr Williams and Dr Liu had previously found that mottling corresponded with areas of high coating mass, where the overlay thickness was greater than 30 microns. They had hypothesised that Mg2Si nucleates first at the alloy layer, then at the free surface, but not in the middle. Dr Williams and Dr Liu had also hypothesised that Mg alters the viscosity of the molten alloy, which leads to thicker coatings. 1371 Mr Renshaw and Dr Williams had undertaken work on samples which had shown a strong correlation between mottle and high coating thickness on individual samples, and which had indicated that unstable coating weight was a contributing factor to mottle. Mr Renshaw concluded that restricting coating thickness variation to less than 40% over 5 mm increments would substantially eliminate mottle. But in evidence before me his conclusions seemed to be problematic in some respects as exemplified by the following discussion: MR RYAN: Thanks. And just to be clear - what you did at 320 was - you took four measurements at position 320, and you took an average of them? MR RENSHAW: That's - it's actually five measurements, but - yes. MR RYAN: Five measurements; thank you? MR RENSHAW: Yes. MR RYAN: And an average of them. And position - and that was over a distance of five millimetres? MR RENSHAW: Yes; those spots - so just to explain what the measurement is - the device is a probe about one millimetre in diameter. So - yes; you would measure five - that location five times with that probe. MR RYAN: Yes? MR RENSHAW: And those locations were five millimetres apart. MR RYAN: Okay. So the position 320 is perhaps better described as location 320, which is five millimetres long? MR RENSHAW: No. I wouldn't say the actual location is five millimetres; it's a one-millimetre spot that is five millimetres away from another one-millimetre spot. MR RYAN: Yes. Okay. So is the first spot - - - HIS HONOUR: Can you just draw that on the diagram? MR RENSHAW: Certainly. HIS HONOUR: So you got five measurements at 320 and five measurements at 325; so can you show us on a diagram? MR RENSHAW: Yes. Certainly. HIS HONOUR: Thanks? MR RENSHAW: So if we have something like that in that region - there would be five measurements in this region here, which is about one millimetre in diameter, and five measurements - repeated measurements on the same spot. HIS HONOUR: Repeated measurements on the one millimetre? MR RENSHAW: Yes. That's correct. Yes. HIS HONOUR: Well, that's - - -? MR RENSHAW: And the centres of those are five millimetres apart. HIS HONOUR: Yes. That's fine. Think that's a bit clearer, Mr Ryan. MR RYAN: Yes. Thank you. HIS HONOUR: You were thinking of one millimetre in a linear sequence, but it seems to be five measurements of that same one-millimetre spot; is that right? MR RYAN: Yes. MR RENSHAW: Yes. So the probe is like that. HIS HONOUR: Yes. MR RENSHAW: So it measures an average of that millimetre. HIS HONOUR: Yes. Thank you. MR RYAN: Thank you. We, probably, should take a picture of that. The court photographer, Mr Swinn, will do that. And, Mr Renshaw, in every other area in WAR8 where there is mottle - if one takes the average figure that you've identified and compared it with the one next-door - so to speak - the variation is far less than 40 - - -? MR RENSHAW: In many cases it is. In some cases it gets up to about 30 per cent. MR RYAN: That would be the max; wouldn't it? MR RENSHAW: Without having done all of them in front of me, I can't say what the maximum would be, but there are a few others that are around 30 per cent. MR RYAN: In most cases the variation is in single figures; isn't it? MR RENSHAW: In many cases it is; yes. MR RYAN: Yes. Now, doesn't that suggest that the cause of the mottle on these August 2007 samples was the high cooling rate at that trial, rather than the thickness variation? MR RENSHAW: I don't think it's that simple; it's a combination of the two. For example, if you look at many of the mottled areas - they are ..... areas of thicker coating. That thicker coating can arise from long-range variation and short-range variation. So for example - the - some of the points on the other surface - so if we go to page 94 - there are a batch of points around the 555 through to 575, where the coating is 27.6 to 3.4 micrometres thick, and that - those points were consistently mottled. So really it's the - they are the sort of the thickest areas of the coating, and that's where we expect to see mottle. So it's the combination of the two. HIS HONOUR: Is that right - but if I look down that diagram - there's no consistency necessarily between thickness and mottling; is there. All right. So if you look down that column - sometimes you've got no mottling. 27.1 - so that's thicker; that's at the 550, whereas if you've got - you do have mottling at 26.6, which is at 515; so do you follow that, that sometimes you've got a - - -? MR RENSHAW: Yes, I do follow that. The answer I had for that - - - HIS HONOUR: It's less thick, and it's showing mottling; so there's no consistent pattern there necessarily between - - -? MR RENSHAW: There's not a - it's not a sharply defined pattern. HIS HONOUR: No? MR RENSHAW: I will put it that way. HIS HONOUR: Yes? MR RENSHAW: If you go back to page 83 and 84 of the confidential evidence, which is the tech note that Joe - Dr Williams and I wrote, you will see that there's a distribution for thicknesses for mottled and non-mottled regions, and those distributions overlap, and that's what we're seeing in a point-by-point measurement. HIS HONOUR: Yes? MR RENSHAW: In the case of these graphs on 83 and 84 - those points weren't five millimetres apart; they were just randomly selected from mottled and non-mottled regions. So what you see there is that - what I've done differently to this work with marking out is try to understand the spatial variation, not just the variation in thickness as a statistical whole. So you would expect, considering what we've seen in pages 83 and 84, the overlap between the thickness of mottled and non-mottled regions - you would expect to see some inconsistency, but on average the mottled regions are thicker than the non-mottled regions. MR RYAN: Mr - - - HIS HONOUR: And that's - sorry. MR RYAN: Pardon me, your Honour. HIS HONOUR: But the other potential variable is the cooling rate, which of course is not shown on these figures? MR RENSHAW: Indeed it is [not]. Yes; that's correct. HIS HONOUR: So how do we know that, if we factored out any change in the cooling rate, you would show this pattern of more mottling, the thicker - - -? MR RENSHAW: That's right. The actual - the impact of a cooling rate would be to shift these curves right and left. HIS HONOUR: Right? MR RENSHAW: Right? So a higher cooling rate would shift the curves to the left; so you would have mottle in - start to see mottle in thinner regions. The lower cooling rates would shift the curves to the right. HIS HONOUR: Yes? MR RENSHAW: And you would see less mottle in the thicker - in a given thickness region. HIS HONOUR: Thank you. MR RYAN: And to perhaps put it another way, Mr Renshaw - as your thickness of your coating increases, you would wish your cooling rate to come down? MR RENSHAW: Indeed; yes. That's correct. MR RYAN: And does it follow, that in that August 2007 trial, where you had cooling rates that we saw on that graph going up above 65 degrees Celsius - that if those cooling rates hadn't been so high, if they had come down to, say, 30, like you used in the 2009 trials, we wouldn't have seen mottle on those samples at all? MR RENSHAW: That's a possibility; yes. That's right. HIS HONOUR: In fact, from recollection - that graph first started to show mottling at around the - was it 65-degrees-per-second cooling rate? I think - - -? MR RENSHAW: Yes. That's right. HIS HONOUR: Yes. Yes. MR RYAN: Yes. We can go back to it, but that's correct, your Honour. HIS HONOUR: Yes. That's right; yes. 1372 BlueScope had not previously controlled short range coating thickness variation through the use of air knives and a stabiliser. Apparently, this was not something that was necessary for galvalume. Apparently, another visual defect, which did not involve the presence of Mg2Si at the surface, was controlled in galvalume by controlling the composition of the bath. 1373 Now it was evident to Mr Renshaw that standard air jet settings used for the production of galvalume were unsuitable for the production of the new Al-Zn-Mg coating. 1374 Apparently Mr Renshaw knew that short range coating thickness variations could be controlled by adjusting the jet stripping apparatus by reducing the height of the wiping gas outlets of the jet stripping apparatus above the coating bath so that these outlets were closer to the coating bath, adjusting the jet stripping apparatus by reducing the distance between the wiping gas outlets and the coated strip whilst reducing the pressure of the wiping gas and using a stabiliser to control the lateral movement of the strip between the jets. 1375 Mr Renshaw explained that for the production of galvalume, the distance between jets was typically 12 to 14 mm and the height of the jets was typically 200 to 350 mm. But to reduce short range coating thickness variation, it was necessary to reduce the turbulence of the jets by moving the jets closer. But there was a limit to how close the jets could be positioned in relation to the strip, because it was necessary to ensure that the strip did not touch the jet. 1376 Mr Renshaw did not know what the short range coating thickness variation of galvalume coatings were as it had not been measured, although he suspected that the problem was worse on Al-Zn-Mg-Si coatings. There was some short range variation on galvalume coatings, but mottle on galvalume coatings was not the same problem. For the Al-Sn-Mg-Si alloy, the long range variation was the same as for galvalume, but the short range coating thickness variation gave rise to mottle. 1377 Apparently Mr Renshaw appreciated that the lateral movement of the strip imposed a practical limit on the ability to reduce the distance between jets, but considered that this lateral movement could be reduced by a stabiliser. A stabiliser, for example, an electromagnetic strip stabiliser or an air flotation stabiliser, stabilises the coated strip between the jets of the jet stripping apparatus so that the distance between the jet stripping apparatus and the coated strip remains constant. 1378 Now once the link between short range coating thickness variation and mottle had been drawn, the inventors knew that it was necessary to move the jets closer together and closer to the strip to minimise short range coating thickness variation. But to move the jets closer and lower, it was also necessary to stabilise the strip so that the strip would not touch the jets. 1379 It was apparent to BlueScope from the middle of 2008 that it might be necessary to optimise the jet stripping conditions, including by introducing stabilisers. But at this time this was a low priority for BlueScope until a commercially viable coated steel product could be developed. Following the 2007 trial, and up to the end of 2009, further line trials were put on hold. 1380 On 15 February 2008, Mr Munt circulated the first draft of the provisional application. 1381 On 19 February 2008, one of the inventors, Dr Liu, proposed the language "special operational measures" in a second draft of a provisional application, although the inventors did not discuss the expression at that stage. The first draft had been created by BlueScope's patent attorneys. The proposed language used was: However, the applicant found that, short range coating thickness variation could be very high, and special operational measures have to be applied to kee[p] it under control… 1382 Mr Munt amended the passage to read: However, the applicant found that, short range coating thickness variation could be very high, and special operational measures had to be applied to kee[p] it under control… 1383 Mr Munt said that he made this amendment for reasons of grammatical consistency, but without intending to make substantive changes. Mr Munt made the change as the other references to the findings of the inventors in the relevant passage used "had" and not "have". At the time Mr Munt made this amendment, he had no knowledge of whether special operational measures had been used. 1384 Further, in late February 2008, BlueScope's Mr Fellows and one of the inventors, Dr Liu, apparently did not know the precise mechanisms to introduce to control short range coating thickness variations. Apparently they advised Mr Munt of this, according to Mr Munt's file note in evidence dated 29 February 2008. 1385 In March 2008, one of the inventors, Mr Renshaw reviewed the most recent draft specification and provided feedback at the invitation of the other inventors. Mr Renshaw thought the expression "special operational measures" was sufficiently clear, and did not change the expression. Further, he may not have noticed the change made by Mr Munt from "have" to "had". The expression was retained in later drafts without further discussion. The provisional application was filed on 13 March 2008 with the word "had". 1386 On 13 March 2009 the PCT application was filed and was closely based on the provisional application. In this respect BlueScope did not provide any additional data to Mr Munt. The expression "special operational measures" was retained. For completeness I note that on 25 June 2010 it was requested that the PCT application proceed as an application for an Australian standard patent. On 5 July 2010 notification was given by IP Australia that the PCT application had been designated as No. 2009225257. 1387 A line trial was conducted in March 2009. The March 2009 trial was conducted at speeds and cooling rates that were not suitable for commercial production. The Project Edge team did not expect that mottle would result and none was observed. As a result, no measures were implemented to address mottle, including arrangements to reduce short range coating thickness variations. There was no alteration to the arrangement of the jets or the introduction of the stabiliser. Before that time, BlueScope typically situated the jet approximately 350 mm above the coating bath and 14 mm from the coated steel strip and applied a pressure of 7 kPa. 1388 In November 2009, a further line trial was conducted on MCL4. In the November 2009 trial a temporary air jet configuration was tested in which the air jets were moved closer to the strip and an air floatation stabiliser device was used. In December 2009, BlueScope produced a manufacturing update which said that the best product had been produced when a prototype air flotation stabiliser allowed jet stripping at a particular jet to jet distance. This work continued until February 2012; apparently BlueScope first used a commercial air flotation stabiliser in 2011. Further adjustments continued to be made later in 2012 and in 2013 prior to the commercial launch of BlueScope's product. 1389 In 2013 a final line trial was conducted on MCL4 to confirm the production capability of BlueScope's coated steel product. This included final modifications to the upleg cooler and modified jet stripping conditions. Following the successful completion of the 2013 line trial, BlueScope launched its coated steel product.

(c) Prosecution in Australia 1390 On 7 December 2012, during the prosecution of the application, the Australian Patent Office (APO) issued its first examination report. The report raised an objection to the application on the basis that the claimed invention lacked novelty and an inventive step and that no notice of entitlement had been filed. The first examination report did not raise any issue concerning the expression "special operational measures". 1391 On 3 September 2014, Mr Munt sent a response to the first examination report enclosing a first statement of proposed amendments, marked up specification pages and a notice of entitlement. It stated the following: We request leave to amend the complete specification in accordance with the First Statement of Proposed Amendments. We request the withdrawal of the postponement of acceptance of this application. We are proposing to amend the original claims to base the claims on original independent method claim 22 with amendments to that claim. Amended claim 1 defines the invention as follows: A hot-dip coating method for forming a coating of a corrosion-resistant Al-Zn-Si-Mg alloy on a steel strip comprising passing the steel strip through a hot dip coating bath that contains Al, Zn, Si, and Mg and optionally other elements and forming an alloy coating on the strip with a variation in thickness of the coating of no more than 40% in any given 5 mm diameter section so that the distribution of Mg2Si particles in the coating microstructure is such that there is only a small proportion of Mg2Si particles or substantially no Mg2Si particles in the surface of the coating. The invention is concerned with Al-Zn-Si-Mg alloy coatings on steel strip and, in particular with a surface defect called "mottling". Page 3, lines 20-30 of the subject specification describe that a problem of known Al-Zn-Si-Mg alloy coatings is a tendency to form the mottling surface defect. The present invention is concerned with minimising the occurrence of the Mg2Si mottling surface defect. 1392 The response further noted that the applicant had carried out line trials, which were described as "an important step in the development of an invention to a commercial stage". It also referred to one of the two factors affecting the coating microstructure in the trials as coating thickness variation. 1393 On 4 September 2014, the APO issued its second examination report. In that examination report, the APO raised an objection to the application on the grounds that claims 1 to 15 lacked full description, and did not provide the best method of performing the invention known to the applicant. At item 3, "Section 40 (Fair Basis, Full Description, Clarity, Lack of Unity", it noted the following passage of the specification: … However, the applicant found that short range coating thickness variations could be very high, and special operational measures had to be applied to keep the variations under control. It was not uncommon in the experimental work for the coating thickness to change by a factor of two or more over a distance as short as 5mm, even when the product perfectly met the minimum coating mass requirements as defined in relevant national standards. This short range coating thickness variation had a pronounced impact on the Mg2Si particles in the surface of the coatings. … 1394 The APO then said: Reviewing the specification as a whole, I can find no disclosure of what those special conditions are so as to provide the defined thickness variation. Do the special operational measures relate to the pot? to use of a gas knife? or to another element of the process? Given the measures are considered "special" and, according to the applicant's recent response involved extensive research work and line trials, I am not presently satisfied they would be immediately recognisable to the person skilled in the art as part of the common general knowledge or as matter uncoverable by routine trial and error. As such I am not satisfied the subject matter claimed is enabled. Further, I am not satisfied the subject matter claimed is provided with a best method of performance. Referring to 2.11.3.17 of the IP Australia Patent Examiners' Manual (emphasis added): The specification, in addition to fully describing the invention, must include 'the best method of performing' the invention. In American Cyanamid Company v Ethicon Limited (1979) RPC 215 at page 269, it was stated: 'The Act is intending to protect the public against a patentee who deliberately keeps to himself something novel and not previously published which he knows of or has found out gives the best results, with a view to getting the benefit of a monopoly without giving to the public the corresponding consideration of knowledge of the best method of performing the invention.' Consequently, even if a manner of performing an invention is self-evident, applicants are nevertheless required to set out the best method of performing the invention known to them." (Original emphasis.) 1395 On 4 September 2014, Mr Munt spoke with the examiner regarding the second examination report. 1396 On 5 September 2014, Mr Munt responded to the second examination report by explaining that: With regard to item 3 of the second patent examination report, we submit that a skilled person in the field of forming metal alloy coatings on steel strip, on reading the specification and finding that the invention is concerned with minimising coating thickness variations of Al-Zn-Si-Mg alloy coatings on steel strip to control the distribution characteristics of a Mg2Si phase in the coating so that the surface has only a small proportion of Mg2Si particles or is at least substantially free of Mg2Si particles, could determine by non-inventive trial and experimentation the required operational measures to achieve this outcome on a metal alloy coating line. The specification discusses the impact of such short range thickness variations, i.e. variations "of no more than 40% in any given 5 mm diameter section" as defined in claim 1 on a metal alloy coating line. In particular, as noted by us in our response to the first patent examination report and by the examiner in the second patent examination report, the impact of such short range thickness variations is described in the following passage on page 13, lines 1-11 of the specification: "However, the applicant found that short range coating thickness variations could be very high, and special operational measures had to be applied to keep the variations under control. It was not uncommon in the experimental work for the coating thickness to change by a factor of two or more over a distance as short as 5 mm, even when the product perfectly met the minimum coating mass requirements as defined in relevant national standards. This short range coating thickness variation had a pronounced impact on the Mg2Si particles in the surface of coatings." The skilled person in the field is a person who has experience in operating metal alloy coating lines and therefore understands the parameters that can be varied to control the line and, in particular, would understand the "special operational measures" mentioned in the above-quoted passage in the specification that could be applied to achieve the necessary control. The term "special" is intended to be understood in this context that they are not the usual measures employed to control a metal alloy coating line. As described on page 12, lines 22-36 of the specification, in "a production situation, the long range thickness variation is normally regulated to meet the minimum coating mass requirements as defined in relevant national standards" and "as far as the applicant is aware, there is no regulation for short range thickness variation, as long as the minimum coating mass requirements as defined in relevant national standards are met." By way of example, the skilled person would understand that control of the gas stripping equipment that controls coating thickness is one of a number of measures that have an impact on controlling short range thickness variations of coatings. One particular control measure for the skilled person is to adjust the height of the stripping knife above the coating bath. 1397 Apparently, Mr Munt's response was based on a discussion with Mr Renshaw. Mr Munt explained that he understood that the measures taken were "special" because the positions or settings to be selected were not those usually selected for conventional Al-Zn-Si coatings. 1398 Mr Munt considered that his response dealt with the objections raised by the APO. Further, apparently he made a judgment call that it was not necessary to amend the specification to state the special operational measures required, and that he made that judgment call without discussing the possibility of amendment with BlueScope. 1399 The APO accepted the application on 8 September 2014 and granted the 257 Patent on 8 January 2015. 1400 On 5 October 2016 BlueScope was alerted to the prospect that it might be necessary to amend the 257 Patent when BlueScope's counsel and solicitors raised the issue at a meeting on that day. BlueScope was advised that it may be desirable to amend the specification of the 257 Patent to include details of the "special operational measures" known to BlueScope so as to guard against the risk that the specification may not adequately disclose the best method known to BlueScope at the filing date of performing the invention. 1401 On 23 November 2016, King & Wood Mallesons informed Mr Mackenzie of BlueScope that in order to determine whether an amendment should be sought and, if so, the appropriate form of any such amendment, consideration would need to be given to what BlueScope understood to be the best method for controlling short range thickness variations at the date on which the patent was filed. This would involve collecting and reviewing documents and interviewing those involved with the technology to identify the state of BlueScope's knowledge. In December 2016, Mr Renshaw provided King & Wood Mallesons with documents relating to Project Edge. 1402 On 13 December 2016 the present proceedings were commenced and allocated to another docket judge. The case was transferred to my docket just over a year later on 22 December 2017. 1403 On 24 January 2017, King &Wood Mallesons advised Mr Mackenzie that BlueScope would need to apply to amend the 257 Patent. But apparently, until King & Wood Mallesons had completed its investigations, BlueScope was not in a position to form a concluded view as to what form the proposed amendments should take. 1404 On 25 January 2017, BlueScope gave instructions to seek consent orders in this Court making provision for the filing of an amendment application by 13 April 2017. 1405 On 21 February 2017, Mr Renshaw met with King & Wood Mallesons and explained, consistent with his understanding, the ways in which short range coating thickness variations could be controlled. He explained that special operational measures was a reference to: (a) reducing the height of the stripping jets; (b) moving the stripping jets closer to the strip whilst reducing the pressure; and (c) stabilising the coated strip. 1406 At the end of March 2017, King & Wood Mallesons provided a proposed form of amendment to BlueScope. 1407 On 3 April 2017, BlueScope instructed King & Wood Mallesons to notify the Commissioner of Patents and make an application to this Court to amend the 257 Patent. On 13 April 2017 the application to amend was filed in this Court.

(d) Prosecution abroad of corresponding patent applications 1408 Let me say something separately about the prosecution of corresponding patent applications in each relevant foreign jurisdiction.

Chinese patent application 1409 In December 2012, the Chinese Patent Office objected to BlueScope's application for a corresponding Chinese patent. On 11 December 2012, Mr Munt received an English summary of the Office Action from his Chinese associates, Beijing Sunhope Intellectual Property Ltd. The basis of the objection was that the Chinese specification did not explain how to control coating thickness variation. Under section II "Summary of the OA3" (p 1), it stated: 1. Claim 1 is rejected under Rule 20 of the Implementing Regulations of the Chinese Patent Law as lacking essential technical features for solving the aimed technical problem. In order to achieve that no more than 10 wt% of Mg2Si particles exist in the surface of the coating, the following technical mean was used: the coating thickness variation is no more than 40% in any given 5 mm diameter section of the coating. In fact, this technical means is just a "result", the technical means and technological parameters used for controlling the coating thickness variation are the indispensable technical features to arrive at this "result", that is to say, claim 1 lacks the essential technical features to achieve the objectives of the present invention. 1410 On 30 January 2013 BlueScope was notified of this objection when Mr Munt sent an email attaching the summary to Mr Gennaro Simonetta, a patent attorney seconded to BlueScope, one paragraph of which stated: I am surprised to receive the office action since I had expected that the response to the previous office action would place the application in order for grant. In the circumstances, and given that the objections relate to the scope and clarity of the claims rather than patentability issues, I have asked my associate to provide comments in relation to the objections. 1411 On 31 January 2013, Mr Munt received a further email from his Chinese associates attaching the pending claims and their comments on the Office Action. In relation to the objection, they commented: 1. As for claim 1 lacking essential technical features for solving the aimed technical problem After studying the Description of the present invention, we have found the following contents in Lines 18-22 of Page 2 in the PCT International Publication: After leaving the coating bath the metal alloy coated strip passes through a coating thickness control station, such as a gas knife or gas wiping station, at which its coated surfaces are subjected to jets of wiping gas to control the thickness of the coating. Thus, based on the above records, the applicant can attempt to argue with the Examiner from the following points of view: just as disclosed in the Description of the present invention, the technical means and technological parameters used for controlling the coating thickness variation are routine means (such as gas knife or gas wiping station) which is well known by the skilled in the art, in this case, it is not necessary to incorporate the specific means used for controlling the coating thickness variation into claim 1. However, we have not found the corresponding records, that the reasons why no more than 10 wt.% of Mg2Si particles or no Mg2Si particles in the surface of the coating can be achieved by controlling the coating thickness variation no more than 40% in any given 5 mm diameter section of the coating, in the Description of the present invention. If possible, please kindly provide us with some detailed technical explanation in this regard. Moreover, based on the records of Pages 13-14 in the Description of the present invention, we consider that both of controlling the cooling rate and the uniformness of coating thickness are possible to affect the distribution of Mg2Si particles in the coatings. Please confirm whether the cooling rate controlling is also an essential technical feature for solving the aimed technical problem. 1412 Mr Munt's Chinese associates asked for an explanation of the special operational measures. 1413 On 2 April 2013 he sent an email asking his Chinese associates to write to the Chinese Patent Office and to draw their attention to parts of the specification, including the passage about special operational measures. Apparently on 7 April 2013, the Chinese associates filed a response with the Chinese patent office. 1414 The objection appears to have been overcome and the patent was granted on 4 September 2013.

South Korean patent application 1415 On 20 June 2014, the South Korean Intellectual Patent Office objected to BlueScope's South Korean 576 application for a corresponding South Korean patent issuing a Notification of the Reasons for Rejection. The basis of the objection was that the specification did not explain how to control coating thickness variation. Section 4 stated: 4. Description of the Specification of this application is considered defective in view of the grounds set forth below, thereby failing to meet the requirements under Article 42, Paragraph 3 of the previous version of the Korean Patent Law (before amended on 24 May 2011 by Act No. 10716). The present invention of claims 22-26 is directed to a hot-dip coating method for forming an alloy coating with minimal variation in the thickness of the coating. However, the Description of the Specification (paragraphs [0097-0101]) does not disclose how the alloy coating with minimal variation in the thickness of the coating is formed and what kind of conditions of the hot-dip coating method should be controlled to obtain such results. Further, it is considered to be difficult for one skilled in the art to find suitable conditions of the hot-dip coating method through the repetition of experiments, even if they consider the disclosure of the specification and common knowledge in the field. Therefore, for the reasons given above, the specification of the present application is not deemed clear enough to allow one skilled in the art to implement the invention. 1416 On 29 July 2014, Mr Munt was notified of this objection by his South Korean associates, KJ Lee Patent & Trademark Law Firm. 1417 On 20 August 2014, Mr Munt notified BlueScope of the South Korean objection. 1418 Now Mr Munt was asked in cross-examination whether he could have responded to the complaint by fleshing out what special operational measures meant. But he explained that this was one of numerous objections raised, and that if he accepted every objection on face value, he would not have any patents. It is apparent that Mr Munt did not perceive the objection as having particular force. He gave the following evidence: MR RYAN: Well, one answer to that - to that complaint would be to flesh out what might be meant by the special operational methods, wouldn't it? MR MUNT: Not the only response. I mean, your Honour, if I just may make the point here that this is one objection amongst numerous objections raised by the Korean patent office. If I was to accept on face value every objection raised by every patent office, we wouldn't have any patents. The patent offices are charged to raise objections and they do, and there are numerous objections here. MR RYAN: And, yes, Mr Munt, you in fact responded to this objection, didn't you, in the same - essentially the same terms as you responded to the corresponding objection which was made by the Australian patent office, which we saw - - -? MR MUNT: Yes. MR RYAN: - - - a little while ago? MR MUNT: Yes. MR RYAN: So if you go over to page 550 - - -? MR MUNT: Yes. MR RYAN: - - - the second-last paragraph: A skilled person on reading would have no difficulty - etcetera. The next person: The skilled person is a person who has experience - etcetera, and your response to the Korean patent office is in virtually the same terms as you responded to the Australian patent office; correct? MR MUNT: Correct. MR RYAN: Correct? MR MUNT: Yes. MR RYAN: Well, didn't the penny drop that there was a problem with the expression "special operational measures" that ought to be fixed by amendment of the specification so as to flesh them out for people to read and try and understand? MR MUNT: No, the objection raised by the Korean patent office doesn't refer to special operational measures as a term that's not understood. The objection was responded to and the objection was overcome. So, again, it's one of a number of objections. It was considered. Instructions were provided. A response was lodged and the objection was overcome. As I said - as I said to you, because an objection is raised does not mean it is correct, and the laws of different countries are - are quite wide and varied. Sure, there's novelty inventive step basic laws but the practices of the patent offices are quite different. MR RYAN: Sure. You had two choices here, didn't you? You could argue the toss with the examiner and try and maintain the form of your specification, or you could propose an amendment to include a description of the special operational measures, couldn't you? MR MUNT: I had choices and I chose the submission route first. That's the route that we followed in Australia. It was successful. We took that as the first option, and it was successful in Korea. 1419 On 20 November 2014, Mr Munt gave his South Korean associates instructions to respond in essentially the same terms as he had responded to the APO. He asked his South Korean associates to respond using, inter-alia, the following comments as a basis: The skilled person, on reading the specification as a whole, would have no difficulty putting the invention into effect. Specifically, the skilled person could determine by non-inventive trial and experimentation the required operational measures to achieve this outcome on a metal alloy coating line. The skilled person is a person who has experience in operating metal alloy coating lines and therefore understands the parameters that can be varied to control the line and, in particular, would understand the "special operational measures" mentioned in the page 14, line 27 in the specification that could be applied to achieve the necessary control. The term "special" is intended to be understood in this context that they are not the usual measures employed to control a metal alloy coating line. 1420 Although Mr Munt discussed his response with BlueScope, he did not raise the possibility of amendment with BlueScope. 1421 In December 2014, BlueScope's South Korean associates responded to the South Korean Intellectual Property Office. Although the examination remains subject to an appeal, the objection relating to this issue has apparently not been maintained.

Japanese 619 patent 1422 On 29 July 2016, BlueScope's corresponding Japanese 619 patent, which had been examined by the Japanese Patent Office and granted, was opposed by an individual. On 29 August 2016, Mr Munt was made aware of this by his associate firm in Japan, Aoyama & Partners. However, Mr Munt was not made aware of the nature of the objection until 3 October 2016. 1423 On 3 October 2016, Mr Munt received a translation of a notice of reasons for revocation dated 29 September 2016 from his associate firm in Japan. The covering letter from Aoyama & Partners noted that: The examiner rejects this patent on the grounds of lack of novelty based on D1, lack of inventive step based on D1, lack of enablement and lack of clarity of claims as the result of a panel of three Appeal Examiners. You can submit a response within 90 days from issuance of the Office Action. The response may include an argument and a request for correction including a claim amendment. 1424 The notice stated the grounds of revocation including: This patent should be revoked on the grounds as set forth below as the result of a panel of Appeal Examiners. If the Patentee has any opinion thereon, an argument response should be submitted with two copies within 90 days from the issuance of this Office Action. … 3-1. In the invention, the statement of the specification does not comply with the description requirements under Article 36, paragraph 4(1) of the Japanese Patent Law on the points mentioned below. (Lack of enablement) 1425 On 7 October 2016, Mr Munt received a further letter from Aoyama & Partners enclosing a translation of the opposition to grant of patent. The opposition noted that "special operational measures" were not described. The notice of reasons for revocation asserted lack of enablement. The opposition noted: Sum and substance of the ground Article 36(4)(i) of Patent Law It is recognized from the description of paragraph [0082] of the detailed description of the invention (specification) (page 14, lines 25 to 28) that special operational measures have to be applied to keep coating thickness variations under control, but the special operational measures are neither described nor suggested in the detailed description of the invention. Therefore, the detailed description of the invention is not described in a manner sufficiently clear and complete for the invention described in Claims to be carried out by a person with ordinary skill in the art. 1426 On 18 October 2016, Mr Munt received a further letter from Aoyama & Partners enclosing their comments on the notice of reasons for revocation and the opposition. The comments noted in relation to lack of enablement: We understand that the special operational measures include adjusting a variation in thickness of the coating in any given 5 mm diameter section of the coating to no more than 40%; and factors for reducing the variation include the cooling rate for coated strip exiting the coating bath, concentrations of Sr in the coating bath and the like, as described in pages 15 to 19, particularly page 18, line 10 to page 19, line 11 of the specification. … We would like to receive your technical comment thereon. 1427 On 22 December 2016, Mr Munt responded to Aoyama & Partners based on his response to the second examination report provided to the APO. His response included the following: 1. Enablement A skilled person in the field of forming metal alloy coatings on steel strip, on reading the specification and finding that the invention is concerned with minimising short term coating thickness variations of Al-Zn-Si-Mg alloy coatings on steel strip to control the distribution characteristics of a Mg2Si phase in the coating so that there is no more than 10 wt.% of the Mg2Si particles in the surface of the coating, could determine by non-inventive trial and experimentation the required operational measures to achieve this outcome on a metal alloy coating line. The specification discusses the impact of such short range thickness variations, i.e. variations "of no more than 40% in any given 5 mm diameter section" as defined in claim 1 on a metal alloy coating line. In particular, as noted above, the impact of such short range thickness variations is described in the following passage on page 13, lines 1-11 of the specification: "However, the applicant found that short range coating thickness variations could be very high, and special operational measures had to be applied to keep the variations under control. It was not uncommon in the experimental work for the coating thickness to change by a factor of two or more over a distance as short as 5 mm, even when the product perfectly met the minimum coating mass requirements as defined in relevant national standards. This short range coating thickness variation had a pronounced impact on the Mg2Si particles in the surface of coatings." The skilled person in the field is a person who has experience in operating metal alloy coating lines and therefore understands the parameters that can be varied to control the line and, in particular, would understand the "special operational measures" mentioned in the above-quoted passage in the specification that could be applied to achieve the necessary control. The term "special" is intended to be understood in this context that they are not the usual measures employed to control a metal alloy coating line. As described on page 12, lines 22-36 of the specification, in "a production situation, the long range thickness variation is normally regulated to meet the minimum coating mass requirements as defined in relevant national standards" and "as far is the applicant is aware, there is no regulation for short range thickness variation, as long as the minimum coating mass requirements as defined in relevant national standards are met." By way of example, the skilled person would understand that control of the gas stripping equipment that controls coating thickness is one of a number of measures that have an impact on controlling short range thickness variations of coatings. One particular control measure for the skilled person is to adjust the height of the stripping knife above the coating bath. In this context, it is relevant to note that the "conventional" metal coating method (and line) described on pages 2 and 3 of the specification is the conventional method (and line) used by most companies that produce metal alloy coatings on steel strip. The method (and the line) would be very familiar to skilled persons in metal coating technology in Japan and elsewhere. The skilled person would understand straight away what factors to consider when told that it is important to control short term thickness variations, i.e. "a variation in thickness of the coating of no more than 40% in any given 5 mm diameter section of the coating so that the distribution of Mg2Si particles in the coating" as defined in claim 1. 1428 The Japanese Patent Office pressed other objections, but not the ground of lack of enablement. 1429 In evidence before me Mr Munt explained that he did not consider there to be a need to consider the position in Australia based on the Japanese Patent Office action, because the position had been evaluated in Australia. Mr Munt discussed the Japanese Patent Office action with BlueScope, but he did not raise the possibility of amendment with BlueScope. 1430 Let me deal with one other matter concerning the Japanese position. 1431 On 21 June 2016 a Japanese divisional 551 application, which was a divisional of the Japanese 619 patent, was also the subject of an office action. One of the objections was lack of enablement on the basis that the specification did not explain how to control short range coating thickness variations. On 4 August 2016, Mr Munt sent details of this objection to BlueScope. On 21 December 2016, Mr Munt instructed BlueScope's Japanese attorney to respond. On the same day, BlueScope's Japanese attorneys responded to the Japanese Patent Office. The Japanese divisional application was refused on 6 June 2017, being after Mr Munt had made his affidavit in the present proceeding. Mr Munt was unable to recall why the application was refused.

US patent application 1432 Let me say something about the US application No 12/811,213, although little was said about this in Mr Munt's written evidence. 1433 The US Patent and Trademark Office had rejected certain claims of the application on the basis that they were anticipated by Kurosaki. 1434 On 16 February 2015, Mr Munt's US associate Michael Best & Friedrich LLP responded to the office action. The US associate's response was to submit that the key inventive step was the control of distribution of Mg2Si particles in the coating, and referred to the passage in the application on special operational measures. The US associate stated, inter-alia, the following: b. Patentability Remarks At page 7 of the Office action, the Examiner rejects claims 22 and 24-28 under 35 U.S.C. s 102(b) as allegedly being anticipated by U.S. Patent No. 6,635,359 to Kurosaki et al. ("Kurosaki"). At page 8 of the Office action, the Examiner rejects claims 22, 24-28 and 30-32 under 35 U.S.C. s 103(a) as allegedly being obvious over Kurosaki alone or with U.S. Patent No. 5,571,327 to Ookouchi et al. ("Ookouchi"). At page 11 of the Office action, the Examiner rejects claims 22, 24-28 and 30-32 under 35 U.S.C. s 103(a) as allegedly being obvious over Kurosaki in view of WO 2006/105593 ("WO 593"), JP 06-279889 ("JP 889), or in further view of JP 2001-316791 ("JP 791"). Applicant respectfully disagrees with the Examiner's arguments and traverses the rejections for at least the reasons that follow. Applicants submit that the key inventive concept of the subject invention is to control the distribution of Mg2Si particles in coatings by minimising short range coating thickness variations. Amended independent claims 22 and 32 include further method steps of the hot-dip coating method of the invention. In particular, the steps of "passing the coated steel strip from the coating bath through a coating thickness control station, and passing the coated steel strip through a cooling section and cooling the coated steel strip" provide context for the additional method step of amended claims 22 and 32 of "controlling the method to form an alloy coating on the strip with a variation in thickness of the coating …". More particularly, the amended independent claims now include an explicit control step to ensure the formation of the required short range coating thickness variations defined in the claim. Page 14, line 5 to page 15, line 13 of the subject specification describes that: The second important factor found by the applicant is the uniformness of coating thickness across the strip surface (emphasis added). The applicant found that the coating on the strip surface normally had thickness variations that are (a) long range (across the entire strip width, measured by the "weight-strip-weight" method on a 50mm diameter disc) and (b) short range (across every 25 mm length in the strip width direction, measured in the cross-section of the coating under a microscope with 500 magnification). In a production situation, the long range thickness variation is normally regulated to meet the minimum coating mass requirements as defined in relevant national standards. In a production situation, as far is the applicant is aware, there is no regulation for short range thickness variation, as long as the minimum coating mass requirements as defined in relevant national standards are met. However, the applicant found that short range coating thickness variations could be very high, and special operational measures had to be applied to keep the variations under control. It was not uncommon in the experimental work for the coating thickness to change by a factor of two or more over a distance as short as 5 mm, even when the product perfectly met the minimum coating mass requirements as defined in relevant national standards. This short range coating thickness variation had a pronounced impact on the Mg2Si particles in the surface of coatings. By way of example, the applicant found that for a AZ150 class coating even in the desirable cooling rate ranges as described above, if the short range coating thickness variation was greater than 40% above the nominal coating thickness within a distance of 5 mm across the strip surface, Mg2Si particles formed on the surface of the coating and thereby increased the risk of mottling. Therefore, under the experimental conditions tested, the short range coating thickness variation should be controlled to no greater than 40% above the nominal coating thickness within a distance of 5mm across the strip surface to avoid mottling. The above passage describes that "special operational measures had to be applied to keep the variations under control." In other words, the above passage describes the control step defined in amended claims 22 and 32. Applicants submit that the skilled person in the field is a person who has experience in operating metal alloy coating lines and therefore understands the parameters that can be varied to control the line and, in particular, would understand the "special operational measures" mentioned in the above-quoted passage in the specification that could be applied to achieve the necessary control. The term "special" is intended to be understood in this context that they are not the usual measures employed to control a metal alloy coating line. As described on page 14, lines 15-23 of the specification, in "a production situation, the long range thickness variation is normally regulated to meet the minimum coating mass requirements as defined in relevant national standards" and "as far is the applicant is aware, there is no regulation for short range thickness variation, as long as the minimum coating mass requirements as defined in relevant national standards are met." There is no disclosure in Kurosaki that contradicts this statement in the subject specification… 1435 On 3 March 2015, the US Examiner responded by rejecting the arguments, on the basis that BlueScope had failed to establish the special measures that were controlled with specificity. The following was said: Response to Arguments 3. Applicant's arguments filed 2/16/2015 have been fully considered but they are not persuasive. Applicant argues essentially that the thickness uniformity or variation as claimed is unexpected result, a benefit of detailed line trials and testing. The examiner notes that initially, the claims as drafted are substantially broader than the factual evidence supports. Since the factual evidence provided by the applicant is clearly insufficient to support the entire range and breadth of the claim, the examiner finds this evidence moot and unpersuasive. Applicant argues continually that extensive line trials and research was undertaken, but this is not persuasive because it doesn't indicate or provide factual evidence that the alleged unexpected results cover the entire range of the claims as drafted (i.e. all substrates, all coating process parameters). Additionally, the thickness variation would be expected to be reduced due to the reduction of size of the Mg2Si attributed to the cooling rate. Applicant cites Page 14-Page 15 of the specification, arguing that the "special operational measures had to be applied to keep variation under control" and that one skilled in the art understands that parameters can be varied to control the line and these special operational measures are not the usual measures employed to control a metal alloy line. This is not persuasive because the claims are substantially broader then argued and the applicant has failed to establish with specificity the special measures that are controlled for the entire breadth of the claim. 1436 Mr Munt's evidence was that the rejection of the US application occurred because BlueScope had responded to the US Examiner by attorney submissions rather than expert evidence from declarants. Such evidence is normally provided in the form of an inventor declaration. 1437 On the advice of its US lawyers, BlueScope abandoned the US application and proceeded by way of a divisional application. 1438 Let me make some other observations. 1439 Mr Munt accepted that it would have been preferable to mention the US application in his affidavit. But he thought that it had probably been omitted because the objection was based around patentability concerning prior art based objections and not objections around sufficiency or enablement. 1440 Further, Mr Munt rejected the proposition that he should have suggested to BlueScope, based on the exchange with the US Patent Office, that it was necessary to amend the specification. He considered that the objection related to patentability over Kurosaki, and that the attempt to provide context for the invention was neither here nor there. Mr Munt explained that it had been difficult to obtain a patent in the United States largely because BlueScope had relied upon attorney submissions rather than an inventor declaration.

Summary 1441 In no case has BlueScope amended the patent specifications which correspond to the 257 Patent in any other jurisdiction before or after grant to clarify the meaning of the phrase "special operational measures". 1442 Let me now turn more directly to the exercise of my discretion.

(e) The exercise of discretion 1443 It is convenient to address five themes. 1444 First, Dongkuk says that the amendment is futile because BlueScope has not complied with the requirements of s 40(2)(a). But BlueScope says that this ground of opposition is not open to Dongkuk in these proceedings, in light of the Full Court's decision in Pfizer and the Full Court's decision in Servier 2016. 1445 Now it is well established that I should not order an amendment of an invalid patent where that patent would still remain invalid despite the amendment. But that is not the present case. I reject Dongkuk's futility argument largely based upon the themes discussed in Pfizer, although I accept that French and Lindgren JJ's views on this aspect were obiter. 1446 Second, in the present case the ground of invalidity sought to be overcome is highly significant. Any amendment to the specification of the 257 Patent, if permitted, would be made almost 10 years after the filing date, some four years after the date of grant and some two years after the commencement of an infringement and invalidity proceeding. Moreover, BlueScope has been using the best method commercially since 2013. 1447 Third, in my view there has not been full and frank disclosure. 1448 BlueScope says that it has provided full and frank disclosure of all relevant matters in support of its application to amend the 257 Patent. It says that the only possible matter which it has failed to disclose is the US prosecution file, which relates to an objection based on novelty and inventive step, and not any ground related to best method. It says that it is apparent from the evidence of Mr Munt that the non-disclosure of the US prosecution history was not deliberate. Further, BlueScope says that it has also provided extensive discovery of all documents it believes are relevant to the question of the best method known to it as at the filing date of performing the invention the subject of the 257 Patent. 1449 Now in making an application to amend a patent, the patentee has a duty to make full and frank disclosure of all relevant matters because the Court must, in the public interest, be satisfied that the amendment is properly allowable before exercising its discretion. This is particularly so because many of the matters which need to be considered on an amendment application are exclusively within the knowledge of the patentee. In particular, the patentee has an obligation to put forward correct reasons for the amendment and there is a corresponding obligation of disclosure of documents explaining those reasons. 1450 I agree with Dongkuk that BlueScope has failed to provide full and frank disclosure for at least the following reasons. 1451 The witnesses relied upon by BlueScope in support of the amendment application have not fully and frankly disclosed all matters in their affidavits relevant to the proposed amendments. Mr Munt failed to disclose that the US Patent Office had rejected the corresponding US application for reasons including that: Applicant cites Page 14-Page 15 of the specification, arguing that "the special operational measures had to be applied to keep variation under control" and that one skilled in the art understands that parameters can be varied to control the line and these special operational measures are not the usual measures employed to control a metal alloy line. This is not persuasive because the claims are substantially broader then argued and the applicant has failed to establish with specificity the special measures that are controlled for the entire breadth of the claim. 1452 This is one of the matters which put BlueScope on constructive notice of the need to amend. The failure to refer to the US application significantly tells against the exercise of the discretion in BlueScope's favour, albeit that in the US context different aspects of invalidity were being addressed. 1453 Now BlueScope does not accept that the reason for the proposed amendment is that the 257 Patent is invalid because it failed to disclose the best method known to it of performing the invention. Rather it puts it no higher than there being a risk that it has not satisfied s 40(2)(a). BlueScope's primary position is that the unamended specification satisfies the obligation required by s 40(2)(a). But on no reasonable view would a person skilled in the art at the filing date understand that the reference in the unamended specification to using "special operational measures" to control short range thickness variation be taken to mean what is expressed in the proposed new text. 1454 Fourth, in my view there has been an unfair advantage to BlueScope by the non-disclosure. 1455 Now BlueScope says that there is no evidence of it having obtained or having sought to obtain an unfair advantage by reason of the fact that the 257 Patent stood unamended. Moreover, it says that there is no basis for concluding that Dongkuk or any person has been disadvantaged by the 257 Patent in its unamended form. Further, BlueScope notes that the proposed amendment does not affect the scope of the claims of the 257 Patent and it does not seek to amend the claims of the 257 Patent. 1456 Further, although Dongkuk asserts that BlueScope has obtained an unfair advantage by seeking to constrain its commercial activity and commencing proceedings for infringement, BlueScope says that it is not apparent how it is said that any disadvantage arises from the failure to include the amendments in the original text. 1457 BlueScope has pointed to the following matters. 1458 It is apparent from the evidence of Mr Lopez (and also Mr Salon) that adjustments to the air knives were well known considerably before the filing date. Let me elaborate on stabilisers. 1459 Mr Lopez worked for BlueScope and its predecessors from 1974 to November 1999. He recommenced employment with BlueScope in June 2008. His evidence is that stabilisers were used on coating lines to produce galvannealed and galvanised steel from 1991. Stabilisers were used in conjunction with wiping jets. The main variables that affected coating weight and consequently coating thickness were the air pressure within the wiping jets and the distance between these jets and the coated strip. BlueScope's predecessor, BHP Steel patented such stabilisers in the early 1990s. More stabilisers were installed in 1993 or 1994. Mr Lopez was aware that stabilisers were also in use on painting lines. Stabilisers were trialled on galvalume in 1993 to 1994. The galvalume manufactured during these extended trials was sold commercially. 1460 Mr Lopez knew that if the stripping jets were moved closer to the metallic coated steel strip, more coating would be stripped-off resulting in a thinner coating. However, operating the stripping jets closer to the metallic coated strip surface increased the likelihood of the molten metallic coating touching the stripping jets and thereby blocking the apertures because of the undesired lateral movement of the coated steel strip. It was therefore important to stabilise the movement of the strip through the jets to reduce the likelihood of the molten metallic coating coming into contact with the stripping jets. 1461 Before the end of 2005, which was after Mr Salon had retired but before the filing date, major global engineering firm ABB announced the development of an electromagnetic stabiliser for application in close proximity to jet wipers on metallic coating lines. ABB also presented at the Galvanizers Association 98th meeting in 2006. It was apparent from this presentation that the strip had been tested on a galvanising line in 2004 to 2005. 1462 Between 2000 and 2007, Mr Lopez was aware of the air flotation stabiliser of Spooner Industries Ltd. In 2001, Spooner presented at the Galvatech conference in relation to its stabiliser. It was apparent from this presentation that Corus UK had installed the stabiliser. 1463 During 2006 to 2007, Mr Lopez became aware of another electromagnetic stabiliser by EMG, a German company who developed a form of electromagnetic stabiliser. EMG gave a presentation on its stabiliser to the Iron and Steel Technology Conference in about 2006. EMG gave a presentation on field tests conducted on ThyssenKrupp Steel's galvanising lines in March 2005. In June 2007, EMG circulated a newspaper indicating that four leading steel producers had installed EMG's electromagnetic strip stabiliser on galvanising lines to ensure uniform coating thickness. EMG circulated a similar newsletter in April 2008. 1464 During 2007, Hatch Engineering worked with JWS of India to assist them with the conversion of two of their galvanising lines to galvalume, and with Spooner who designed and supplied air flotation coolers. 1465 In 2007, SMS reported on its contactless electromagnetic strip stabiliser, which was installed on Hysco's galvanising lines in South Korea in April 2007. 1466 Prior to 2008, Mr Lopez had meetings with Spooner based in the United Kingdom, who was aiming to sell BlueScope equipment and promoted the equipment as suitable for use in BlueScope's facilities, including galvalume facilities. 1467 Also prior to 2008, Mr Lopez had meetings with EMG. EMG offered to loan BlueScope equipment for tests. BlueScope asked EMG if the equipment was suitable for galvalume, given the bath temperature, and EMG said they did not believe there would be a problem in using the equipment for galvalume. 1468 In evidence before me Mr Lopez and Mr Renshaw explained that stabilisers were suitable for use in any hot dip coating line. Mr Lopez explained that references to hot dip galvanising lines simply referred to galvanising processes that could relate to a multitude of alloys. He considered that by 2008, persons skilled in the field of coating had a general understanding of the principles involved in strip stabilisation, irrespective of the alloy coating. 1469 Mr Renshaw explained that since stabilisers had been used on zinc lines and on aluminium lines, it was apparent that they were suitable for use on an Al-Zn-Si based alloy provided a cost-benefit analysis supported their use. Mr Renshaw explained that galvanising was part of the same field as galvalume, that is, metal coating, and that the differences between the coatings were not significant in relation to the issue of whether a stabiliser would work. Mr Renshaw explained: I don't think there was any question that they would work; they would work. It's a matter of what difficulty we - we might have putting them on our lines and retrofitting them… 1470 According to BlueScope, Mr Lopez's evidence was that the stabilisers had been promoted for use with galvalume. It is said that he explained that although manufacturers may not have sold stabilisers for use with galvalume, they had thought through the principles and promoted the product for different coatings. I would note that his precise evidence was as follows: MR COOKE: Now, if I could ask you now to turn to the next annexure in tab 102. This is annexure ML5. It is a June 2007 publication. This refers to the EMG eMASS electro - sorry electromagnetic stabiliser, correct? MR LOPEZ: Yes, the eMASS system I think they call it. MR COOKE: Yes? MR LOPEZ: Yes. MR COOKE: And you can see at the bottom of page E1566 it says: Four leading international steel producer[s] installed a new system for ensuring homogeneous zinc layer thickness. Do you see that? MR LOPEZ: I do. MR COOKE: And that's a reference to it being used in the galvanising and galvannealing context; correct? MR LOPEZ: It doesn't necessarily mean that. Zincalume, Galvalume and similar-type products also have a significant proportion of zinc. MR COOKE: There is nothing in this article- on the face of this article that refers to its use in Galvalume, is there? MR LOPEZ: It doesn't particularly cite that. But my understanding, when I received this newsletter it didn't exclude it either. MR COOKE: And there is no reference in this article to the use of this machine to control short-term thickness variation, is there? MR LOPEZ: Not specifically in a general newsletter publication indicating the development of their technology. But this is also the company that we met with on quite a regular basis and they were even offering to loan us a system to try with Zincalume. So they were very confident that it would work on Zincalume. 1471 Although Mr Lopez was not aware of any electromagnetic strip stabiliser having been used in the galvalume context either before 2010 or between 2010 or 2018, he thought that such stabilisers could be used. Mr Lopez was aware of two examples where an air flotation stabiliser was in use on galvalume lines in India. 1472 Mr Lopez was also cross examined in relation to the issue of whether stabilisers had been promoted for the control of short range coating thickness variations. Mr Lopez's evidence was that BlueScope had had discussions with manufacturers indicating stabilisers were suitable for that purpose. He explained: MR COOKE: In this trial you did not examine sub-five millimetre - - -? MR LOPEZ: We didn't. You're correct. MR COOKE: Yes. That wasn't one of the motivations for putting the air flotation system on MCL1, was it? MR LOPEZ: No, not over standard Galvalume. MR COOKE: No? MR LOPEZ: With different defects we didn't seem to require that capability at that stage, but I think one factor is the strip stabilisation, the movement between the air knives that we've talked quite a lot about yesterday and today. The other one is moving the nozzles closer to the strip means we can run them at a lower pressure and right within that wiping zone, the whole wiping condition improves in terms of stability because the jet stream is at a lower velocity so we have less disturbance right at the wiping point, and that's not measured by any of the documents we've referred to. So we knew that would be the case and it would overcome many other potential defects. … MR COOKE: Yes. And, again, this document indicates that by December 2009 you're still experiencing some detrimental conditions by using the air flotation stabiliser with the Edge coating? MR LOPEZ: Yes, with the - with the particular settings that were used during the trial. I think another important point under that air flotation stabiliser - it talks about reducing vibration but also talks about moving the jets closer. As I mentioned earlier, macrovibrations in the strip are one thing, but we know that operating with the jets closer at a lower pressure and lower gas velocity reduced the vibration and the wiping effects right at the nozzle itself. So we were trying to tackle both. 1473 Mr Dutton gave evidence that the use of stabilisers had been promoted at the 2004 InterZAC Association conference, being a conference for licensees of galvalume, by Spooner in relation to stabilising the coated strip. 1474 Mr Salon says that he was not aware of the commercial use of stabilisers on galvalume coatings. Now BlueScope does not contend that stabilisers were widely used for galvalume. It is apparent from the evidence of Mr Renshaw and Mr Salon that they were not. But stabilisers were promoted for use on galvalume lines from at least about 2007, and skilled addressees were aware that they were suitable for use for that purpose in 2008 and 2009. 1475 BlueScope says that it is apparent that Mr Salon was aware stabilisers could be used on galvalume lines because he was aware that they were under development on alloy coating lines. 1476 Mr Salon retired from full time employment in 2002, some seven years before the filing date. He explained that he had undertaken two months' work for BlueScope since February 2002 including two weeks' employment with Steel Dynamics Inc in 2007, and one month's employment with BlueScope Steel China with troubleshooting on their zincalume line in Suzhou. He did not attend any conferences after February 2002. BlueScope says that it is unsurprising that he was unaware that manufacturers of stabilising equipment were promoting their equipment for use on galvalume lines in 2005 and afterwards. 1477 BlueScope says that it is apparent from the evidence that the skilled addressee in 2008 was aware of air flotation or floater jet stabilisers and electromagnetic stabilisers. By 2007, several major steel companies had installed stabilisers on metallic coating lines. 1478 Further, BlueScope trialled an air flotation stabiliser with galvalume in 2007 because it was not happy with the performance of the standard air knife, which meant that line speed needed to be restricted to achieve product quality. As a result, low coating mass galvalume could not be produced. In particular, when BlueScope ran MCL1, which produced galvalume sheets greater than 1050 mm wide, the after pot system had to run at a pressure which generated instability in the strip causing fluttering. Lighter gauge steel used by BlueScope was more susceptible to vibration. These limitations meant that when BlueScope produced AZ70, it could not run the lines faster than 130 m per minute. BlueScope wanted to move the jets of its air knives closer. But without stabilisers, it was not practical to do so. 1479 Now although Dongkuk attempted to demonstrate that the implementation of air flotation stabilisers was a process attended with difficulty, BlueScope says that the evidence does not support that proposition. 1480 Mr Lopez explained that BlueScope's research and development between 2008 and 2012 was largely driven by the practical constraints associated with a difficult working environment above a molten metal bath, rather than the principles involved in implementing wiping jets in conjunction with a stabiliser. Mr Lopez explained that although it was necessary to learn how to operate the stabiliser with the new coating, the relevant difficulties were able to be overcome without changing the design markedly. 1481 Mr Renshaw explained that some of the trial and error resulted from the fact that BlueScope made its own product, rather than buying from a supplier. Mr Renshaw explained that BlueScope knew that the stabilisers would work, but that it was more a matter of the difficulty BlueScope would have in retrofitting. He explained that BlueScope decided not to purchase from an external supplier for cost reasons and because it had the internal know-how. But it needed to fit the stabiliser into the existing (decades old) line, which required careful consideration. 1482 Mr Lopez's evidence was that the air flotation stabiliser was settled around the end of 2008 or 2009, but that the project was put on hold in the wake of the global financial crisis until 2012. Mr Renshaw also gave evidence that the design of the air flotation stabiliser had been settled by November 2009, but that the global financial crisis delayed the project. 1483 In relation to the system that was built in 2012, Mr Lopez explained to me the following: HIS HONOUR: Sorry, just before you go on, Mr Lopez. Am I to understand this was the first proposal for the detailed engineering as opposed to what I would describe as a concept? Is this the first work for this type of air flotation stabiliser that could be described as something more than just a concept? MR LOPEZ: Your Honour, you could describe it that way, but previously we had fully detailed earlier versions of the [Air Flotation Stabiliser] that had to be engineered with compromises to fit the existing equipment. So we weren't replacing the air knives. We knew there were limitations there like the distance above the air knife was too great - a number of different things. So we had fully designed the system before but under specific or within specific constraints. This was now reflecting on everything we had learned and not only adding AFS but re-engineering that whole system with the air knife and AFS built in to give us more optimal geometry. 1484 I accept much of BlueScope's evidence as to the above matters. But the fact is that BlueScope's failure to disclose in the unamended specification the best method known to it of performing the invention at the filing date has meant that it has obtained an unfair advantage to the detriment of the public such that I ought to exercise my discretion to refuse the amendment application. 1485 An unfair advantage that BlueScope obtained was the inability for others to experiment or improve on the invention. It has sought to protect its invalid monopoly. The public has been disadvantaged by BlueScope's conduct because for the last 10 years it has been deprived of the knowledge of what is the best method of performing the invention. A failure to disclose the best method of performing an invention impedes persons from lawfully exploiting a patent during its term such as acts for experimental purposes (s 119C). The failure also impedes persons from conducting research in other ways that do not constitute exploitation of the invention. It also impedes persons from legitimately seeking to exploit commercially what the patentee has learned whilst avoiding the forbidden territory of the claims. Further, I agree with Dongkuk that it does not have to demonstrate that a member of the public has in fact suffered detriment by BlueScope's failure to disclose the best method. This can be inferred from its failure to comply with its obligations under s 40(2)(a) and the consequential loss of rights available to persons under s 119C. In any event, BlueScope carries the onus of establishing why I should exercise my discretion to allow the proposed amendments. 1486 Further, another unfair advantage that BlueScope obtained was the secret use of the invention. The necessity for BlueScope to elect between preservation of its trade secrets and obtaining patent protection with its disclosure obligations was thereby avoided. It would seem that whilst withholding information from the public, BlueScope applied and optimised the best method known to it of performing the invention during the period 2009 to 2013. And it used that best method commercially from 2013. Mr Renshaw gave the following evidence: Business conditions between the end of 2007 and March 2009 meant that further line trials for Project EDGE were put on hold. This meant that I did not complete the task of optimising the precise parameters for adjusting stripping jets to control short range coating thickness variations and introducing a stabiliser, as I had originally planned. [This] task was not completed on all metal coating lines until February 2012, with further adjustments continuing to be made later in 2012 and 2013 prior to commercial launch of BlueScope's AM product. On 30 June 2008, the Project EDGE Manufacturing Team circulated a process development forward work plan (Work Plan). The Work Plan stated that the next line trials would take place on MCL5 (metal coating line 5) and MCL4 (metal coating line 4) in March and June 2009 (under "Potential Future Trials"). The Work Plan also stated the relationship between cooling rate, coating thickness, impact pressure and mottle had been determined (under the heading After Pot Cooling (Mottle)). The Work Plan also noted an issue in relation to jet stripping equipment and conditions. Namely, that the addition of magnesium may change jet stripping conditions to a set of new, unfamiliar operating conditions (under the heading Issue: Jet Stripping Equipment and Conditions). It was apparent from the work we had already done (and our conclusion that the jet stripping distances would need to be smaller) that it might be necessary to optimise the jet stripping equipment for AM coating lines, including by introducing stabilisers. However, this work did not need to be done until all of the other manufacturing issues identified in the Work Plan had been resolved. The task of optimising jet stripping conditions was therefore a low priority unless a commercially viable AM coated steel could be developed. The Work Plan identified the next steps to be taken by the Project EDGE team, including monitoring the steel strips for mottle in the next line trials (under the heading After Pot Cooling (Mottle). However, we did not propose to take any active steps to reduce mottle in these next trials, given the more significant issues identified in the Work Plan that needed to be solved. … The need to modify coating air knives (jet stripping apparatus) was reflected in the Project EDGE - PSDG (Product Steering and Development Group) Update dated December 2008, which was created by Project EDGE team leader Rob Scott (under the heading "Manufacturing areas of focus"). The jet stripping apparatus used for AZ coating lines was in any event old and would need to be replaced. The update also noted that manufacturing changes, including the coating mass control project, were subject to capital review (under the heading "Project Interaction - Updates in Orange"). … A further line trial was conducted in March 2009 on MCL5 (the March 2009 Trial). The purpose of this trial was to conduct an extended production run of approximately two weeks duration in order to test potential process capability solutions and confirm line upgrade requirements, and to identify if there were any additional manufacturing issues, which were not apparent in the shorter, line trials. Although the task brief identified the need to examine jet stripping parameters, the focus was on reducing pock marks (a different surface defect), by observing the effect of jet stripping parameters on pock marks… The March 2009 Trial was conducted at speeds and cooling rates that would not be suitable for commercial production. Due to the configuration of the line and the lower solidification temperature of the AM coating, unless slower speeds were used the coating would not have solidified by the time it reached the Turn-Around Roll. At the cooling rates which were used, the Project EDGE team did not expect that mottle would result (since, as set out above, the appearance of mottle results in part from the use of higher cooling rates), and we did not observe mottle. Therefore, we did not introduce any measures to address mottle including arrangements to reduce short range coating thickness variations (that is, we did not alter the arrangements of the jets or introduce a stabiliser)… No stabiliser was used in the March 2009 Trial. No further line trial was conducted until November 2009 on MCL4 (the November 2009 Trial). The November 2009 Trial addressed manufacturing issues associated with the manufacture of low coating mass and to diagnose and design a solution for a surface defect, streaking. In this line trial the jets were moved closer to the metal strip for the first time, on an experimental basis, and an air flotation stabiliser was used…One of the aims of the trial was to assess the effectiveness of "Air Floatation Stabilisers" in minimising the jet to strip distance in the jet stripping zone… Like the March 2009 Trial, the November 2009 Trial was run at reduced production speeds (of 175 metres per minute) due to equipment limitations. Therefore, the Project EDGE team did not expect that the process conditions would produce mottle. Consistent with this prediction, no mottle was observed. However, it was not possible to produce a commercially viable product using the reduced production speeds, because production volume was significantly reduced. … Following the November 2009 Trial, the Project EDGE team produced a Project EDGE Manufacturing Update in December 2009. That update said that the best AM product to date had been produced when the line was stabilised with an Air Floatation Stabiliser (AFS) allowed successful jet stripping at 15mm jet to jet distance (which is a jet to strip distance of 7.5mm), and that initial indications suggested the AFS reduced strip vibration by a factor of 4. The update focused on other defects. It did not mention mottle… On 24 December 2009, I created a document analysing the effect of the AFS on strip position and stability, based on the results of the November 2009. I concluded that the effect of the AFS on strip stability is significant even at pressures of approximately 2 kPa. The magnitude of the improvement seemed dependant on the level of instability with the AFS off. … In 2011 the Project EDGE team ran an eight week line trial on MCL4 at speeds between 80% and 100% of normal commercial speeds, depending on the thickness of the strip. In this trial the first commercial air flotation stabiliser was used and the position of the jets were modified… It was still necessary to modify the upleg cooling equipment (to allow production of the full range of strip thicknesses at commercial speeds) and arrive at the commercial specifications for the jet equipment (to prevent excessive short range coating thickness variations). These modifications were made in 2012… In 2012 the Project EDGE team ran two further line trials on MCL1. The first line trial in February 2012 was to test the implementation of the solution to surface streaks and to confirm successful operation of the final jet modifications. These modifications consisted of an air floatation stabiliser that was integrated with the jet support system and a new narrow bodied jet barrel design. These jet modifications enabled a reduction in the jet height above the bath and a reduction in the jet to strip distance. The updated jet stripping equipment was designed and constructed by Hatch Engineering to BlueScope specifications. In October 2012, further modifications to MCL1 were made. These modifications included an extra cooling zone in the upleg cooling section to increase the overall cooling capacity and redesign of the cooling control system to allow for the restrictions in cooling rate identified in the earlier work on mottle. The modifications to the upleg cooler design and control systems were undertaken by BlueScope engineering personnel. The second line trial in December 2012 related to issues with chemical passivation and was to confirm successful operation of the upleg cooler modifications which had been made in October 2012. In both of these trials an integrated air flotation stabiliser was used (which was an updated version of the air flotation stabiliser used in the 2011 trial on MCL4) and the position of the jets were further modified… In 2013 the Project EDGE team conducted a final line trial on MCL4 to confirm production capability for AM coated steel. This included use of final modifications to the upleg cooler and modified jet stripping conditions… Following the successful completion of the 2013 line trial, AM coated steel was launched by BlueScope in 2013. 1487 Finally, I agree with Dongkuk that BlueScope sought to obtain an unfair advantage by threatening Dongkuk during the period June to December 2016 with infringement proceedings on the unamended 257 Patent. At that time, BlueScope knew or ought to have known that it had not disclosed the best method and that for at least that reason the 257 Patent was invalid. BlueScope sought to obtain a further unfair advantage by commencing infringement proceedings on the unamended 257 Patent some four months before it filed the amendment application. 1488 Fifth, in my view there has been unreasonable delay in seeking the amendment. 1489 BlueScope says that it has moved expeditiously in making its application to amend the 257 Patent and that there has been no unreasonable delay. Let me elaborate on its submissions. 1490 BlueScope says that it acted expeditiously to include what it considered to be the best method known to it of performing the invention as soon as it was alerted by its solicitors and counsel to the prospect that it might be necessary to amend the 257 Patent. 1491 Further, it says that it was reasonable for it not to amend the 257 Patent despite the fact that the APO raised the issue of best method in its Second Examination Report in September 2014. In light of Mr Munt's response, no amendment was required by the APO. Mr Munt considered that the issue had been dealt with and therefore did not recommend amendment. And the 257 Patent proceeded to grant. 1492 Further, it says that it was also reasonable for it not to amend the 257 Patent despite the adverse reports in China, South Korea, Japan and the United States. Following BlueScope's responses to the adverse reports in China, South Korea and the first office action in Japan the objections were resolved. No Patent Office required an amendment to be made. Further, although BlueScope did not press its divisional application in Japan, it had filed another patent. Further, it says that the adverse report from the United States Patent Office related to whether the claimed invention was anticipated, not sufficiency or enablement. 1493 Further, it says that when it was first alerted by its solicitors and counsel on 5 October 2016 that it might be necessary to amend the 257 Patent, it undertook extensive investigations to identify the state of BlueScope's knowledge at the date of filing, whether amendment was necessary, and ultimately the appropriate form of the amendment required. 1494 Now unreasonable delay is a compelling reason for refusing an application to amend a patent. In Smith Kline & French Laboratories Ltd v Evans Medical Limited [1989] 1 FSR 561, Aldous J stated at 568: [I]n a case where a patentee who is aware of the facts and either decides not to amend or takes no action, but later changes his mind, the court will refuse to exercise its discretion in his favour unless there is a good and proper reason for his failure to seek amendment promptly. 1495 This encompasses a situation where a patentee is aware that there is a significant risk of invalidity if it maintains the patent in its unamended form. Constructive knowledge of the patentee may also be relevant. Indeed, the Full Court in Servier 2016 also held that constructive knowledge of the need to amend the patent is sufficient for establishing unreasonable delay. In particular, the Full Court at [243] held that: … • Unreasonable delay is a circumstance likely to lead to refusal of the amendment. … • In assessing delay, the time when the patentee was unaware and reasonably did not know of the need for amendment is not taken into account. The relevant delay is from when the patentee knows of the likely invalidity, or has its attention drawn to a defect in the patent, or is advised to strengthen the patent by amendment. That is, amendment will not be permitted in cases where a patentee knows or ought to know that amendment should be sought and fails to do so for a substantial period of time. Thus the reasonableness of the conduct of the patentee is a relevant consideration when assessing delay. 1496 In my view BlueScope has unreasonably delayed in seeking amendments to the 257 Patent. 1497 It is not in dispute that BlueScope knew of the best method of performing the alleged invention before the filing date notwithstanding that it had not in fact applied those "special operational measures". 1498 Further, BlueScope applied and optimised the best method known to it of performing the alleged invention during the period 2009 to 2013 and used that best method commercially from 2013. 1499 Further, during at least the period 2012 to 2014, through the prosecution of foreign equivalent patents to the 257 Patent in at least China, the United States and South Korea, BlueScope was made aware or ought reasonably to have been aware that the specification of the 257 Patent did not disclose any method, let alone the best method known to BlueScope, of achieving minimal variation in the short range coating thickness to achieve the described distribution of Mg2Si particles in the surface of the coating. This is evident from various documented comments made to BlueScope by the Patent Offices in those jurisdictions. I have set some of these out earlier. 1500 Further, on 4 September 2014, in the second examination report in respect of the 257 Patent, the examiner expressly raised a failure to disclose the best method. The examiner said: I am not currently satisfied that the present specification provides an enabling disclosure of how to provide a strip with a variation in thickness of the coating of now [sic] more than 40% in any 5 mm diameter section and / or a best method of achieving this particular result… Reviewing the specification as a whole, I can find no disclosure of what those special conditions are so as to provide the defined thickness variation…I am not satisfied that the subject matter claimed is provided with a best method of performance… even if a manner of performing the invention is self-evident, applicants are nevertheless required to set out the best method of performing the invention known to them. 1501 Notwithstanding that express notification, BlueScope did not amend the 257 Patent specification. Instead on 5 September 2014 it advocated a position to the office in the following terms: The skilled person in the field is a person who has experience in operating metal alloy coating lines and therefore understands the parameters that can be varied to control the line and, in particular, would understand the "special operational measures" mentioned in the…specification that could be applied to achieve the necessary control. The term "special" is intended to be understood in this context that they are not the usual measures employed to control a metal alloy coating line… By way of example, the skilled person would understand that control of the gas stripping equipment that controls coating thickness is one of a number of measures that have an impact on controlling short range thickness variations of coatings. One particular control measure for the skilled person is to adjust the height of the stripping knife above the coating bath… 1502 Further, on 8 January 2015, the 257 Patent in its unamended form was granted. 1503 Further, on 16 February 2015, in response to a US office action, BlueScope referred to the special operational measures that had to be applied to keep the variation under control as a basis for an amendment to one of the claims. 1504 Further, on 3 March 2015, the US Patent Office responded in relation to application no. 12/811,213: Applicant cites Page 14-Page 15 of the specification, arguing that the ["]special operational measures had to be applied to keep variation under control" and that one skilled in the art understands that parameters can be varied to control the line and these special operational measures are not the usual measures employed to control a metal alloy line. This is not persuasive because the claims are substantially broader then argued and the applicant has failed to establish with specificity the special measures that are controlled for the entire breadth of the claim. 1505 Further, on 18 March 2016, in response to US Patent Office action #6, BlueScope said: …The specification makes it clear that the key findings of the line trials led to the subject invention. The purpose of the line trials was to investigate the impact of cooling rates and coating masses on mottling in the surface of coatings… In fact, whilst not described explicitly in the specification, the production line included gas wiping technology to control the thickness of coatings on steel strip emerging from the coating bath of the production line… 1506 Further, on 6 June 2016, BlueScope sent a letter of demand to Dongkuk threatening infringement proceedings in relation to the unamended 257 Patent. 1507 Further, on 21 June 2016, the Japanese Patent Office notified BlueScope in relation to a divisional patent based on JP application no. 5850619 that: …it is not categorically described in the specification what conditions may be adjusted in the hot-dip coating method in order to satisfy the feature that "an alloy coating is formed on the strip with a variation no more than 40% in any given 5 mm diameter section of the coating". Therefore, a large amount of trials and errors are needed to find the specific condition of the hot-dip coating method from all adjustable experimental conditions even if considering common general technical knowledge at the time of filing the present application, and it is not recognized that a person with ordinary skill in the art can carry out the inventions of Claims even if considering common general technical knowledge at the time of filing the present application in the whole specification. 1508 Further, on 29 July 2016, a third party filed an opposition in respect of Japanese patent no. 5850619 alleging that the "special operational measures" are neither described nor suggested in the detailed description of the invention. 1509 Further, on 13 December 2016 BlueScope commenced infringement proceedings against Dongkuk in relation to the unamended 257 Patent. 1510 Finally, and belatedly, BlueScope filed the amendment application on 13 April 2017. 1511 In summary, it would seem from the evidence that BlueScope's lawyers and attorneys had to explain, by reference to matters beyond what was apparent from the specification, to Patent Offices in Australia, South Korea, Japan and the US, what was meant by "special operational measures" in order to try to overcome objections to applications for patents in those countries for the invention in suit. Clearly, BlueScope was on notice of the need to explain that expression in the specification. As Jessup J explained in CSL Ltd v Novo Nordisk Pharmaceuticals Pty Ltd (No 2) (2010) 190 FCR 522 at [76] with his customary pellucidity: …a patentee who has been exposed to facts from which it was, or reasonably ought to have been, apparent to him or her that a claim might well be invalid unless amended, and who later seeks the favourable exercise of the Court's discretion under s 105 is, in my opinion, in no position to say that there was, on the earlier occasion, no "need" to amend simply because it had not then been conclusively established that the claim was in fact invalid… 1512 At the least BlueScope had constructive knowledge of the need to amend the specification well before it did so and simply made a calculated decision to take its chances with the disclosure it had made, whilst simultaneously benefiting commercially from the best method to the detriment of the public. I agree with Dongkuk that BlueScope should be held to that choice by my refusing the amendment.

(f) Summary 1513 Taking into account the foregoing matters and also the other considerations raised in the parties' submissions, in the exercise of my discretion I would refuse the amendment.

CONCLUSION 1514 BlueScope has failed on its infringement case. 1515 Dongkuk has partly succeeded on its invalidity case concerning the failure by BlueScope to disclose the best method known to it at the relevant time. Otherwise its invalidity case has failed on all other grounds. 1516 BlueScope has failed on its amendment application. 1517 I will hear further from the parties concerning the orders to give effect to these reasons, the resolution of any outstanding issues, and on costs. I certify that the preceding one thousand, five hundred and seventeen (1517) numbered paragraphs are a true copy of the Reasons for Judgment herein of the Honourable Justice Beach.