T 0044/05 11-01-2008

I. The patent proprietor lodged an appeal against the decision of the Opposition Division to revoke European patent No. 0 743 370.

II. An opposition had been filed against the patent as a whole under Article 100(a) EPC on the grounds of lack of novelty and inventive step, and under Article 100(b) EPC, that the patent does not disclose the invention in a manner sufficiently clear and complete for it to be carried out by the person skilled in the art.

The Opposition Division held that claims 1 to 11 of the main request dated 26 July 2004 and of the auxiliary requests I and II as filed at the oral proceedings of 6 October 2004 met the requirements of Articles 123(2) and (3) EPC and of Article 100(b) EPC. The Opposition Division further considered that the subject-matter of claims 1 and 7 of the main request was novel with respect to D1 to D4 but that the subject-matter of claim 11 was not novel as it did not meet the requirements for a selection invention with respect to D2 (EP-A-0 566 986). Furthermore, the subject-matter of claims 1 and 11 of the main request was considered to lack an inventive step with respect to D1 (JP-A-05 306 410). The subject-matter of claims 1, 7 and 11 of auxiliary requests I and II was considered to be novel but the subject-matter of claim 11 of both requests was considered to lack an inventive step in view of D2.

III. With a communication dated 10 September 2007 annexed to the summons to oral proceedings the Board presented its preliminary opinion based on claims 1 to 11 of the main request and of the auxiliary requests I to III, all requests as submitted with the grounds of appeal dated 23 February 2005.

III.1 The Board gave its preliminary opinion that, among

others, the main request seemed to meet the requirements of Article 123(2) EPC while the independent claims of auxiliary request I appeared to contravene Article 123(2) EPC.

With respect to the "closed definition" (=100%) of the steel compositions in claims 1, 7 and 11 as granted ("comprises in weight percent, ..., the balance being iron and unavoidable impurities") these steels cannot contain any deliberately added elements other than those specified, but may contain other elements falling under the definition "unavoidable impurities". Thus, there would be an inconsistency between paragraphs [0035] and [0046] of the description concerning the deliberate additions of molybdenum or of other elements and claims 1, 7 and 11 of all requests.

III.2 The subject-matter of claim 11 of all requests seemed

to be novel, particularly with respect to the steel compositions of D2.

With respect to inventive step the Board stated that D2 seemed to represent the closest prior art. Furthermore, taking account of the different steel compositions of all examples of the patent in suit and the "comparative" examples therein, which correspond to the teaching of prior art documents different from D2 (see patent, Tables 1-8) it seemed to be difficult to derive which effect is caused by the feature Mneq and the content of Si, Mn, Cr, Ni, Cu, etc. and whether there exists any improvement over the electrical steel sheets according to D2 since no comparison was available.

Claim 11 of the main request appeared to be distinguished from D2 by a minimum Mneq value of at least 0.5%, a minimum volume resistivity of at least 50 myOmegacm, a certain range for the %Si-0.45 %Mneq value from 2 to 4.4 and a minimum volume fraction of the austenite of at least 5%. Taking account of the missing comparison with D2 in the patent in suit and of the overlap of the concentration ranges of the relevant elements of the electrical steel sheet composition according to D2 it had to be considered that some compositions based on the preferred Si-content of 3.4% Si, the C-content of from 0.025-0.075 % and the maximum Mn-content of 0.8% (optionally additionally comprising 0.03-0.2% Cr) met these four claimed requirements, even though the latter were not explicitly mentioned in D2. Thus it seemed reasonable to define a less ambitious objective technical problem of simply providing an alternative steel composition for a process for producing grain oriented electrical steel sheet having an aluminium nitride inhibitor system (see Case Law of the Boards of Appeal of the European Patent Office, 5th edition 2006, chapter I.D.4.5). Thus it needed to be discussed whether or not the person skilled in the art would seriously contemplate to work in the mentioned overlapping ranges, particularly as there appeared to exist no prejudice to use a Mn-content of up to 0.8%.

III.3 The parties were given the opportunity to file

observations to the communication which should be filed well in advance, i.e. at least one month, before the date of the oral proceedings.

Finally, the parties were advised to take note of the Rules of Procedure of the BoA, in force as of 1 May 2003 and especially of Article 10b (as of 13 December 2007: Article 13).

IV. With letter dated 10 December 2007 the appellant (patent proprietor) filed an amended main request and amended auxiliary requests I to III.

V. Oral proceedings before the Board were held on 11 January 2008. With respect to the main request the discussion concentrated on the issues of admissibility of the amendments and inventive step with respect to claim 11 in relation to documents D2, D3 (Houdremont, Handbuch der Sonderstahlkunde, 1956, pages 473 and 474) and D4 (US-A-5 250 123) - all documents of the opposition proceedings and referred to in the appeal proceedings. With respect to auxiliary requests I and II only their admissibility under Articles 123(2) and (3) EPC was discussed. In the course of the oral proceedings four consecutive versions of auxiliary requests I and two consecutive versions of auxiliary request II, each time replacing the previously submitted version, were discussed. Auxiliary request III dated 10 December 2007 was withdrawn at the oral proceedings.

(a) The appellant requested that the decision under appeal be set aside and the patent be maintained on the basis of the main request filed with letter dated 10 December 2007 or, in the alternative, on the basis of auxiliary request I or II filed at the oral proceedings.

(b) The respondent (opponent) requested that the appeal be dismissed.

At the end of the oral proceedings the Board announced its decision.

VI. Claim 11 according to the main request reads as follows:

"11. A grain oriented electrical steel melt, comprising, in weight percent, greater than 2.25 - 5% Si, 0.01 - 0.08% C, 0.015 - 0.05% Al, up to 0.01 % S, 0.001 - 0.011 % N, 0.5 - 4.5 % Mn, Mneq of at least 0.5 %, said Mneq being defined as % Mneq = %Mn + 1 .5(%Ni) + 0.5(%Cu) + 0.1 (%Cr), and optionally up to 3% Cr, up to 1% Cu, up to 2% Ni, the balance being iron and unavoidable impurities to provide a volume resistivity of at least 50 micro-ohm-cm of the final electrical steel, said volume resistivity being defined as vol. resistivity = 9.2 + 12.2% Si + 4.6(%Mn + %Cr) + 2(%Cu) + %Ni, said steel composition balanced such that 2.0 <= [(% Si) - 0.45 (% Mneq)] <= 4.4 and such that a volume fraction of austenite gamma1150ºC in a hot rolled band produced from said melt is at least 5 % up to 40%, said gamma1150ºC being defined as gamma1150ºC = 15.1 (%Mneq) + 784 (%C) - 33.7 (%Si) + 88.7."

VII. Claims 1, 4 and 7 according to auxiliary request I read as follows:

"1. A method of producing grain oriented electrical steel having an aluminum nitride inhibitor system, said method comprising the steps of: a) providing a hot rolled band which comprises, in weight percent, 3.72 - 5 % Si, 0.054 - 0.08 % C, 0.024 - 0.05 % Al, 0.002 up to 0.01 % S, 0.8 - 4.5 % Mn, at least 0.82 % Mneq, said Mneq being defined as % Mneq=%Mn + 1.5(%Ni)+0.5(%Cu)+0.1(%Cr), 0.007 - 0.011 % N, up to 3 % Cr, up to 1% Cu, up to 2% Ni, 0.001 up to 0.1%Sn, 0.014 up to 0.5% P, up to 0.01 % Se and up to 0.1 % Sb, the balance being iron and unavoidable impurities to provide a volume resistivity of at least 58.6 micro-ohm-cm, said volume resistivity being defined as vol. resistivity = 9.2 + 12.2 % Si + 4.6(%Mn +%Cr) + 2(%Cu) + %Ni, said steel composition balanced such that 3.35 <= [(% Si) - 0.45 (%Mneq)] <= 4.4; b) providing gamma1150ºC in said band of at least 5 % up to less than 40 % ; said gamma1150ºC being defined as gamma1150ºC = 15.1(%Mneq)+784(%C)-33.7(%Si)+88.7; c) initial annealing said band by heating said band to a temperature of 900 to 1150ºC for a soak time of 180 seconds or less and heating said band to a secondary soaking temperature of 775 - 950ºC for a soak time of from 0 - 300 seconds and cooling; d) cold rolling said annealed band in 1, 2 or more stages to a final strip thickness, e) decarburizing said strip to a carbon level below 0.005%; f) nitriding said band following primary recrystallization and prior to secondary grain growth to provide excess nitrogen; g) providing said strip with an annealing separator coating at a stage selected from the group of before nitriding, after nitriding or between nitriding treatments; h) final annealing said coated strip at a temperature of at least 1100ºC (2010ºF) for at least 5 hours to effect secondary grain growth and purification."

"4. A method for producing regular grain oriented electrical steel having at least 94.1% of saturation at 795.77 A/m (10 oersteds), comprising the steps of: a) providing a band having a thickness of from 1.0 - 3.0 mm, said band comprising, in weight percent, 3.72 - 5 % Si, 0.054 - 0.08 % C, 0.024 - 0.05 % soluble Al, 0.002 up to 0.01 % S, 0.8 - 4.5 % Mn, up to 3 % Cr, up to 1 % Cu, up to 2 % Ni, greater than 0.82 % Mneq, said Mneq being defined as % Mneq = %Mn + 1.5(%Ni) + 0.5(%Cu) + 0. 1(%Cr), 0.007 - 0.011 % N and balance being iron and unavoidable impurities to provide a volume resistivity of at least 50 micro-ohm-cm, said volume resistivity being defined as vol. resistivity = 9.2 + 12.2 % Si + 4.6(%Mn + %Cr) + 2(%Cu) + %Ni, said steel composition balanced such that 3.35 <= [(% Si) - 0.45 (%Mneq)] <= 4.4; b) annealing said band at a temperature of from 900 - 1125ºC (1650 - 2050ºF) for a time up to 10 minutes, said annealed band having gamma1150ºC of at least 10 % up to less than 40 %, said gamma1150ºC being defined as gamma1150ºC = 15.1(%Mneq) + 784(%C) - 33.7(%Si) + 88.7; c) cold rolling said annealed band in a single stage with a final reduction of greater than 75 to 93 % to final gauge strip; d) decarburizing said strip to a carbon level less than 0.005%; e) nitriding said strip to provide a minimum level of nitrogen of at least 150 ppm; f) providing said strip with an annealing separator coating; and g) final annealing said coated strip for a time and temperature sufficient to develop secondary recrystallization and provide a percent of saturation of at least about 94.1 %, said percent of saturation being defined as % saturation at 795.77 A/m = B(in Teslas at H = 795.77 A/m)/[Atomic % Fe + Atomic % Ni]/0.0002115."

"7. A grain oriented electrical steel melt, comprising, in weight percent, 3.72 - 5% Si, 0.054 - 0.08% C, 0.024 - 0.05% Al, 0.002 up to 0.01 % S, 0.007 - 0.011 % N, 0.8 - 4.5 % Mn, Mneq of at least 0.82 %, said Mneq being defined as % Mneq = %Mn + 1.5(%Ni) + 0.5(%Cu) + 0.1 (%Cr), up to 3 % Cr, up to 1 % Cu, up to 2 % Ni, the balance being iron and unavoidable impurities to provide a volume resistivity of at least 58.6 micro-ohm-cm of the final electrical steel, said volume resistivity being defined as vol. resistivity = 9.2 + 12.2% Si + 4.6(%Mn + %Cr) + 2(%Cu) + %Ni, said steel composition balanced such that 3.35 <= [(% Si) - 0.45 (% Mneq)] <= 4.4 and such that a volume fraction of austenite gamma1150ºC in a hot rolled band produced from said melt is at least 5 % up to less than 40 %, said gamma1150ºC being defined as gamma1150ºC = 15.1 (%Mneq) + 784 (%C) - 33.7 (%Si) + 88.7."

VIII. Claim 1 according to auxiliary request II reads as follows:

"1. A method of producing grain oriented electrical steel having an aluminum nitride inhibitor system, said method comprising the steps of: a) providing a hot rolled band which comprises, in weight percent, 3.69 - 5 % Si, 0.049 - 0.08 % C, 0.027 - 0.05 % Al, 0.002 up to 0.01 % S, 0.81 - 4.5 % Mn, at least 1.08 % Mneq, said Mneq being defined as % Mneq = %Mn + 1.5(%Ni) + 0.5(%Cu) + 0.1(%Cr), 0.008 - 0.011 % N, 0.27 up to 3 % Cr, 0.16 up to 1% Cu, 0.11 up to 2% Ni, 0.013 up to 0.1 % Sn, 0.022 up to 0.5% P, up to 0.01 % Se and up to 0.1 % Sb, the balance being iron and unavoidable impurities including at least 0.035 % Mo to provide a volume resistivity of at least 59.9 micro-ohm-cm, said volume resistivity being defined as vol. resistivity = 9.2 + 12.2 % Si + 4.6(%Mn +%Cr) + 2(%Cu) + %Ni, said steel composition balanced such that 3.2 <= [(% Si) - 0.45 (%Mneq)] <= 4.4; b) providing gamma1150ºC in said band of at least 5 % up to less than 40 % ; said gamma1150ºC being defined as gamma1150ºC = 15. 1(%Mneq) + 784(%C) - 33.7(%Si) + 88.7; c) initial annealing said band by heating said band to a temperature of 900 to 1150ºC for a soak time of 180 seconds or less and heating said band to a secondary soaking temperature of 775 - 950ºC for a soak time of from 0 - 300 seconds and cooling; d) cold rolling said annealed band in 1, 2 or more stages to a final strip thickness, e) decarburizing said strip to a carbon level below 0.005%; f) nitriding said band following primary recrystallization and prior to secondary grain growth to provide excess nitrogen; g) providing said strip with an annealing separator coating at a stage selected from the group of before nitriding, after nitriding or between nitriding treatments; h) final annealing said coated strip at a temperature of at least 1100ºC (2010ºF) for at least 5 hours to effect secondary grain growth and purification."

IX. The appellant argued essentially as follows:

The amendments made to claim 11 of the main request, which is based on claim 11 as granted, are based on claim 10 as originally filed in combination with page 7, lines 22 to 29, page 8, line 27 to page 9, line 6 and lines 12 to 15, page 10, lines 7 to 12 and lines 13 to 33 of the application as originally filed and are in line with the practice of the Boards of Appeal (see Case Law of the Boards of Appeal of the European Patent Office, 5th edition 2006, section III.A.2.1; see T 925/98 of 13 March 2001, not published in OJ EPO). The respondent's belated objections under Article 123(2) EPC, made for the first time in the oral proceedings before the Board, violate Article 10b of the RPBA (2003) and no inconsistencies can be seen to exist between Figures 1 and 2 on the one hand and the description and the ranges of claims 1, 7 and 11 on the other hand. The quoted passage at page 10, lines 7 to 10 of the application as originally filed states that the Mn content "is typically about 0.5 to about 3.0% with about 3.1 to about 4.75% Si" which definition does not exclude that the Mn-concentration may be different. Thus the requirements of Articles 123(2) and (3) EPC are met for claim 11 of the main request.

The subject-matter of claim 11 of the main request is novel for the reasons as set out in the Board's communication accompanying the summons to oral proceedings. In respect of inventive step: as derivable from the description of the patent, composition claim 11 relates to a specific class of alloy materials based on an AlN grain growth inhibitor system and "low reheat technology" which must have transcritical behaviour to be suitable for low reheating in order to achieve a high degree of orientation during the secondary grain growth and to obtain excellent magnetic properties of the resulting electrical steel sheets (see page 1, lines 25 to 30; page 2, lines 3 to 6 and lines 21 to 36; page 3, lines 10 to 22). Furthermore, to achieve a specific volume resistivity and a specific austenite fraction the concentrations of Si, C, Mn, etc. had to be carefully adapted (see page 8, lines 5 to 10 and line 35 to page 9, line 8, and line 30 to page 10, line 2, and line 34 to page 11, line 5). D2 does not suggest such a composition and is silent about Mneq. The person skilled in the art taking account of the 57 examples in D2, which all involve Mn in the low range of about 0.13-0.14% and thus are far distant from the claimed range of 0.5-4.5% Mn according to claim 11, would not seriously contemplate to work in the higher part of the range of 0.05-0.8% Mn claimed in D2, i.e. would not use high Mn-contents, particularly since they deteriorate the magnetic properties (see D2, page 4, line 13 ff; page 8, lines 19 to 23). The question of inventive step in the present case is a typical "could-would" issue. In any case, the claims of D2 do not reflect the actual teaching of D2.

The calculations based on the equations of the patent in suit, using the values of the examples of D2, represent an ex-post facto analysis of this document. The teaching of D2 cannot be combined with that of D4 either, since the latter concerns a totally different system, i.e. ultra low carbon, which contains <= 0.015% Al and uses a different %Si-0.45 %Mneq value, namely less than 2.0, which does not need any decarburizing treatment (see D4, column 2, lines 42 to 49; column 3, lines 9 to 17; column 11, lines 29 to 35).

The problem starting from D2 is to provide good magnetic properties and to provide a stable system for secondary grain growth. Although the composition of claim 11 according to the patent in suit provides similar magnetic properties as the compositions of D2 it provides a different, i.e. sharper, texture. Unfortunately, no evidence showing the improvements can be offered.

It is not relevant for inventive step that the patent in suit contains examples of which the concentrations for Mn are outside the ranges of claim 11.

The subject-matter of claim 11 is thus neither rendered obvious by D2 nor by a combination of D2 and D4.

The amended values of the ranges in claims 1, 4 and 7 according to auxiliary request I are based on example AE in the patent in suit. Taking account of the general disclosure of the application (see page 8, line 29; page 10, lines 10 to 33) underlying the patent in suit and in the light of decision T 201/83 (EPO OJ 1984, 481) it is not apparent that the subject-matter claimed should be restricted to the combination of all the concentration, property and ratio values of this example as the minimum values of the ranges claimed. The specific amounts of Mo, Cr, Ni, Cu, P, Sn, etc. used in this example are not closely related with the other features of the example and thus can be neglected. These values therefore need not be incorporated in claims 1, 4 and 7. The value of 3.35 for the lower limit of the [(%Si)-0.45(%Mneq)]-value was recalculated from the concentration values of 3.72% Si and 0.8% Mn taken from example AE.

The amended values of claim 1 according to auxiliary request II are taken from example AC. Furthermore, taking account of paragraph [0035] of the patent in suit, which mentions generally elements of minor importance, Mo can be present in the steel composition as an unavoidable impurity. The Mo-content of 0.035% represents the level of such an impurity. Consequently, the amendment "at least 0.035% Mo" contravenes neither Article 123(3) EPC nor Article 123(2) EPC.

X. The respondent argued essentially as follows:

The concentration range "0.5 to 4.5% Mn" of claim 11 of the main request has no basis in the application as originally filed. Figures 1 and 2 of the application show that the Mn-content or Mneq is connected with a specific Si-content and that a combination of the minimum values of 0.5% Mn and 2.25% Si is excluded. The same can be derived from the description where it is stated that the levels of Mn are varied depending on the amount of Mneq and Si and that 0.5% Mn is linked with a concentration of Si of at least 3.1% (see page 10, lines 7 to 10). The arguments under Article 123(2) EPC were brought forward as late as the oral proceedings, because the file had only recently been taken over from a colleague, who had not seen this issue.

Novelty of the subject-matter of claim 11 of the main request was no longer contested.

Inventive step: D2 concerns also an electrical steel having a similar composition with concentration ranges broadly overlapping with those of claim 11 of the main request. D2 aims to provide a method which enables good magnetic properties to be stably obtained on the condition that the heating of the slab is effected at low temperature (see page 4, lines 8 to 12). D2 further mentions the grains obtaining a sharp {110}<001> texture in the secondary grain growth (see page 4, lines 17 and 18). Thus D2 aims to solve the same problem as the patent in suit. D2 also suggests increasing the Si-content in its AlN inhibitor system to realize a high magnetic flux density (see page 4, lines 36 to 41). The person skilled in the art would consider the whole concentration range of 0.05-0.8% Mn claimed in D2 to be suitable for obtaining electrical steel sheet having good magnetic properties, since only values exceeding 0.8% Mn are stated to be unfavourable for the magnetic flux density. Therefore the upper limit for the person skilled in the art starting from D2 is 0.8% Mn (see D2, page 8, lines 19 to 23) and there is nothing withholding him from carrying out D2's invention in the overlapping range of 0.5-0.8% Mn. Furthermore, the examples V, W and X made in accordance with D4, which is cited as comparative prior art in the patent in suit (see page 10, Table 4), show that it was already known to use higher Mn-contents. In this context it should be considered that it is very difficult and expensive to produce experimental alloys in preparation of patent applications, which may be the reason for the limited Mn-contents according to the examples of D2. Furthermore, it is known that Mn is effective at causing alpha-gamma-transformation and that is the reason for adding it (see D4, column 5, lines 19 to 21). This fact belongs also to the common general knowledge of the person skilled in the art (see D3, pages 473 and 474) so that there exists the clear teaching for the skilled person to work in the whole range of D2. Compared with the electrical steel sheets of the examples of D2 no further or surprising technical effect can be seen. Therefore claim 11 lacks an inventive step in view of D2. It is admitted that D4 concerns a different steel system than the one disclosed in D2.

The amendments of claims 1, 4 and 7 of auxiliary request I contravene Article 123(2) EPC since the concentrations of the elements of example AE which define the essential features such as Mneq, the [(%Si)-0.45(%Mneq)]-value, the amount of austenite, the volume resistivity, etc. are actually closely related to each other so that the amendments are contrary to the principles set out in T 201/83 (supra). Furthermore, the values for the elements Cr, Cu and Ni are not defined for example AE since only an upper limit is indicated ("<=.01") (see patent, page 11, Table 7). However, these three elements have been present in the steel composition of example AE since otherwise the value "0" would have been mentioned. Paragraph [0035] of the impugned patent specifies that elements such as N, Sn, P, Mo, Sb and the like will also affect the amount of austenite and must be considered (see page 5, lines 29 to 31), so cannot be neglected. These elements, insofar as present in the example AE, were lacking in these claims of the patent in suit.

Example AC on which the further amendments of claim 1 of auxiliary request II are based specifies 0.035% Mo which amount is about 3-times as high as that of Sn. However, the minimum amount of Sn, which together with Mo and further elements is mentioned in paragraph [0035] of the patent as non-neglectable, is specified in claim 1 as purposive choice, whereas the content of Mo is merely specified as an "unavoidable impurity". This is contradictory as said amount of 0.035% Mo cannot represent an impurity level. Consequently there exists no support to this amendment in the application as originally filed. Therefore claim 1 of auxiliary request II contravenes Article 123(2) EPC.