DETAILED ACTION
Status of Claims
Claims 1 and 2 are pending. Of the pending claims, claim 1 is presented for examination on the merits, and claim 2 is withdrawn from examination.
Claim 1 is currently amended. Claim 2 is withdrawn-currently amended.
Claim Rejections - 35 USC § 103
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claim 1 is rejected under 35 U.S.C. 103 as being unpatentable over US 2013/0133783 (A1) to Yamaguchi et al. (“Yamaguchi”) in view of US 2013/0130043 (A1) to Omura et al. (“Omura”) and further in view of US 2014/0338792 (A1) to Takajo et al. (“Takajo”) and KR 10-2009-0116516 (A) to Kwon et al. (“Kwon”) (abstract and computer-generated translation in file as of 09/05/2025).
Regarding claim 1, Yamaguchi discloses a grain oriented electrical steel sheet having a magnetic domain structure modified by strain. Abstract. Strain is introduced onto a side of the steel sheet (strain-introduced surface on one of the sides of the steel sheet). Para. [0012], [0013], [0030].
The magnetic flux density B8 is 1.92 T or higher. Para. [0022].
The steel sheet has an average width of the magnetic domain discontinuous portion in the untreated surface (Wd) (corresponds to average width of the magnetic domain discontinuous portion on the non-strain-introduced surface) and an average width of a magnetic domain discontinuous portion resulting from the strain-introducing treatment (Wc) (corresponds to average width of the magnetic domain discontinuous portion on the strain-introduced surface). Para. [0028]. The ratio of Wd/Wc is greater than 0.8 (abstract; para. [0011], [0028]), which encompasses the claimed ratio of 1.00 time or more.
Wc is less than 0.35 mm (less than 350 µm). Abstract; para. [0011], [0028]. Because the ratio of Wd/Wc is greater than 0.8, it follows that Wd can be 0.28 mm (280 µm) or higher or Wd can be a value lower than 0.28 mm lower if a Wc value less than 0.35 mm is selected. For example, if Wc is 0.25 mm (250 µm), then Wd is greater than 0.20 mm (200 µm), which overlaps the claimed range. In a specific example in Yamaguchi, Wd is 0.24 mm (240 µm) (Table 1 – ID #9), which falls within the claimed range.
Yamaguchi discloses that the steel sheet contains a forsterite film (para. [0047], [0050]), but does not specify its ratio on each side of the steel sheet.
Omura is directed to a grain oriented electrical steel sheet. Abstract; para. [0002], [0009]. The steel sheet has forsterite film on a strain-introduced side (strain-induced surface on one of the sides of the steel sheet) and a non-strain-introduced side. Para. [0010], [0029], [0030]. A ratio (Wa/Wb) of a film thickness of the forsterite film on a strain-introduced side of the steel sheet (Wa) to a film thickness of the forsterite film on a non-strain-introduced side of the steel sheet (Wb) is 0.5 or higher. Para. [0010], [0030].
The forsterite film on the surface of the steel sheet applies tension to the steel sheet, but a variation in the thickness the forsterite film causes that tension to be distributed non-uniformly. Para. [0030]. Non-uniform tension distribution results in a distortion in the magnetostrictive vibration waveform of the steel sheet, which causes an increase in undesirable noise. Para. [0030].
Therefore, it would have been obvious to one of ordinary skill in the art to have ensured that the forsterite film thickness in Yamaguchi is uniform on both sides of the steel, such as a thickness ratio of 0.5 or more, as taught by Omura, because this ensures an even distribution of tension and reduces noise in the steel sheet.
Yamaguchi is silent regarding a compressive stress existing in a rolling direction in a surface of the steel sheet.
Takajo is directed grain-oriented electrical steel sheet. Abstract; para. [0001], [0020]. Larger compressive strains in the rolling direction are preferred because they stabilize closure domains and enhances the magnetic domain refining effect. Para. [0035]. By controlling the distribution of tensile and compressive strains in the steel sheet, the grain-oriented electrical steel sheet exhibits extremely low iron loss and extremely low noise properties. Para. [0022], [0044].
Yamaguchi is concerned with the effect of reducing iron loss and noise. Para. [0014], [0017], [0018], [0020]. Therefore, it would have been obvious to one of ordinary skill in the art to have imposed a compressive stress in a rolling direction in the steel sheet of Yamaguchi because a compressive stress would enhance iron loss properties and decrease noise.
Takajo is silent regarding a depth of at least 2 µm of the compressive stress in the steel sheet in a thickness direction.
Kwon is directed to a method for producing a low core loss grain-oriented electrical steel sheet. Abstract; p. 2 – line 1. The sheet possesses a compressive strain layer on the surface, the depth and width of which are easily controlled. Page 4 – lines 14-19. The depth of the compressive residual stress zone is 1-30 µm (page 5 – lines 7-15; page 7 – lines 2-4), which overlaps the claimed range. This compressive stress at the surface maintains high magnetic density while exhibiting excellent iron loss characteristics, increases the stability of work, and minimizes the occurrence of surface defects in grain-oriented electrical steel sheets. Page 5 – lines 15-20.
Yamaguchi is concerned with the effect of reducing iron loss. Para. [0014], [0020]. Therefore, it would have been obvious to one of ordinary skill in the art to have ensured a compressive stress depth of between 1 µm and 30 µm, as taught by Kwon, in the steel sheet of Yamaguchi in view of Omura, because of iron loss properties would be further enhanced by such a structure.
Response to Arguments
Applicant's arguments filed 11/05/2025 have been fully considered.
Applicant’s arguments with respect to Omura have been considered but are moot in view of the new grounds of rejection, which relies on a new combination of prior art references.
With respect to Applicant’s position is that Omura teaches away from the claimed invention because Omura teaches that an average width of a magnetic domain discontinuous portion in a surface of the steel sheet on the non-strain-introduced side ranges from 250 µm to 500 µm, whereas the claimed invention recites an average width of less than 250 µm, such an argument is not persuasive because it isolates Omura individually and does not take into account the prior art teachings as a whole. See MPEP § 2145(IV).
Yamaguchi discloses that that the average width of magnetic domain discontinuous portion in the untreated surface (Wd) can take on a range of values. In a specific example, Yamaguchi discloses a Wd value of 0.24 mm (240 µm) (Table 1 – ID #9), which falls within the claimed range. Since an average width of a magnetic domain discontinuous portion resulting from the strain-introducing treatment (Wc) can be any value less than 0.35 mm (less than 350 µm) and Wd/Wc is greater than 0.8, it follows that Wd can be a variety of values, including those less than 0.25 mm (250 µm), depending on which Wc value is selected.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
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/VANESSA T. LUK/Primary Examiner, Art Unit 1733
April 14, 2026