DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 10/8/25 has been entered.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claim 1 is rejected under 35 U.S.C. 103 as being unpatentable over Ishimaru (WO 2016/076254-A1, “Ishimaru”, of record) in view of Yoshimi et al. (WO 2019/138869 A1, hereafter “Yoshimi”, see attached document).
Regarding claim 1, Ishimaru discloses a corrosion-resistant austenitic stainless steel consisting of compositions relative to that of the instant claims as set forth below (abstract, [0014-0032], table 1 samples):
Instant claim 1
Prior art
Element
mass%
WO 2016/076254
Overlap
C
0.005-0.03
<=0.1 [0014]
0.005-0.03
Si
0.05-0.3
<=0.5 [0015]
0.05-0.3
Mn
0.05-0.4
<=0.5 [0016]
0.05-0.4
P
0.005-0.05
<=0.05 [0017]
0.005-0.05
S
0.0001-0.001
<=0.002 [0018]
0.0001-0.001
Ni
22-32
20-37 [0019]
22-32
Cr
19-28
18-28 [0020]
19-28
Mo
5 to 7
4 to 7 [0021]
5 to 7
N
0.18-0.25
0.2-0.3 [0023]
0.20-0.25
Al
0.005-0.1
0.005-0.05 [0024]
0.005-0.05
Cu
0.05-0.5
0.5-2.0 [0022]
0.5
Co
0.03-0.3
-
-
Sn
0.0005-0.015
0.001-0.50 [0028]
0.001-0.015
B
0.0005-0.005
0.002 [0027]
0.002
W
<=0.05
0.01-1.0 [0028]
0.01
Fe
balance
balance
balance
As seen in the table above, the amounts of respective elements in the austenitic stainless steel taught by Ishimaru overlap with recited amounts. Concerning formula (1), using exemplary amounts of B (0.002), P (0.026), Sn (0.001) and Si (0.26) (sample no. 25-27), this results in a value of about 0.086, which falls within the claimed range. Ishimaru teaches an area ratio of a sigma phase (σ) being less than 1% ([0045], Table 2A- column 8) and CPT as corrosion resistance property being greater than 60 °C ([0047, (Table 2A- column 6). These values meet the claimed ranges. In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990), MPEP 2144.05. Accordingly, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to select claimed amounts of carbon, silicon, manganese, phosphorus, sulfur, nickel, chromium, molybdenum, nitrogen, aluminum, tungsten, tin, boron and iron elements in the austenitic stainless steel from the amounts disclosed by Ishimaru because Ishimaru teaches the same purpose of obtaining excellent corrosion resistance in the disclosed ranges and utility in corrosive environments such as chemical plants or marine applications [0001, 0038, 0039].
Ishimaru discloses 0.5% copper (close to 0.4%) and lacks cobalt. However, adding such constituents are known in the stainless steel art. Yoshimi (also directed to austenitic stainless steel alloy composition- abstract) teaches method of manufacturing an austenitic stainless steel used in a corrosive environment such as marine environment or a chemical plant (technical field). Specifically, Yoshimi teaches adding copper (Cu) for improving corrosion resistance [0026], wherein the amount Cu is 3.0% or less, with preferable lower limits 0.10% or 0.30% [0028], which overlaps with claimed range of 0.05-0.40%. Although Ishimaru mentions reduced effect of corrosion resistance below 0.5% Cu, this weakness is remedied by Yoshimi, which teaches that corrosion resistance is still improved by 0.30 mass% copper. Yoshimi also teaches adding cobalt (Co) for improving corrosion resistance [0037], wherein the amount of Co is within 0.001-0.5% with preferable range of 0.01-0.3% [0039], which overlaps with claimed range of 0.01-0.3%. In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists, MPEP 2144.05.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to incorporate about 0.1-0.3% Co and Cu in the austenite stainless steel composition of Ishimaru because doing so would stabilize the austenite phase and improve corrosion resistance, as suggested by Yoshimi.
Claim 2 is rejected under 35 U.S.C. 103 as being unpatentable over Ishimaru (WO 2016/076254-A1) in view of Yoshimi et al. (WO 2019/138869 A1, see attached document), and further in view of Ueyama (US 9506126).
Regarding claim 2, rejection of claim 1 above is incorporated herein. Ishimaru discloses the austenitic stainless steel further including V in amount of 0.01-0.50% [0031] and Nb in amount of 0.001-0.4% [0028], which overlaps with claimed ranges and satisfy the formula. Concerning formula (2), using exemplary amounts of V (0.05), Nb (0.05), B (0.002), N (0.25), C (0.01) and Mn (0.33) (sample no. 25-27), this results in a value of about 4.81, which falls within the claimed range.
Ishimaru fails to disclose crystal grain size, based on JIS standard, in a range of 3-7 in the steel composition. However, such size is known in the steel art. Ueyama (also drawn to method for producing austenitic stainless steel- technical field) discloses area fraction of the sigma phase being at most 0.1 %, which is analogous to stainless steel of Ishimaru, and a crystal grain size, based on JIS G0551, being at least 6.0 (col. 2, lines 8-21)- this meets the claimed range of 3-7. Ueyama teaches that this grain size produces excellent high temperature strength while maintaining nitic acid corrosion resistance (col. 5, lines 16-23; Table 2). Consequently, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to provide crystal grain size of 6.0 in the austenitic stainless steel of Ishimaru because it would result in excellent high temperature strength while maintaining desired high corrosion resistance, as suggested by Ueyama.
Claims 3-4 are rejected under 35 U.S.C. 103 as being unpatentable over Ishimaru in view of Yoshimi OR Ishimaru, Yoshimi & Ueyama as applied above, and further in view of Kawamori et al. (CN 104919072-A, of record).
As to claims 3-4, Ishimaru teaches a method of manufacturing the austenitic stainless steel by the steps of melting, casting, hot rolling annealing, cold rolling and annealing with no particular restrictions on the equipment [0040]; the disclosure is silent in terms of solution heat treatment and holding temperature. However, such step is known in the art. In order to eliminate precipitate (sigma phase) harmful to the mechanical properties of the stainless steel alloy, Kawamori teaches a manufacturing method of stainless steel comprising applying solution heat treatment and quenching according to the need, preferably at temperature of 1000 °C and holding time of about 10-30 minutes [0099]. This meets the recited temperature treatment. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to perform claimed temperature holding for 10-30 minutes after solution heat treatment in the method of Ishimaru with the motivation to eliminate sigma phase (σ) precipitate harmful to the mechanical properties of the stainless steel.
Response to Amendment and Arguments
Applicant’s recent amendment and arguments against prior art with respect to amended claim(s) 1-2 have been considered but are moot in light new grounds of rejection(s) set forth above. The current 103 rejection(s) relies on teachings of Yoshimi and addresses the matter (copper & cobalt amount) challenged in the arguments.
Inquiry
Any inquiry concerning this communication or earlier communications from the examiner should be directed to DEVANG R PATEL whose telephone number is (571) 270-3636. The examiner can normally be reached on Monday-Friday 8am-5pm, EST.
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/DEVANG R PATEL/
Primary Examiner, AU 1735