Prosecution Insights
Last updated: April 19, 2026
Application No. 18/268,557

MARTENSITIC STAINLESS STEEL WITH IMPROVED STRENGTH AND CORROSION RESISTANCE, AND MANUFACTURING METHOD THEREFOR

Non-Final OA §103§112
Filed
Jun 20, 2023
Examiner
MOORE, ALEXANDRA MARIE
Art Unit
1738
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Posco Co. Ltd.
OA Round
1 (Non-Final)
64%
Grant Probability
Moderate
1-2
OA Rounds
3y 2m
To Grant
83%
With Interview

Examiner Intelligence

Grants 64% of resolved cases
64%
Career Allow Rate
298 granted / 467 resolved
-1.2% vs TC avg
Strong +19% interview lift
Without
With
+18.8%
Interview Lift
resolved cases with interview
Typical timeline
3y 2m
Avg Prosecution
40 currently pending
Career history
507
Total Applications
across all art units

Statute-Specific Performance

§101
0.5%
-39.5% vs TC avg
§103
46.0%
+6.0% vs TC avg
§102
17.5%
-22.5% vs TC avg
§112
28.3%
-11.7% vs TC avg
Black line = Tech Center average estimate • Based on career data from 467 resolved cases

Office Action

§103 §112
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 . Election/Restrictions Applicant’s election of Group I, claims 1-10, in the reply filed on 10/08/2025 is acknowledged. Because applicant did not distinctly and specifically point out the supposed errors in the restriction requirement, the election has been treated as an election without traverse (MPEP § 818.01(a)). Claims 11-20 are withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected invention, there being no allowable generic or linking claim. Election was made without traverse in the reply filed on 10/08/2025. Priority Receipt is acknowledged of certified copies of papers required by 37 CFR 1.55. Information Disclosure Statement The information disclosure statement (IDS) submitted 06/20/2023, 11/20/2024, and 07/16/2025 have been considered by the examiner. Claim Objections Claims 1-10 are objected to because of the following informalities: Claim 1 includes the word “reminder” which appears to be a typo of the intended word ‘remainder’. Appropriate correction is required. Claim Rejections - 35 USC § 112 The following is a quotation of 35 U.S.C. 112(b): (b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention. The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph: The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention. Claims 1-10 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention. Independent claim 1 includes “…with improved strength and corrosion resistance”. The term “improved” is a relative and/or subjective term which renders the claim indefinite. The term “improved” is not defined by the claim, the specification does not provide a standard for ascertaining the requisite degree, and one of ordinary skill in the art would not be reasonably apprised of the scope of the invention. The public and persons of ordinary skill in the art would not understand the scope of what “improved strength and corrosion resistance” is such that the they would be informed of the boundaries of what constitutes infringement of the patent. Claim 8 depends from claim 1 and further requires “…wherein a particle size of the primary carbide is 10 µm or less” which lacks sufficient antecedent basis because no carbides are recited in claim 1. However, it is noted that claim 5 introduces ‘a primary carbide’ while claim 6, which depends from claim 5, includes “the primary carbide”. Thus, it is unclear if claim 8 should depend from claim 5 or claim 6. In the interest of furthering prosecution, claim 8 has been interpreted to depend from claim 5. Claim Rejections - 35 USC § 103 In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. 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. The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows: 1. Determining the scope and contents of the prior art. 2. Ascertaining the differences between the prior art and the claims at issue. 3. Resolving the level of ordinary skill in the pertinent art. 4. Considering objective evidence present in the application indicating obviousness or nonobviousness. This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention. Claims 1-10 are rejected under 35 U.S.C. 103 as being unpatentable over Millward et al. (WO 2016/093762). Regarding claim 1, Millward et al. (Hereinafter “Millward”) teaches a stainless steel strip having a matrix comprising tempered martensite and austenite (meeting claimed ‘martensitic stainless steel’ because the steel includes tempered martensite) having a composition as follows: Element Claimed Millward Broad (Pgs 2-5) Millward Inv. Ex. Analysis of Inv. Ex C 0.3-0.5 0.3-0.5 0.40 Within range N 0.01-0.025 0.02-0.15 0.052 Reasonably close Si 0.3-0.5 0.2-0.8 0.42 Within range Mn 0.4-0.6 0.2-1.0 0.56 Within range Cr 13.1-14.5 12.0-15.0 13.4 Within range Mo 0.95-1.10 0.5-2.0 0.99 Within range V 0.05-0.3 0.01-0.20 0.055 Within range Ni 0.3-0.5 ≤ 2.0 0.15 Reasonably close Cu 0.001-0.5 ≤ 2.0 - Reasonably close Fe Remainder Remainder Remainder Within range impurities inevitable impurities impurities Within range To be clear, the broad ranges disclosed by Millward meet the claimed ranges while the inventive example of Millward is reasonably close to the claimed ranges. It has been held that a prima facie case of obviousness exists where the claimed ranges ‘overlap or lie inside ranges disclosed by the prior art’ In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976). Additionally, it has been held that ‘a prima facie case of obviousness exists where the claimed ranges or amounts do not overlap with the prior art but are merely close’. Titanium Metals Corp. of America v. Banner, 778 F.2d 775, 783, 227 USPQ 773, 779 (Fed. Cir. 1985). In the instant case, the proportion are so close that prima facie one skilled in the art would have expected them to have the same properties. With regard to the claimed feature directed to the composition satisfying claimed Formula (1), using the minimum and maximum values of the broadly disclosed ranges, Millward effectively embodies a minimum value of 7.12 and a maximum value of 52.8 when calculated according to claimed Formula 1. Thus, the effectively disclosed range of Millward is 7.12 to 52.8 which overlaps the claimed range of 16.4 to 23.3. As an additionally finding of fact, the inventive example of Millward embodies a value of 18.28 which lies squarely within the claimed range of 16.4 to 23.3. Lastly, and considering the language of the preamble directed to the martensitic stainless steel sheet being ‘hot-rolled annealed’ and having improved strength and corrosion resistance, it is noted that ‘hot-rolled annealed’ is product by process language (MPEP 2113) and Millward expressly teaches that the steel strip is improved (Page 2 line 11) and has an optimized property profile (Page 2 line 4) as well as “improved” properties (Page 7 line 20). Specifically, Millward teaches that chromium is added to impart corrosion resistance to the steel (Page 3 lines 12-13). “[E]ven though product-by-process claims are limited by and defined by the process, determination of patentability is based on the product itself. The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process” In re Thorpe, 777 F.2d 695, 698, 227 USPQ 964, 966 (Fed. Cir. 1985) (MPEP 2113). Thus, there is sufficient prima facie basis to expect that Millward’s martensitic stainless steel sheet, even though it is manufactured by cold-rolling (see Page 2 line 14; i.e. a different process than ‘hot-rolled annealed’ as claimed), would embody improved strength and corrosion resistance absent evidence to the contrary. Regarding claim 2, Millward teaches the composition as applied to claim 1 above but is silent to the composition satisfying claimed Formula (2). However, the composition of Millward is reasonably close such that, using the inventive example of Millward and approximating that Fe comprises 83.9534% of the composition and 0.001% Cu is present as an impurity (supported at least by Page 4 lines 23-28 “Cu may contribute to increasing the hardness and the corrosion resistance of the steel” and “Copper (≤ 2.0%)”), the inventive example meets the claimed Formula (2) because, when calculated, the example would embody a value of approximately 38.51 which lies within the claimed range of -14 to 50. To make the record clear, the Ni % in the inventive example is 0.15% which lies slightly outside of the claimed range of 0.3 to 0.5% but, using this value in the calculation, the composition still achieves a value within claimed Formula 2. Notably, the difference between 0.15 and the lower bound of 0.3 is 0.15%, which without evidence that such a difference is significant or critical, would be considered to be ‘reasonably close’ to the claimed lower bound. Nevertheless, the broad range for nickel (i.e. “≤ 2.0%” at Page 4 lines 8-12) disclosed by Millward meets the claimed range. Regarding claim 3, Millward teaches the composition as applied to claim 1 above but is silent to the composition satisfying claimed Formula (3). However, using the disclosed broad ranges of C and N taught by Millward, the composition embodies a minimum value of 0.32 (i.e., 0.3 + 0.02) and a maximum value of 0.65 (i.e. 0.5 + 0.15) which overlaps the claimed range of 0.37 to 0.43. Regarding claim 4, Millward teaches the composition as applied to claim 1 above but is silent to the composition satisfying claimed Formula (4). However, using the disclosed broad ranges of Mo and V taught by Millward, the composition embodies a minimum value of 0.51 (i.e., 0.5 + 0.01) and a maximum value of 2.2 (i.e. 2.0+ 0.20) which overlaps the claimed range of 1.0 to 1.35. Regarding claim 5, Millward teaches the composition as applied to claim 1 above but is silent to the composition having a ferrite as a base structure; a primary carbide represented by (Cr, Fe, Mo, V)7C3; and a secondary carbide represented by (Cr, Fe, Mo, V)23C6. However, Millward acknowledges that C forms primary carbides of the type M23C6, M7C3, and M6C (Pg 2 lines 27-33; but that the steel limits these carbides with preferably none present), Si is a strong ferrite former and increases carbon activity (Pg 2 lines 35-37), Cr and Mo are ferrite stabilizers with Mo expressly being a “strong carbide forming element and also a strong ferrite former”, and V forms evenly distributed fine precipitated carbides in the matrix (Page 3 lines 11-31). USPTO does not possess the capabilities to make and test compositions of the prior art. Considering that Millward teaches a composition that meets the claimed composition and expressly describes that elements present in the composition would form primary carbide, fine precipitated carbides (i.e. secondary carbides), and ferrite, there is a sufficient prima facie basis to expect the composition of Millward to possess “a ferrite as a base structure; a primary carbide represented by (Cr, Fe, Mo, V)7C3; and a secondary carbide represented by (Cr, Fe, Mo, V)23C6” absent evidence to the contrary. It has been held that ‘where the claimed and prior art products are identical or substantially identical in structure or composition, or are produced by identical or substantially identical processes, a prima facie case of either anticipation or obviousness has been established. In re Best, 562 F.2d 1252, 1255, 195 USPQ 430, 433 (CCPA 1977). Additionally, it has been held that ‘[p]roducts of identical chemical composition cannot have mutually exclusive properties’. In re Spada, 911 F.2d 705, 709, 15 USPQ 2d 1655, 1658 (Fed. Cir. 1998). Further, it has been held that ‘when the reference discloses all the limitations of a claim except a property or function, and the examiner cannot determine whether or not the reference inherently possesses properties which anticipate or render obvious the claimed invention but has basis for shifting the burden of proof to applicant as in In re Fitzgerald, 619 F. 2d 67, 205 USPQ 594, (CCPA 1980). Lastly, it has been held that ‘when the PTO shows a sound basis for believing that the products of the applicant and the prior art are the same, the applicant has the burden of showing that they are not’. In re Spada, 911 F.2d 705, 709, 15 USPQ2d 1655, 1658 (Fed. Cir. 1990) and it’s fairness is evidenced by the PTO’s inability to manufacture products or to obtain and compare prior art products See In re Brown, 459 F.2d 531, 59 CCPA 1036, 173 USPQ 685 (1972). Regarding claims 6 and 7, Millward teaches the composition as applied to claim 5 above but is silent to the wt% of (Mo+V) in the primary and secondary carbides being from 2.93 to 5.67% and 12.2 to 14.8%, respectively. However, it has been held that ‘where the claimed and prior art products are identical or substantially identical in structure or composition, or are produced by identical or substantially identical processes, a prima facie case of either anticipation or obviousness has been established. In re Best, 562 F.2d 1252, 1255, 195 USPQ 430, 433 (CCPA 1977). Additionally, it has been held that ‘[p]roducts of identical chemical composition cannot have mutually exclusive properties’. In re Spada, 911 F.2d 705, 709, 15 USPQ 2d 1655, 1658 (Fed. Cir. 1998). Further, it has been held that ‘when the reference discloses all the limitations of a claim except a property or function, and the examiner cannot determine whether or not the reference inherently possesses properties which anticipate or render obvious the claimed invention but has basis for shifting the burden of proof to applicant as in In re Fitzgerald, 619 F. 2d 67, 205 USPQ 594, (CCPA 1980). Lastly, it has been held that ‘when the PTO shows a sound basis for believing that the products of the applicant and the prior art are the same, the applicant has the burden of showing that they are not’. In re Spada, 911 F.2d 705, 709, 15 USPQ2d 1655, 1658 (Fed. Cir. 1990) and it’s fairness is evidenced by the PTO’s inability to manufacture products or to obtain and compare prior art products See In re Brown, 459 F.2d 531, 59 CCPA 1036, 173 USPQ 685 (1972). In the instant case, Millward acknowledges that C forms primary carbides of the type M23C6, M7C3, and M6C (Pg 2 lines 27-33; but that the steel limits these carbides with preferably none present), Si is a strong ferrite former and increases carbon activity (Pg 2 lines 35-37), Cr and Mo are ferrite stabilizers with Mo expressly being a “strong carbide forming element and also a strong ferrite former”, and V forms evenly distributed fine precipitated carbides in the matrix (Page 3 lines 11-31). USPTO does not possess the capabilities to make and test compositions of the prior art. Considering that Millward teaches a composition that meets the claimed composition and expressly describes that elements present in the composition would form primary carbide, fine precipitated carbides (i.e. secondary carbides), and ferrite, there is a sufficient prima facie basis to expect the composition of Millward to possess a wt% of (Mo+V) in the primary and secondary carbides from 2.93 to 5.67% and 12.2 to 14.8%, respectively. Regarding claims 8-10, Millward teaches the composition as applied to claim 1 and/or 5 above but is silent to the particle size of the primary carbide being 10 micron or less, a carbide deviation is 10 pieces/100 square microns or less in a longitudinal direction, and/or after being cold-rolled, a distribution density of carbide is 42 to 58 pieces/100 square microns. However, it has been held that ‘where the claimed and prior art products are identical or substantially identical in structure or composition, or are produced by identical or substantially identical processes, a prima facie case of either anticipation or obviousness has been established. In re Best, 562 F.2d 1252, 1255, 195 USPQ 430, 433 (CCPA 1977). Additionally, it has been held that ‘[p]roducts of identical chemical composition cannot have mutually exclusive properties’. In re Spada, 911 F.2d 705, 709, 15 USPQ 2d 1655, 1658 (Fed. Cir. 1998). Further, it has been held that ‘when the reference discloses all the limitations of a claim except a property or function, and the examiner cannot determine whether or not the reference inherently possesses properties which anticipate or render obvious the claimed invention but has basis for shifting the burden of proof to applicant as in In re Fitzgerald, 619 F. 2d 67, 205 USPQ 594, (CCPA 1980). Lastly, it has been held that ‘when the PTO shows a sound basis for believing that the products of the applicant and the prior art are the same, the applicant has the burden of showing that they are not’. In re Spada, 911 F.2d 705, 709, 15 USPQ2d 1655, 1658 (Fed. Cir. 1990) and it’s fairness is evidenced by the PTO’s inability to manufacture products or to obtain and compare prior art products See In re Brown, 459 F.2d 531, 59 CCPA 1036, 173 USPQ 685 (1972). Considering that Millward teaches a composition that meets the claimed composition, there is a sufficient prima facie basis to expect that the composition of Millward would possess the features as claimed and/or perform in the manner claimed (i.e. ‘after cold-rolled, a distribution density of carbide is 42 to 58 pieces/100 µm2’) absent evidence to the contrary. Conclusion The prior art made of record and not relied upon is considered pertinent to applicant's disclosure: Ohtsubo et al. (U.S. 5,939,018) directed to a martensitic stainless steel for a seamless steel pipe with similar composition to that claimed (see Col. 5 for various recitations/disclosures regarding elemental composition and effects). Any inquiry concerning this communication or earlier communications from the examiner should be directed to ALEXANDRA M MOORE whose telephone number is (571)272-8502. The examiner can normally be reached M-F 8am-5pm, EST. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Sally Merkling can be reached at 571-272-6297. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. ALEXANDRA M MOORE Primary Examiner Art Unit 1738 /ALEXANDRA M MOORE/Primary Examiner, Art Unit 1738
Read full office action

Prosecution Timeline

Jun 20, 2023
Application Filed
Dec 23, 2025
Non-Final Rejection — §103, §112 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

1-2
Expected OA Rounds
64%
Grant Probability
83%
With Interview (+18.8%)
3y 2m
Median Time to Grant
Low
PTA Risk
Based on 467 resolved cases by this examiner. Grant probability derived from career allow rate.

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