One Case a Day | China: "Austenitic Stainless Steel" Patent Receives Final Judgment - (2023) Supreme People's Court Zhixing Zhong No. 1164

Case Introduction
Today's shared case is a judgment document published by the Supreme People's Court on November 13, 2025. In fact, the case was heard in court on April 25, 2024, and the Supreme People's Court reported on the trial in a press release, indicating the importance of this case. Today, the full text of the judgment is attached, and I will share my interpretation of this case on other platforms later. Please stay tuned.

One Case a Day | IP

Supreme People's Court of the People's Republic of China

Administrative Judgment

(2023) Supreme People's Court Zhixing Zhong No. 1164

Appellant (First-Instance Defendant): National Intellectual Property Administration. Domicile: No. 6 Xitucheng Road, Jimen Bridge, Haidian District, Beijing, People's Republic of China.

Legal Representative: Shen Changyu.

Authorized Litigation Agents: Liu Tong, Examiner of the Administration.
Cheng Qiang, Examiner of the Administration.

Appellant (First-Instance Third Party, Patentee): A Japanese Corporation. Domicile: Tokyo, Japan.

Representative: A certain Zuo, Representative Director of the Corporation.

Authorized Litigation Agents: Dong Huifang, Lawyer of Beijing Yongxin Intellectual Property Law Firm.
Zhang Chao, Lawyer of Beijing Yongxin Intellectual Property Law Firm.

Appellee (First-Instance Plaintiff, Invalidation Requester): A Certain Stainless Steel Pipe Company. Domicile: Alcarava Province, Kingdom of Spain.

Representative: A certain He, Sole Shareholder Director of the Company.

Authorized Litigation Agents: Zhang Hao, Lawyer of Beijing Unitalen Attorneys at Law.
Yu Feifan, Lawyer of Beijing Unitalen Attorneys at Law.

This case involves an administrative dispute over the invalidation of an invention patent between the appellant National Intellectual Property Administration, the appellant A Japanese Corporation, and the appellee A Certain Stainless Steel Pipe Company. The patent involved is titled "Austenitic Stainless Steel Pipe with Excellent Water Vapor Oxidation Resistance and Its Manufacturing Method" (hereinafter referred to as "this patent"), with the patentee being A Japanese Corporation. In response to the invalidation request filed by A Certain Stainless Steel Pipe Company against this patent, the National Intellectual Property Administration made the Invalidation Request Examination Decision No. 54147 (hereinafter referred to as the "challenged decision"), continuing to maintain the validity of this patent based on the amended claims 1-10 submitted by A Japanese Corporation on November 18, 2021. Dissatisfied with this, A Certain Stainless Steel Pipe Company filed a lawsuit with the Beijing Intellectual Property Court (hereinafter referred to as the "first-instance court"), requesting the revocation of the challenged decision and ordering the National Intellectual Property Administration to reissue an examination decision. The first-instance court rendered the administrative judgment (2022) Jing 73 Xing Chu No. 13589 (hereinafter referred to as the "first-instance judgment") on September 20, 2023, revoking the challenged decision and ordering the National Intellectual Property Administration to reissue an examination decision. Dissatisfied with this, both the National Intellectual Property Administration and A Certain Stainless Steel Pipe Company appealed to this court. This court accepted the case on December 12, 2023, formed a collegial panel according to law, and held a public hearing on April 25, 2024. The authorized litigation agents Liu Tong and Cheng Qiang of the appellant National Intellectual Property Administration, the authorized litigation agents Dong Huifang and Zhang Chao of the appellant A Japanese Corporation, and the authorized litigation agents Zhang Hao and Yu Feifan of the appellee A Certain Stainless Steel Pipe Company appeared in court to participate in the proceedings. The case is now concluded.

The basic facts of this case are as follows:

This patent is an invention patent titled "Austenitic Stainless Steel Pipe with Excellent Water Vapor Oxidation Resistance and Its Manufacturing Method," with the patentee being A Japanese Corporation. The application date is March 10, 2003, the priority date is March 8, 2002, and the authorization announcement date is September 28, 2005. A Japanese Corporation submitted replacement pages for the amended claims on November 18, 2021, with a total of 10 amended claims. The amended claims 1-10 of this patent as of November 18, 2021, serving as the examination basis for this case, are as follows:

"1. An austenitic stainless steel pipe with excellent water vapor oxidation resistance, characterized in that the steel pipe contains, by mass %, C: 0.03-0.12%, Si: 0.1-0.9%, Mn: 0.1-2%, Cr: 15-22%, Ni: 8-15%, Ti: 0.002-0.05%, Nb: 0.3-1.5%, sol. Al: 0.0005-0.03%, N: 0.005-0.2%, and O: more than 0.001% but less than 0.005%, with the remainder consisting of Fe and impurities, and having a fine-grained structure with an austenite grain size number of 7 or higher.

2. The austenitic stainless steel pipe with excellent water vapor oxidation resistance according to claim 1, characterized in that it further contains, by mass %, at least one component selected from the following Group 1 and Group 2, either one group or both groups:
Group 1: Ca, Mg, Zr, B, Pd, Hf, and REM, each in an amount of 0.0001-0.2% by mass;
Group 2: Cu, Mo, and W, each in an amount of 0.01-5% by mass.

3. The austenitic stainless steel pipe with excellent water vapor oxidation resistance according to claim 1, characterized in that it has a fine-grained structure with an austenite grain size number of 7 or higher, and the mixed grain rate of austenite grains is 10% or less.

4. The austenitic stainless steel pipe with excellent water vapor oxidation resistance according to claim 1, characterized in that it further contains, by mass %, at least one component selected from the following Group 1 and Group 2, either one group or both groups, and has a fine-grained structure with an austenite grain size number of 7 or higher, and the mixed grain rate of austenite grains is 10% or less:
Group 1: Ca, Mg, Zr, B, Pd, Hf, and REM, each in an amount of 0.0001-0.2% by mass;
Group 2: Cu, Mo, and W, each in an amount of 0.01-5% by mass.

5. An austenitic stainless steel pipe with excellent water vapor oxidation resistance, characterized in that the steel pipe contains, by mass %, C: 0.03-0.12%, Si: 0.1-0.9%, Mn: 0.1-2%, Cr: 15-22%, Ni: 8-15%, Ti: 0.002-0.05%, Nb: 0.3-1.5%, sol. Al: 0.0005-0.03%, N: 0.005-0.2%, and O: 0.001-0.008%, with the remainder consisting of Fe and impurities, and having a fine-grained structure with an austenite grain size number of 7 or higher, and the mixed grain rate of austenite grains is 10% or less.

6.An austenitic stainless steel pipe with excellent water vapor oxidation resistance, characterized in that the steel pipe contains, by mass %, C: 0.03-0.12%, Si: 0.1-0.9%, Mn: 0.1-2%, Cr: 15-22%, Ni: 5-15%, Ti: 0.002-0.05%, Nb: 0.3-1.5%, sol. Al: 0.0005-0.03%, N: 0.005-0.2%, and O: 0.001-0.008%, with the remainder consisting of Fe and impurities,
and further contains, by mass %, at least one component selected from the following Group 1 and Group 2, either one group or both groups, and has a fine-grained structure with an austenite grain size number of 7 or higher, and the mixed grain rate of austenite grains is 10% or less;
Group 1: Ca, Mg, Zr, B, Pd, Hf, and REM, each in an amount of 0.0001-0.2% by mass;
Group 2: Cu, Mo, and W, each in an amount of 0.01-5% by mass.

7.A method for manufacturing an austenitic stainless steel pipe with excellent water vapor oxidation resistance, characterized in that for an austenitic stainless steel pipe containing, by mass %, C: 0.03-0.12%, Si: 0.1-0.9%, Mn: 0.1-2%, Cr: 15-22%, Ni: 8-15%, Ti: 0.002-0.05%, Nb: 0.3-1.5%, sol. Al: 0.0005-0.03%, N: 0.005-0.2%, O: 0.0001-0.008%, with the remainder consisting of Fe and impurities; or an austenitic stainless steel pipe that, in addition to the above components, further contains at least one component selected from the following Group 1 and Group 2, either one group or both groups, the following processes ①, ②, and ③ are sequentially performed:
Group 1: Ca, Mg, Zr, B, Pd, Hf, and REM, each in an amount of 0.0001-0.2% by mass;
Group 2: Cu, Mo, and W, each in an amount of 0.01-5% by mass;
Process ①: Heating and holding at 1100-1350°C, followed by cooling at a cooling rate of 0.25°C/second or higher;
Process ②: Performing plastic deformation with a cross-sectional reduction rate of 10% or more in a temperature region of 500°C or lower;
Process ③: Heating and holding within a temperature range of 1050-1300°C and at a temperature at least 10°C lower than the heating temperature in said process ①, followed by cooling.

8.The method for manufacturing an austenitic stainless steel pipe with excellent water vapor oxidation resistance according to claim 7, wherein the O content of the raw material austenitic stainless steel pipe is 0.001 mass% or more but less than 0.005 mass%.

9.The method for manufacturing an austenitic stainless steel pipe with excellent water vapor oxidation resistance according to claim 8, characterized in that in process ①, after heating the raw material steel to 1100-1350°C, it is formed into a steel pipe through hot working, and then the formed steel pipe is cooled at a cooling rate of 0.25°C/second or higher.

10.The method for manufacturing an austenitic stainless steel pipe with excellent water vapor oxidation resistance according to claim 9, wherein the O content of the raw material austenitic stainless steel pipe is 0.001 mass% or more but less than 0.005 mass%."

The description of this patent regarding the content of the invention states: "Furthermore, the so-called mixed grain rate (%) of austenite grains is a value defined by the formula {(n/N) × 100}, where N is the number of fields of view observed when determining the above-mentioned austenite grain size number using an optical microscope, and n is the number of fields of view judged as mixed grains where particles exist whose grain size number differs by about 3 or more from the particle with the maximum frequency, and these particles occupy about 20% or more of the area."

The description of this patent regarding the specific implementation method records two methods for manufacturing this patent, stating: "Then, cool the steel pipe heated in the first method or the steel pipe formed in the second method. At this time, if the cooling rate from 800°C to 500°C is lower than 0.25°C/second, coarse Nb carbonitrides or Cr carbonitrides will precipitate during cooling, preventing the generation of finely dispersed Nb composite carbonitrides, which is the purpose of this invention, and thus the desired fine-grained structure cannot be obtained." Subsequently, two examples are recorded. Example 1 involves melting 20 types of steel with different chemical compositions and processing the obtained steel ingots into plates according to manufacturing method A (the second method). However, the processing conditions correspond to the manufacturing conditions for steel pipes when using the first method. Example 2 involves processing the plates after process 2 of manufacturing method A in Example 1.

On August 12, 2021, A Certain Stainless Steel Pipe Company requested the National Intellectual Property Administration to declare this patent entirely invalid. During the oral hearing in the invalidation procedure, A Certain Stainless Steel Pipe Company clarified its invalidation grounds as: using Evidence 1, Evidence 2, or Evidence 3 respectively as the closest prior art, the amended claims 1-10 of this patent do not possess inventiveness as stipulated in Article 22, Paragraph 3 of the Patent Law of the People's Republic of China (2000 Amendment) (hereinafter referred to as the "Patent Law"); the description does not comply with the provisions of Article 26, Paragraph 3 of the Patent Law, involving the technical solutions of claims 3-6.

Some of the evidence submitted by A Certain Stainless Steel Pipe Company is as follows:

Evidence 1: Patent document JP Hei 7-258801 A and its Chinese translation, published on October 9, 1995. Evidence 1 discloses an Fe-Cr-Ni series alloy with excellent corrosion resistance and workability [see Table 1 (Part 1)], wherein alloy No. 15 has the composition: C 487 ppm, N 353 ppm, Si 0.45%, Mn 1.4%, Cr 18.2%, Ni 8.5%, Ti 0.02%, Al 0.004%, O 24 ppm, grain size 11; alloy No. 17 has the composition: C 522 ppm, N 387 ppm, Si 0.45%, Mn 1.4%, Cr 18.2%, Ni 8.3%, Ti 0.02%, Al 0.004%, O 24 ppm, Cu 0.3%, grain size 8.

Evidence 2: Patent document JP Hei 10-72644 A and its Chinese translation, published on March 17, 1998. Evidence 2 discloses an austenitic stainless steel cold-rolled steel sheet (see claim 3), containing C: 0.01-0.11 wt%, Si: 0.05-3.0 wt%, Mn: 0.05-2.0 wt%, P: 0.04 wt% or less, S: 0.03 wt% or less, Al: 0.1 wt% or less, Cr: 15-25 wt%, Ni: 5-15 wt%, N: 0.005-0.3 wt%, O: 0.007 wt% or less, and containing at least one selected from Cu: 0.05-5.0 wt%, Co: 0.05-5.0 wt%, Mo: 0.05-5.0 wt%, W: 0.05-5.0 wt%, Ti: 0.01-0.5 wt%, Nb: 0.01-0.5 wt%, V: 0.01-0.5 wt%, Zr: 0.01-0.5 wt%, REM: 0.001-0.1 wt%, Y: 0.001-0.5 wt%, B: 0.0003-0.01 wt%, and Ca: 0.0003-0.01 wt%, with the remainder consisting of Fe and unavoidable impurities.

Evidence 3: Patent document JP Hei 9-310157 A and its Chinese translation, published on December 2, 1997. Evidence 3 discloses an austenitic stainless steel hot-rolled steel sheet with excellent deep drawability (see paragraph 11 of the description), characterized by containing C: 0.005-0.1 wt%, Si: 0.05-1.0 wt%, Mn: 0.05-2.0 wt%, P: 0.02 wt% or less, S: 0.03 wt% or less, Al: 0.005 wt% or less, Cr: 15-25 wt%, Ni: 5-15 wt%, N: 0.005-0.3 wt%, O: 0.01 wt% or less, and containing at least one selected from the group of Cu: 0.05-5.0 wt% and Co: 0.05-5.0 wt%, the group of Mo: 0.05-5.0 wt% and W: 0.05-5.0 wt%, the group of Ti: 0.01-0.5 wt%, Nb: 0.01-0.5 wt%, V: 0.01-0.5 wt%, and Zr: 0.01-0.5 wt%, and the group of B: 0.0003-0.01 wt% and Ca: 0.0003-0.01 wt%, with the remainder consisting of Fe and unavoidable impurities.

On February 11, 2022, the National Intellectual Property Administration issued the challenged decision, holding that: A Certain Stainless Steel Pipe Company's invalidation ground regarding insufficient disclosure of the technical solutions of claims 3-6 of this patent in the description could not be established. Regarding the invalidation ground that this patent lacks inventiveness, the stainless steel of this patent, through the specific content ratio of Nb, Ti, and O elements, uniformly disperses and generates composite precipitates with Ti2O3 as the core and Nb carbonitides precipitated around it, achieving corresponding technical effects. As the closest prior art, Evidence 1-3 do not simultaneously disclose the content ratio of Nb, Ti, and O elements in this patent, nor do they mention improving stainless steel performance by generating composite precipitates through the specific content ratio of the above three elements. A Certain Stainless Steel Pipe Company did not use other evidence to evaluate the content of Nb and Ti, so the challenged decision does not provide specific comments on the content of other evidence. Accordingly, the National Intellectual Property Administration decided: based on the amended claims 1-10 submitted by Nippon Steel Corporation on November 18, 2021, continue to maintain the validity of this patent.

Dissatisfied with this, A Certain Stainless Steel Pipe Company filed a lawsuit with the first-instance court on August 16, 2022, requesting: revocation of the challenged decision and ordering the National Intellectual Property Administration to reissue an examination decision. Facts and reasons: (1) The description of this patent is insufficiently disclosed, and the challenged decision also fails to clearly indicate the specific measurement and calculation method for the mixed grain rate; the challenged decision's factual determination is erroneous. (2) The challenged decision's determination regarding the inventiveness of this patent's claims is erroneous. 1. The challenged decision's process for determining inventiveness does not comply with the "three-step method" stipulated in the Patent Examination Guidelines. 2. The challenged decision's determination of distinguishing features is erroneous. 3. The challenged decision's determination of the technical problem to be solved by the distinguishing features is erroneous.

The National Intellectual Property Administration argued in the first instance: (1) Regarding insufficient disclosure, the description of this patent clearly records the calculation method for the mixed grain rate, and the grain size parameters involved therein are known parameters in this field, with their specific measurement methods being known to persons skilled in the art. (2) Regarding inventiveness, this patent clearly records that composite precipitates are formed through the coordinated content of Ti, Nb, and O to improve water vapor oxidation resistance, supported by examples. The comparison documents do not mention this technical concept, and the alloy element contents used are also conventional content ratios in the prior art, not disclosing the specific content ratios defined in this patent, which constitute distinguishing features. Therefore, this patent possesses inventiveness relative to the comparison documents. The litigation grounds of A Certain Stainless Steel Pipe Company cannot be established, and the court is requested to dismiss its claims.

A Japanese Corporation stated in the first instance: (1) The description of this patent is sufficiently disclosed and complies with the provisions of Article 26, Paragraph 3 of the Patent Law. (2) Claims 1-10 of this patent possess inventiveness. 1. The comparison documents provided by A Certain Stainless Steel Pipe Company do not disclose the specific content ratios of the three components Ti, Nb, and O. 2. Evidence 1-3 do not provide corresponding technical motivation, and persons skilled in the art have no motivation to adjust Evidence 1-3 to obtain this patent. (3) A Certain Stainless Steel Pipe Company, in the invalidation procedure, frequently conflated the overall content of comparison documents into a single technical solution, violating the rules for inventiveness determination. The court is requested to dismiss the claims of A Certain Stainless Steel Pipe Company.

The first-instance court, after trial, basically affirmed the above facts.

The first-instance court additionally found: On October 21, 2022, the National Intellectual Property Administration issued the Invalidation Request Examination Decision No. 58883 (hereinafter referred to as "Decision No. 58883") in response to an invalidation request filed by Salzgitter Mannesmann Stainless Tubes Italy S.p.A. against this patent. Decision No. 58883 shows that A Japanese Corporation amended the claims of this patent in that invalidation procedure on June 7, 2022, deleting the original claims 1 and 2 based on the claims maintained as valid by the challenged decision in this case, changing the original claims 3 and 4 to independent claims 1 and 2 respectively, and adaptively modifying the numbers and reference relationships of other claims. Decision No. 58883 determined that the amendments by A Japanese Corporation complied with the requirements for claim amendments under the Patent Law and the Implementing Regulations of the Patent Law of the People's Republic of China (2001 Revision) (hereinafter referred to as the "Implementing Regulations"). Decision No. 58883, based on the amended claims 1-8 this time, ultimately maintained the validity of this patent. A Japanese Corporation, A Certain Stainless Steel Pipe Company, and the National Intellectual Property Administration all acknowledged that Decision No. 58883 had not undergone administrative litigation and had already taken legal effect. During the first-instance trial of this case, A Certain Stainless Steel Pipe Company clearly stated that it had no objection to the examination basis determined by the challenged decision.

The first-instance court held:

Based on the ascertained facts, A Japanese Corporation, as the patentee, amended the claims in the patent invalidation procedure corresponding to the already effective Decision No. 58883, and Decision No. 58883 accepted this amendment. The amended claims 1-8 of this patent are substantially consistent in content with the pre-amendment claims 3-10. Furthermore, the commentary content of the challenged decision and the statements of the National Intellectual Property Administration during the first-instance trial can mutually corroborate. The challenged decision generally determined that the pre-amendment claims 1-10 all possess inventiveness. Under these circumstances, it is still possible to adjudicate whether the challenged decision's determination regarding the inventiveness of the pre-amendment claims 3-10 is lawful.

The challenged decision determined that Evidence 1-3 do not simultaneously disclose the content ratio of Nb, Ti, and O elements in this patent, nor do they mention improving stainless steel performance by generating composite precipitates through the specific content ratio of the above three elements, thereby determining that the pre-amendment claims 1-10 possess inventiveness. In this regard, first, according to the provisions of Article 56 of the Patent Law, the scope of protection for an invention or utility model patent is determined by the content of the claims, and the description and drawings can be used to interpret the claims. The claims of this patent only limit the content of C, Si, Mn, Cr, Ni, Ti, Nb, sol. Al, N, and O elements in the austenitic stainless steel pipe by mass %, and do not provide special explanation for the content ratio relationship of Nb, Ti, and O elements, nor do they limit generating composite precipitates through the specific content ratio of the above three elements. Second, even if, as recorded in the description of this patent, this patent improves stainless steel performance by generating composite precipitates, the description of this patent also records that cooling speed is also a factor in whether composite precipitates can be generated. Based on this, it can be seen that the challenged decision's determination conclusion that "composite precipitates are obtained through the specific content ratio of Nb, Ti, and O elements, achieving corresponding technical effects" is erroneous. In summary, the challenged decision's consideration of the content ratio of Nb, Ti, and O elements in the claims together to evaluate inventiveness lacks factual and legal basis and should be corrected. The National Intellectual Property Administration should re-evaluate the inventiveness of the claims based on a correct understanding of the claim content.

The first-instance court, in accordance with Items 1 and 2 of Article 70 of the Administrative Procedure Law of the People's Republic of China, ruled: "1. Revoke the Invalidation Request Examination Decision No. 54147 made by the defendant National Intellectual Property Administration; 2. The defendant National Intellectual Property Administration shall reissue an examination decision after this judgment takes effect. The case acceptance fee of RMB 100 shall be borne by the defendant National Intellectual Property Administration (to be paid within seven days after this judgment takes effect)."

The National Intellectual Property Administration, dissatisfied with the first-instance judgment, appealed to this court, requesting: revocation of the first-instance judgment and dismissal of the lawsuit of A Certain Stainless Steel Pipe Company. Facts and reasons: (1) Claim 1 of this patent has clearly limited the content of each element in the stainless steel and explained the addition effect of each element in the description, especially recording on pages 6-8 of the description that the content of Nb, Ti, and O elements is to obtain composite precipitates, thereby achieving technical effects different from the prior art. It can be seen that this patent has clearly recorded the synergistic effect of the above three elements. (2) Although the claims do not limit the addition effect and principle of each element, the description has sufficiently elaborated the specific role of each element's added content, especially the significant difference in the content ratio of Nb and Ti in claim 1, which the prior art does not particularly distinguish. Based on determining the distinguishing features, the challenged decision analyzed the addition effects of each element in the description and prior art evidence, especially their differences, to conclude that the invalidation ground of lack of inventiveness cannot be established. This conclusion is scientific and objective. (3) The claims limit the content range of each element, and the ratio relationship between them can be obtained through simple calculation. As for the explanation of "generating composite precipitates," it belongs to the technical effect of the invention, which has been explained in the description and does not need to be written in the claims. (4) Claim 1 is a product claim, usually characterized by the chemical composition of the product. Although claim 1 does not record the cooling speed, it still possesses inventiveness relative to the comparison documents.

A Japanese Corporation was also dissatisfied with the first-instance judgment and appealed to this court, requesting: revocation of the first-instance judgment and dismissal of the lawsuit of A Certain Stainless Steel Pipe Company. Facts and reasons: The first-instance court, in understanding the claims of this patent, omitted the important technical feature of "fine-grained structure with an austenite grain size number of 7 or higher" in the claims and did not consider how this feature is obtained as recorded in the description, thus failing to fully understand the correlation between this technical feature and "composite precipitates," ultimately leading to an erroneous determination on the issue of "composite precipitate" generation. Even if the challenged decision did not discuss the technical feature of "fine-grained structure with an austenite grain size number of 7 or higher" when determining the issue of "composite precipitate" generation, and its discussion was not comprehensive, given that the conclusion is correct, the lawsuit of A Certain Stainless Steel Pipe Company should be dismissed after correcting the relevant facts. Furthermore, this patent limits the magnitude relationship of Nb and Ti content, which also constitutes a distinguishing feature from the closest prior art. A Certain Stainless Steel Pipe Company did not provide any evidence to prove that this distinguishing feature has been disclosed.

A Certain Stainless Steel Pipe Company argued in response: The claims of this patent do not limit the content ratio of Nb, Ti, and O elements, nor do they define any Ti2O3 composite material, let alone composite precipitates. Therefore, the challenged decision's determination of the content ratio relationship of Nb, Ti, and O elements as distinguishing features constitutes a clear factual error. Even according to the description of this patent, cooling speed is also a factor in whether composite precipitates can be generated. Only by adopting specific production processes can the so-called composite precipitates be generated. The relevant composite precipitates are only disclosed in the description and not recited in the claims, and cannot become the basis for judging inventiveness. In Decision No. 58883, it was clearly determined that "composite precipitates" do not belong to the necessary technical features of the claims.

During the second instance of this case, none of the parties submitted new evidence, and all parties had no objection to the first-instance judgment's determination regarding the authenticity, legality, and relevance of the involved evidence.

This court, after trial, finds: The facts determined by the first-instance court are basically true, and this court confirms them.

This court additionally finds: The description of this patent regarding the background technology records: "Nb or Ti carbonitides are prone to re-dissolution during welding or high-temperature bending processing performed during boiler assembly construction, etc. Once re-dissolved, they lose their pinning effect, leading to abnormal grain growth, causing the fine-grained structure to disappear. That is to say, when using method (5), an austenitic stainless steel pipe with a homogeneous, complete-grained fine-grained structure that remains stable during construction cannot be obtained. ... It is well known in the field that for 18Cr-8Ni series austenitic stainless steel, there is a close relationship between grain size and water vapor oxidation resistance. The finer the grain steel, the more excellent the water vapor oxidation resistance it shows. If it is a fine grain with an austenite grain size number of 7 or higher as specified in ASTM (American Society for Testing and Materials), water vapor oxidation resistance can be improved." The description of this patent regarding the specific implementation method records: "(a) In Nb-containing steel with uniformly dispersed Ti2O3 precipitates, during heat treatment of the product, composite precipitates with Ti2O3 as the core and Nb carbonitides precipitated around it are uniformly dispersed and generated. (b) The above composite precipitates have the same fine-graining effect as Nb or Ti carbonitides. Therefore, by utilizing this, not only can a homogeneous, complete-grained fine-grained structure be stably obtained, but also because the composite precipitates are stable at high temperatures, they do not re-dissolve during welding or high-temperature bending processing in construction, thus maintaining the fine-grained structure.
(c) The above Ti2O3 can be generated by the following method: add an appropriate amount of Nb to molten steel that has been sufficiently refined to minimize inclusions such as Al2O3 or SiO2, then adjust the oxygen content of the steel to a suitable range (0.001-0.008 mass%), and then add Ti to contain an appropriate amount (0.002-0.005 mass%) of Ti. (d) Heat treat steel that has uniformly dispersed Ti2O3 generated by adding Ti and has an Nb content in a suitable range (0.3-1.5 mass%), and the above composite precipitates can be uniformly dispersed and generated. (e) Through final heat treatment, if a metal structure with an austenite grain size number of 7 or higher as specified in ASTM can be obtained, then water vapor oxidation resistance without thick water vapor oxidation scale can be ensured. Furthermore, when the mixed grain degree of this metal structure, calculated by the above mixed grain rate, is 10% or less, partial occurrence of strip-like water vapor oxidation scale does not appear, thereby further improving water vapor oxidation resistance. (f) The metal structure described in (e) above, according to conventional technology utilizing Nb or Ti carbonitides, must have the final heat treatment temperature at least 30°C lower than the heat treatment temperature of the previous stage to be obtained. However, for the steel of this invention, it can be obtained as long as the final heat treatment is performed at a temperature at least 10°C lower than the heat treatment temperature of the previous stage, and the obtained product has higher creep strength than products obtained by conventional technology. Below, the reasons for stipulating the conditions such as the chemical composition, grain size and mixed grain rate, and manufacturing method of the austenitic stainless steel pipe of this invention as described above are explained in detail. ... Ti: 0.002-0.05%. Ti, like O (oxygen) described below, is an indispensable element for uniformly dispersing and generating Ti2O3, which is the substance constituting the core of the composite precipitates, one of the important characteristics of the steel pipe of this invention. When its content is less than 0.002%, Ti2O3 cannot be generated, or even if generated, the amount uniformly dispersed is very small, and no effect is obtained. On the other hand, when its content exceeds 0.05%, coarse TiN is generated, hindering the fine dispersion and precipitation of Nb carbonitides, and composite precipitates with Ti2O3 as the core cannot be finely dispersed and generated. Therefore, the Ti content is set at 0.002-0.05%. Preferably, it is 0.002-0.03%. Nb: 0.3-1.5%. Nb is an indispensable element for generating the above composite precipitates, and the minimum necessary content is 0.3%. However, when contained in excess of 1.5%, significantly coarse precipitates are generated, impairing its strength. Therefore, the Nb content is set at 0.3-1.5%. Preferably, it is 0.4-1.3%.
... O (oxygen): 0.001-0.008%. O, like Ti above, is an indispensable element for uniformly dispersing and generating Ti2O3, which becomes the core of the above composite precipitates. When its content is less than 0.001%, Ti2O3 cannot be generated. On the other hand, when its content exceeds 0.008%, coarse oxides other than Ti2O3 are formed, significantly impairing steel quality, strength, and toughness. Therefore, the O content is set at 0.001-0.008%. Preferably: 0.001% or more, less than 0.005%. ... Then, cool the steel pipe heated in the first method or the steel pipe formed in the second method. At this time, if the cooling rate from 800°C to 500°C is lower than 0.25°C/second, coarse Nb carbonitides or Cr carbonitides will precipitate during cooling, preventing the generation of finely dispersed Nb composite carbonitides, which is the purpose of this invention, and thus the desired fine-grained structure cannot be obtained."

Evidence 1 description paragraph [0008] records: "As its mechanism, when O+P+S are low and C+N are also low, it is considered that a mechanism similar to secondary processing brittleness works. If decarburization and denitrification occur during annealing, the strength of the extreme surface layer decreases, making it easy to introduce fine defects in the processed part. On the other hand, it is considered that when C+N are excessive, solid solution and precipitation of carbonitides reduce workability, making it easy to generate defects in the processed part. This invention is based on the above insights." Paragraph [0009] records: "Total amount of O+P+S: The influence of O+P+S total amount and grain size on the corrosion resistance of processed and non-processed parts of SUS304 was investigated. As shown in the results in Figure 1, if the grain size number is 8 or higher, by reducing the O+P+S total amount to 200 ppm or less, the corrosion resistance of the processed part is also significantly improved. Therefore, in this invention, the O+P+S total amount is set to 200 ppm or less, preferably 160 ppm or less."

Evidence 2 description paragraph [0005] records: "The purpose of this invention is to provide an austenitic stainless steel cold-rolled steel sheet with small springback after press forming such as bending and stretching without excessively increasing grain diameter, and its manufacturing method. Another purpose of this invention is to provide an austenitic stainless steel cold-rolled steel sheet with fine grains of grain size number 6 or higher and small springback after press forming, even when the P amount is in a relatively high range such as 0.04 wt% or less." Paragraph [0008] records: "Therefore, the inventors of this invention further conducted repeated research on manufacturing technology to economically increase the accumulation degree of {200} texture parallel to the rolling surface after cold rolling and final annealing, without reducing the P amount to 0.015 wt% or less. As a result, as shown in the example of SUS304 in Figure 1, it was found that even when the P amount is a relatively high content such as 0.04 wt% or less, if the accumulation degree of {111} texture parallel to the rolling surface of the material before cold rolling (hot-rolled sheet) is 2.2 or higher, the accumulation degree of {200} texture parallel to the rolling surface after cold rolling and final annealing can also be 1.5 or higher." Paragraph [0029] records: "O: 0.007 wt%. O is an element that reduces the workability of steel and is preferably low, but its content can be allowed up to 0.007 wt%." Paragraph [0032] records: "Ti, Nb, V, Zr are all elements useful for suppressing the generation of Cr carbonitides during welding and suppressing sensitization, and are added in amounts of 0.01 wt% or more. However, if these addition amounts exceed 0.5 wt%, large inclusions are generated, significantly deteriorating toughness. Therefore, any of these elements are in the range of 0.01-0.5 wt%."

Evidence 3 description paragraph [0005] records: "The inventors of this invention, in order to achieve the above purpose, considering that {111} texture is effective for improving deep drawability in austenitic stainless steel sheets as mentioned above, conducted various studies on methods to develop {111} texture. As a result, it was found that by appropriately controlling hot rolling conditions, especially by making the temperature of the final pass during hot rolling (hot rolling end temperature) significantly higher than the conventional temperature (around 900-1000°C), a texture that significantly increases the accumulation degree of {111} parallel to the sheet surface of the hot-rolled steel sheet can be formed." Paragraph [0020] records: "P: 0.02 wt% or less. As shown in Figure 3, by limiting P to 0.02 wt% or less, the accumulation degree of {111} parallel to the sheet surface increases, and the limiting drawing ratio increases. Therefore, it is set to 0.02 wt% or less, preferably 0.015 wt% or less." Paragraph [0026] records: "O: 0.01 wt%. O is an element that reduces the workability of steel and is desired to be reduced, but its content can be allowed up to 0.01 wt%. Furthermore, preferably, 0.007 wt% can be set as the upper limit." Paragraph [0029] records: "Ti, Nb, V, Zr are all elements useful for suppressing the generation of Cr carbonitides during welding and suppressing sensitization, and are added in amounts of 0.01 wt% or more. However, if these addition amounts exceed 0.5 wt%, large inclusions are generated, significantly deteriorating toughness. Therefore, any of these elements are in the range of 0.01-0.5 wt%."

The reasoning of the challenged decision in this case regarding the evaluation of inventiveness is as follows:

"According to the records of the description of this patent (see pages 4-6 of the description), the purpose of this patent is to provide an inexpensive austenitic stainless steel pipe with excellent water vapor oxidation resistance. The entire steel pipe has a homogeneous, complete-grained fine-grained structure, and this fine-grained structure does not change due to welding or high-temperature bending processing during construction. In the prior art, because Nb or Ti carbonitides lack stability at high temperatures, it is difficult to form a stable, homogeneous, complete-grained fine-grained structure. Furthermore, Nb or Ti carbonitides are prone to re-dissolution or aggregation coarsening during welding or high-temperature bending processing, making it difficult to maintain the fine-grained structure. This patent found that in Nb-containing steel with uniformly dispersed Ti2O3, during heat treatment of the product, composite precipitates with Ti2O3 as the core and Nb carbonitides precipitated around it are uniformly dispersed and generated. These composite precipitates can have a fine-graining effect, and because these composite precipitates are stable at high temperatures, they do not dissolve during welding or high-temperature bending processing, thus maintaining the fine-grained structure. By heat treating steel that has uniformly dispersed Ti2O3 generated by adding Ti and has an Nb content in a suitable range (0.3-1.5 mass%), the above composite precipitates can be uniformly dispersed and generated. It can be seen that the stainless steel of this patent, through the specific content ratio of Nb, Ti, and O elements, obtains the above composite precipitates and achieves corresponding technical effects.

In comparison, as the closest prior art, Evidence 1-3 do not mention improving stainless steel performance by generating composite precipitates through the specific content ratio of the above three elements.

The requester believes that Evidence 1-3 disclose relevant content ratios and provide corresponding technical motivation.

In this regard, the collegial panel holds: In Evidence 1-3, the addition effects of Nb and Ti are different from those in this patent. For example, Evidence 1 further discloses (see paragraph 11 of its description) that Ti, Nb, V, Zr, Ta, B, Ca, Si, Mo, W, Al, Cu, Co, Mn, and other elements are appropriately added to Fe-Cr-Ni alloys to improve austenite phase stabilization, hot workability, weldability, workability, and corrosion resistance, etc.; in Evidence 2 and 3, Ti, Nb, V, Zr are all elements useful for suppressing the generation of Cr carbonitides during welding and suppressing sensitization (see paragraph 32 of Evidence 2 description and paragraph 29 of Evidence 3 description). It can be seen that in the above three pieces of evidence, Nb and Ti essentially play the same role in steel as in the prior art. Moreover, from their addition content, it can be seen that Nb and Ti, together with other multiple elements, serve as parallel optional elements that can replace each other. None of the three pieces of evidence contain examples simultaneously adding Nb and Ti. Even if Evidence 1 contains examples disclosing Ti and O content, these examples still do not disclose Nb content. It can be seen that Evidence 1-3 essentially do not disclose a scheme simultaneously adding Nb and Ti. Furthermore, although all three pieces of evidence mention the Nb element, as mentioned earlier, Nb therein serves as an element parallel and optional with Ti and other elements, and the role of Nb therein is different from that in this patent. None of the three pieces of evidence provide technical teaching on improving stainless steel performance by generating composite precipitates through the specific content ratio of Nb, Ti, and O as in this patent. Therefore, persons skilled in the art, based on the existing evidence, have no motivation to simultaneously add Nb and Ti to steel according to a specific ratio to obtain the specific effects of this patent. On the contrary, when a certain amount of Ti has already been added in the examples of Evidence 1, persons skilled in the art, without clear teaching, would generally find it difficult to further add Nb in such high content as in this patent. In summary, Evidence 1-3 do not simultaneously disclose the content ratio of Nb, Ti, and O elements in this patent, nor do they mention improving stainless steel performance by generating composite precipitates through the specific content ratio of the above three elements.

Furthermore, the requester did not use other evidence to evaluate the content of Nb and Ti, so this decision will not provide specific comments on the content of other evidence. In summary, the requester's invalidation ground that claims 1-10 lack inventiveness cannot be established."

The above facts are evidenced by the description of this patent, Evidence 1, Evidence 2, Evidence 3, the challenged decision, and other materials on file.

This court holds: The priority date of this patent is after the implementation date of the Patent Law (2000 Amendment) (July 1, 2001) and before the implementation date of the Patent Law (2008 Amendment) (October 1, 2009). This case should apply the Patent Law (2000 Amendment). The focal issue of dispute in the second instance of this case is: whether the claims of this patent possess inventiveness.

Article 22, Paragraph 3 of the Patent Law stipulates: "Inventiveness means that, as compared with the technology existing before the date of filing, the invention has prominent substantive features and represents a notable progress, and the utility model has substantive features and represents progress." An invention has prominent substantive features means that, to a person skilled in the art, the invention is non-obvious compared with the prior art. An invention has notable progress means that the invention can produce beneficial technical effects compared with the prior art. Whether an invention possesses inventiveness requires judging whether, to a person skilled in the art, the claimed invention is obvious compared with the prior art. This is usually carried out according to the following three steps, the so-called "three-step method" for inventiveness determination: First, determine the closest prior art; second, determine the distinguishing features between the invention and the closest prior art, and determine the actual technical problem solved by the invention based on the technical effects that can be achieved by these distinguishing features; third, starting from the closest prior art and the actual technical problem solved by the invention, determine whether the prior art provides motivation to apply the distinguishing features to the closest prior art to solve its existing technical problem, thereby judging whether the claimed invention is obvious to a person skilled in the art.

(I) Regarding the Claims Serving as the Examination Basis for This Case

After the challenged decision in this case was issued, A Japanese Corporation, as the patentee, amended the claims of this patent in another invalidation procedure, which was accepted by the National Intellectual Property Administration. That is, the amended claims 1-8 in the other case are substantially consistent in content with the amended claims 3-10 in this case. During the first-instance trial of this case, A Certain Stainless Steel Pipe Company also had no objection to this. Therefore, the first-instance court's handling that this case can still adjudicate whether the challenged decision's determination regarding the inventiveness of the pre-amendment claims 3-10 is lawful is not inappropriate. However, for convenience of expression, this court still uses the amended claims 1-10 in this case as the examination basis.

(II) Regarding Whether the Challenged Decision's Method of Evaluating Inventiveness is Appropriate

The challenged decision, after analyzing the claims and description of this patent, determined that the stainless steel of this patent obtains composite precipitates through the specific content ratio of Nb, Ti, and O elements and produces corresponding technical effects. In comparison, as the closest prior art, Evidence 1-3 do not mention improving stainless steel performance by generating composite precipitates through the specific content ratio of the above three elements. The first-instance judgment pointed out that the challenged decision's consideration of the specific content ratio of Nb, Ti, and O elements in the claims together to evaluate inventiveness lacks factual and legal basis.

In this regard, this court holds that the challenged decision generally pointed out that Evidence 1-3 do not mention improving stainless steel performance by generating composite precipitates through the specific content ratio of Nb, Ti, and O elements, thereby determining that this patent possesses inventiveness. The challenged decision listed three different patent documents as the closest prior art together. Although this can be understood as still using these three comparison documents respectively as the closest prior art for comparison, the challenged decision did not fully analyze and discuss the inventiveness of this patent in accordance with the usual "three-step method" for inventiveness determination. It did not specifically analyze and determine the distinguishing features possessed by each claim of this patent compared to these three comparison documents, and further did not, based on this, determine the actual technical problem solved by this patent relative to the closest prior art and analyze whether there is technical motivation in the prior art. Although the so-called "three-step method" is not the only method for inventiveness determination, in the absence of special circumstances where other methods can more concisely and reliably evaluate inventiveness, the so-called "three-step method" should generally still be followed. This case does not have such circumstances where the so-called "three-step method" is unsuitable. The challenged decision's method of evaluating whether this patent possesses inventiveness is somewhat inappropriate and incomplete. However, as analyzed and commented by this court later, this does not mean that the conclusion of the challenged decision is erroneous, necessitating its revocation and the issuance of a new examination decision.

(III) Regarding Whether Claim 1 of This Patent Possesses Inventiveness

1. Understanding of Claim 1 of This Patent

Article 26, Paragraph 3 of the Patent Law stipulates: "The description shall set forth the invention or utility model in a manner sufficiently clear and complete so as to enable a person skilled in the relevant field of technology to carry it out; where necessary, drawings shall be appended. The abstract shall state briefly the main technical points of the invention or utility model." Article 56, Paragraph 1 of the same law stipulates: "The extent of protection of the patent right for an invention or utility model shall be determined by the terms of the claims. The description and the appended drawings may be used to interpret the claims." The patent description provides detailed information on the technical field, background technology, technical problem to be solved, technical solution adopted to solve the technical problem, technical effects that can be produced by the technical solution, etc., of the invention or utility model. Its role is to clearly and completely disclose the technical solution of the invention or utility model, enabling persons skilled in the relevant field to understand and implement the invention or utility model, thereby providing new and useful technical information to the public. Content not recorded in the claims but based on explanations of the purpose of the invention, application scenarios, and mechanism of action in the description belongs to explanations of the claims and does not belong to limitations on the scope of protection of the claims. In the process of evaluating inventiveness, citing the description's explanation of the purpose of the invention and application scenarios based on the need to determine whether the prior art provides technical motivation does not belong to narrowing the scope of protection of the claims but rather interpreting the claims in combination with the purpose of the invention recorded in the description. Claim 1 of this patent is a material product claim. This type of claim often only limits the chemical composition and/or physical structure of the material without describing its production process, mechanism of action, etc., in detail in the claims. If only the claims are read, persons skilled in the art cannot fully understand the purpose of limiting the relevant chemical composition and/or physical structure. At this time, further reading of the description is needed to obtain a correct understanding of the scope of protection of the claims.

Claim 1 of this patent limits the mass percentage of chemical components of an austenitic stainless steel pipe with excellent water vapor oxidation resistance and limits its physical structure to a fine-grained structure with an austenite grain size number of 7 or higher. This drafting method is common for patents in the material field. For claims limited only by chemical substance composition and performance parameters, persons skilled in the art need to read the description to further understand the background technology, technical concept, technical problem to be solved of this patent, and whether the product can actually be manufactured, i.e., the feasibility of the production process. In this regard, the description of this patent has detailed records, and the challenged decision also cited them. The purpose of this patent is to provide an austenitic stainless steel pipe with the characteristic of excellent water vapor oxidation resistance. The description of this patent further elaborates that steel pipes with a homogeneous, complete-grained fine-grained structure have excellent water vapor oxidation resistance. This patent found that Nb or Ti carbonitides are prone to re-dissolution or aggregation coarsening during welding or high-temperature bending processing, making it difficult to maintain the fine-grained structure. At the same time, in Nb-containing steel with uniformly dispersed Ti2O3, during heat treatment of the product, composite precipitates with Ti2O3 as the core and Nb carbonitides precipitated around it are uniformly dispersed and generated. These composite precipitates can have a fine-graining effect, and because these composite precipitates are stable at high temperatures, they do not dissolve during welding or high-temperature bending processing, thus maintaining the fine-grained structure. By heat treating steel that has uniformly dispersed Ti2O3 generated by adding Ti and has an Nb content in a suitable range (0.3-1.5 mass%), the above composite precipitates can be uniformly dispersed and generated. It can be seen that by reading the description of this patent, persons skilled in the art can clearly know that this patent, to prevent the generation of water vapor oxidation scale on the inner surface of the stainless steel pipe, needs to obtain an austenitic stainless steel pipe product with a "fine-grained structure with an austenite grain size number of 7 or higher." To maintain the fine-grained structure, it is necessary to solve the problem that Nb or Ti carbonitides are prone to re-dissolution. This is precisely the technical problem to be solved by this patent. Among the content limits of each element in the austenitic stainless steel pipe limited by this patent, not all element content limits are related to the above technical problem to be solved by this patent. Only the content of the three elements Nb, Ti, and O is closely related. Persons skilled in the art will focus on the fact that the specific ratio of the content of the three elements Nb, Ti, and O is the technical means to solve the technical problem of this patent, and this specific ratio has been recorded in the claims.

The first-instance judgment also pointed out: "Even if, as recorded in the description of this patent, this patent improves stainless steel performance by generating composite precipitates, the description of this patent also records that cooling speed is also a factor in whether composite precipitates can be generated. Based on this, it can be seen that the challenged decision's determination conclusion that 'composite precipitates are obtained through the specific content ratio of Nb, Ti, and O elements, achieving corresponding technical effects' is erroneous." In this regard, this court holds that, according to the relevant records in the description of this patent regarding "cooling the steel pipe heated in the first method or the steel pipe formed in the second method. At this time, if the cooling rate from 800°C to 500°C is lower than 0.25°C/second, coarse Nb carbonitides or Cr carbonitides will precipitate during cooling, preventing the generation of finely dispersed Nb composite carbonitides, which is the purpose of this invention, and thus the desired fine-grained structure cannot be obtained," persons skilled in the art, by reading the description, can know that adopting the specific manufacturing method of this patent is to obtain a "fine-grained structure with an austenite grain size number of 7 or higher." That is, obtaining a "fine-grained structure with an austenite grain size number of 7 or higher" already indicates the need to adopt heat treatment methods including cooling speed. Under the condition that the claims simultaneously satisfy the specific content ratio of Nb, Ti, and O elements and "fine-grained structure with an austenite grain size number of 7 or higher," the finely dispersed Nb composite carbonitides described in the description of this patent can be generated. When understanding the claims of this patent, the limiting effect of "fine-grained structure with an austenite grain size number of 7 or higher" should not be ignored. The first-instance judgment's determination in this regard is somewhat inappropriate, but the challenged decision's commentary on this patent also did not clearly point out the limiting effect of "fine-grained structure with an austenite grain size number of 7 or higher," which is also somewhat inappropriate.

2. Whether Claim 1 of This Patent Possesses Inventiveness Relative to Evidence 1, 2, and 3 Respectively as the Closest Prior Art

Evidence 1 discloses an Fe-Cr-Ni series alloy with excellent corrosion resistance and workability, wherein alloy No. 15 has a grain size number of 11, and the upper limits of Ti content and O content in the alloy composition fall within the range of claim 1 of this patent. The distinguishing features between claim 1 of this patent and Evidence 1 are: (1) Evidence 1 does not disclose using this alloy as a steel pipe; (2) Evidence 1 does not disclose Nb and its content; (3) Evidence 1 does not disclose the lower limit of O content. According to the records in the description of Evidence 1, to improve the corrosion resistance and workability of the alloy, the technical concept it provides is to control the total amount of O+P+S, indicating that O is controlled as an impurity. In contrast, the technical concept of this patent is to control the content ratio of Nb, Ti, and O elements, so that in Nb-containing steel with uniformly dispersed Ti2O3, during heat treatment of the product, composite precipitates with Ti2O3 as the core and Nb carbonitides precipitated around it are uniformly dispersed and generated. Furthermore, by heat treating steel that has uniformly dispersed Ti2O3 generated by adding Ti and has an Nb content in a suitable range (0.3-1.5 mass%), the above composite precipitates can be uniformly dispersed and generated. The above composite precipitates have the same fine-graining effect as Nb or Ti carbonitides. Not only can a homogeneous, complete-grained fine-grained structure be stably obtained, but also because the composite precipitates are stable at high temperatures, they do not re-dissolve during welding or high-temperature bending processing in construction, thus maintaining the fine-grained structure. Moreover, the upper and lower limits of O content are limited. As described in the description of this patent, "O, like Ti above, is an indispensable element for uniformly dispersing and generating Ti2O3, which becomes the core of the above composite precipitates. When its content is less than 0.001%, Ti2O3 cannot be generated. On the other hand, when its content exceeds 0.008%, coarse oxides other than Ti2O3 are formed, significantly impairing steel quality, strength, and toughness. Therefore, the O content is set at 0.001-0.008%," meaning a certain content of O is beneficial in this patent. It can be seen that the technical concept of this patent is different from that of Evidence 1, and the roles of adding Ti and O are also different. Therefore, the actual technical problem solved by this patent relative to Evidence 1 should be how to generate composite precipitates with Ti2O3 as the core and Nb carbonitides precipitated around it. Because Evidence 1 has a different technical concept from this patent, alloy No. 15 does not mention Nb and its content, and the role of O is also different. Persons skilled in the art, based on Evidence 1, have no motivation to add Nb with a specific content. The prior art also does not provide technical teaching to simultaneously add Nb, O, and Ti to steel pipes, and there is no common general knowledge proving that controlling the content ratio of Nb, Ti, and O elements can form composite precipitates with Ti2O3 as the core and Nb carbonitides precipitated around it and achieve corresponding technical effects. Therefore, A Certain Stainless Steel Pipe Company's invalidation ground that claim 1 of this patent lacks inventiveness relative to Evidence 1 or the combination of Evidence 1 and common general knowledge cannot be established.

Evidence 2 discloses an austenitic stainless steel cold-rolled steel sheet with small springback. The distinguishing features between claim 1 of this patent and Evidence 2 are: (1) This patent is a steel pipe, while Evidence 2 is a steel sheet; (2) Evidence 2 does not limit the lower limit of O; (3) Evidence 2 does not limit the austenite grain size number to 7 or higher. According to the records in the description of Evidence 2, the purpose of this invention is how to achieve small springback after press forming of austenitic stainless steel cold-rolled steel sheets even when P is a relatively high content of 0.04 wt% or less. Although Evidence 2 mentions Nb, Ti, and O, and the numerical values of Nb and Ti content overlap with those of this patent, it only mentions that O is an element that reduces the workability of steel, and the lower the content, the better. Ti and Nb are elements useful for suppressing the generation of Cr carbonitides during welding and suppressing sensitization. It can be seen that the technical concept of Evidence 2 is different from that of this patent. Evidence 2 does not mention an austenite grain size number of 7 or higher, and the role of O is also different. Persons skilled in the art, based on Evidence 2, would find it difficult to think that the obtained product is stainless steel with an austenite grain size number of 7 or higher. There is also no evidence of common general knowledge proving that controlling the content ratio of Nb, Ti, and O elements can form composite precipitates with Ti2O3 as the core and Nb carbonitides precipitated around it and achieve corresponding technical effects. The other evidence submitted by A Certain Stainless Steel Pipe Company in the invalidation procedure also does not provide corresponding technical motivation. Therefore, A Certain Stainless Steel Pipe Company's invalidation ground that claim 1 of this patent lacks inventiveness relative to Evidence 2 or the combination of Evidence 2 and common general knowledge or other evidence cannot be established.

Evidence 3 discloses an austenitic stainless steel hot-rolled steel sheet with excellent deep drawability. Its technical concept is similar to that of Evidence 2 and also does not limit the lower limit of O or the austenite grain size number to 7 or higher. Based on the same reasons above, A Certain Stainless Steel Pipe Company's invalidation ground that claim 1 of this patent lacks inventiveness relative to Evidence 3 or the combination of Evidence 3 and common general knowledge or other evidence also cannot be established.

Since claim 1 of this patent possesses inventiveness relative to the invalidation evidence submitted by A Certain Stainless Steel Pipe Company in this case, its dependent claims and corresponding method claims also possess inventiveness.

In summary, the appeal requests of the National Intellectual Property Administration and A Japanese Corporation are both established and should be supported. Although the reasoning of the challenged decision is somewhat flawed, its conclusion is correct, and the first-instance judgment should be revoked. In accordance with Article 69 and Items 1 and 2 of Article 89, Paragraph 1, and Paragraph 3 of the Administrative Procedure Law of the People's Republic of China, the judgment is as follows:

1. Revoke the administrative judgment (2022) Jing 73 Xing Chu No. 13589 of the Beijing Intellectual Property Court;
2. Dismiss the lawsuit of A Certain Stainless Steel Pipe Company.

The first and second-instance case acceptance fees, each RMB 100, shall be borne by A Certain Stainless Steel Pipe Company. The National Intellectual Property Administration and A Japanese Corporation have prepaid the second-instance case acceptance fees of RMB 100 each, which should be refunded. A Certain Stainless Steel Pipe Company shall pay the second-instance case acceptance fee of RMB 100.

This judgment is final.

Presiding Judge: Tai Zhonglin
Judge: Cen Hongyu
Judge: Liu Xiaomei
Judge: Kong Liming
Judge: Jiao Xinhui

September 29, 2025

Judge Assistant: Zhang Zhen
Technical Investigator: Jiang Xianquan
Clerk: Zhang Zhaolin
Clerk: Nie Qi