A high-strength corrosion-resistant austenitic stainless steel for supercritical carbon dioxide environment and a method for manufacturing the same

Abstract

The application discloses a high-strength corrosion-resistant austenitic stainless steel for a supercritical carbon dioxide environment, which comprises nickel, chromium, molybdenum, copper, manganese, niobium, carbon, aluminum, silicon, and iron; wherein the mass fraction of nickel is 22% to 30%, the mass fraction of chromium is 16% to 25%, the mass fraction of molybdenum is 0% to 5%, the mass fraction of copper is 0.5% to 2%, the mass fraction of manganese is 0.5% to 2.5%, the mass fraction of niobium is 0.5% to 1.2%, the mass fraction of carbon is 0.01% to 0.15%, the mass fraction of aluminum is 0% to 4%, the mass fraction of silicon is 0.5% to 1.5%, the mass fraction of nitrogen is 0 to 0.1%, and the balance is iron. The high-strength austenitic stainless steel prepared by the application has good corrosion resistance and high-temperature strength in a high-temperature supercritical carbon dioxide environment.

Description

Technical Field

[0001] This invention belongs to the field of alloys, specifically relating to a trace element-strengthened, corrosion-resistant austenitic stainless steel for use in supercritical carbon dioxide environments and its preparation method. Background Technology

[0002] Supercritical gas-cooled reactors (SGCRs) are one of the fourth-generation reactor concepts, with supercritical carbon dioxide (S-CO2) as one of their primary working fluids. When both temperature and pressure exceed the critical point (31.2℃ / 7.38MPa), carbon dioxide transforms into supercritical carbon dioxide (S-CO2), possessing both the solubility of a liquid and the diffusivity of a gas, exhibiting advantages such as good compressibility and high heat transfer efficiency. Supercritical carbon dioxide (S-CO2) has good compressibility and heat transfer properties, and is considered a potential heat transfer fluid with applications in nuclear power, solar energy, and thermal power generation. Nuclear reactors using S-CO2 as the working fluid offer advantages such as small footprint and high operating efficiency, making them a currently popular research direction. S-CO2 gas-cooled reactors operate at temperatures of 500℃–650℃, significantly higher than traditional commercial water-cooled reactors. Below 400℃, CO2 is stable, and existing austenitic stainless steel can form a chromium oxide film for protection, resulting in extremely low corrosion rates. However, at high temperatures, carbonization and oxidation reactions intensify rapidly, leading to severe oxide film peeling and matrix carburization on the metal surface, resulting in structural material failure. Furthermore, fuel cladding with thin-walled structures operates at higher temperatures and is more susceptible to corrosion compared to other materials. Therefore, existing austenitic stainless steels are no longer suitable for the high-temperature, high-pressure environments under supercritical carbon dioxide.

[0003] In austenite, elements such as aluminum and silicon can form protective oxide films—alumina or silicon oxide. Because aluminum / silicon oxide films offer greater high-temperature stability and a slower growth rate compared to chromium oxide films, they provide superior protection for the alloy matrix. Simultaneously, the addition of trace elements such as Mo and N provides solid solution strengthening while precipitating dispersed strengthening phases, including γ' phase, B2-NiAl phase, and Laves phase, further enhancing the alloy's high-temperature mechanical properties. These excellent high-temperature properties meet the requirements for austenitic steel applications in supercritical carbon dioxide systems.

[0004] Existing austenitic stainless steels rely on the formation of chromium oxide (Cr2O3) to provide corrosion resistance. However, under extreme high-temperature environments, chromium oxide exhibits poor stability and a rapid growth rate, failing to meet the required corrosion resistance. Furthermore, high temperatures accelerate creep and microcrack propagation, thereby reducing material strength. Therefore, existing austenitic stainless steels are no longer suitable for high-temperature, high-pressure environments such as supercritical carbon dioxide. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a high-strength, corrosion-resistant austenitic stainless steel for use in supercritical carbon dioxide environments.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: the austenitic stainless steel contains nickel, chromium, molybdenum, copper, manganese, niobium, carbon, aluminum, silicon, and iron;

[0009] Of which, based on the mass percentage of raw materials, the nickel content is 22%–30%, the chromium content is 16%–25%, the molybdenum content is 2%–5%, the copper content is 0.5%–2%, the manganese content is 0.5%–2.5%, the niobium content is 0.5%–1.2%, the carbon content is 0.01%–0.15%, the aluminum content is 1.5%–3.5%, the silicon content is 0.5%–2%, and the balance is made up to 100% by iron.

[0010] In a preferred embodiment of the preparation method described in this invention, the nickel mass fraction is 26%, the chromium mass fraction is 19%, the molybdenum mass fraction is 4%, the copper mass fraction is 1.5%, the manganese mass fraction is 2%, the niobium mass fraction is 0.6%, the carbon mass fraction is 0.04%, the silicon mass fraction is 1.5%, the aluminum mass fraction is 2.5%, and the balance is iron.

[0011] In a preferred embodiment of the preparation method described in this invention, the austenitic stainless steel has the following characteristics:

[0012] (a) Oxidation weight gain in supercritical carbon dioxide at 600℃ for 1000 h is less than 8.5 mg / dm³. 2 The lowest level can be below 8.2 mg / dm³. 2 ;

[0013] (b) Yield strength exceeding 550 MPa in supercritical carbon dioxide at 600 °C;

[0014] (c) Tensile strength exceeding 610 MPa in supercritical carbon dioxide at 600℃;

[0015] (d) The elongation exceeds 30% in supercritical carbon dioxide at 600℃.

[0016] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing high-strength corrosion-resistant austenitic stainless steel for use in supercritical carbon dioxide environments.

[0017] As a preferred embodiment of the preparation method described in this invention, the pure metal raw materials Fe, Cr, Ni, Mo, Nb and C are mixed in proportion and then vacuum-electro-melted. After the steel is liquefied and cleaned, the remaining C and Al are added and fully melted before refining.

[0018] After refining, argon or a nitrogen-argon mixture is introduced, Si and Mn are added, and after holding at the temperature, Cu is added to fully melt it. The temperature is then adjusted and the mixture is cast into steel ingots.

[0019] The steel ingot is first heated and held at a certain temperature, then heated and held at a certain temperature, and finally cooled and held at a certain temperature before forging begins. After forging is completed, it is air-cooled to obtain a stainless steel forging billet, which is then polished to remove the oxide scale.

[0020] Austenitic stainless steel is obtained by heat treatment of stainless steel forging billets after removing oxide scale.

[0021] In a preferred embodiment of the preparation method described in this invention, the vacuum electric melting process includes,

[0022] Melting temperature 1500℃, holding time ≥10 minutes, vacuum degree <10 -2 pa.

[0023] As a preferred embodiment of the preparation method described in this invention, the refining process involves holding the molten steel at 1500°C for ≥10 minutes.

[0024] As a preferred embodiment of the preparation method described in this invention, the steel ingot is first heated and held at a certain temperature, then heated and held at a certain temperature, and finally cooled and held at a certain temperature before forging begins. Specifically, it is first heated to 800°C at a heating rate of 100°C / h for 1-2 hours to achieve uniform temperature, then heated to 1200°C at a heating rate of 100°C / h for 3 hours, and then cooled to 1180°C for 1 hour.

[0025] As a preferred embodiment of the preparation method described in this invention, the initial forging temperature is not lower than 1180℃ and not higher than 1250℃, and the final forging temperature is 950~1000℃.

[0026] As a preferred embodiment of the preparation method described in this invention, the heat treatment is a solution treatment at 1180-1250°C for 60 min, followed by water cooling, and then an aging treatment at 700°C for 100 h.

[0027] Another objective of this invention is to overcome the shortcomings of the prior art and provide an application of high-strength corrosion-resistant austenitic stainless steel in supercritical carbon dioxide systems.

[0028] Beneficial effects of this invention:

[0029] (1) The novel high-strength austenitic stainless steel prepared by this invention is designed for high-temperature supercritical carbon dioxide environment and has good corrosion resistance and high-temperature strength in this environment.

[0030] (2) The novel high-strength austenitic stainless steel resistant to supercritical carbon dioxide corrosion prepared by this invention is based on austenitic steel with nickel, chromium, molybdenum, copper, manganese, niobium, carbon, and the balance iron. The alloying elements are selectively added, including Al and Si. Specifically, the mass fractions are: nickel 22%–30%, chromium 16%–25%, molybdenum 0%–5%, copper 0.5%–2%, manganese 0.5%–2.5%, niobium 0.5%–1.2%, carbon 0.01%–0.15%, aluminum 0%–4%, silicon 0.5%–1.5%, and nitrogen 0%–0.1%. By controlling the Al, Si, and N contents and combining forging and heat treatment processes, the austenitic steel of this invention exhibits excellent high-temperature strength and high-temperature corrosion resistance. Its weight gain after 1000 hours of oxidation in supercritical carbon dioxide at 600℃ is less than 8.5 mg / dm³. 2 The optimal component ratio results in a concentration lower than 8.2 mg / dm³. 2 It can meet the material performance requirements in a supercritical carbon dioxide environment at 600℃.

[0031] (3) The preparation process of the novel high-strength austenitic stainless steel resistant to supercritical carbon dioxide corrosion prepared by the present invention includes vacuum induction melting, refining, alloying, casting and forging. Under the supercritical carbon dioxide environment at high temperature (≥550℃), the high-strength corrosion-resistant austenitic stainless steel can not only provide excellent corrosion resistance to the alloy matrix by forming a dense and stable alumina protective film, but also introduce solid solution strengthening and various strengthening precipitates (including but not limited to MC phase, Laves phase, B2-NiAl phase, γ' phase) into the austenitic stainless steel to provide high-temperature strength to the alloy through the addition of trace elements. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0033] Figure 1 The corrosion weight gain curves of austenitic steel provided in Examples 1 to 7 and Comparative Example 1 of this invention are shown in the 500-h supercritical carbon dioxide corrosion curves at 600°C.

[0034] Figure 2 The mechanical properties of austenitic steels provided in Examples 1-2 and Comparative Example 1 of this invention in supercritical carbon dioxide at 600℃ are shown.

[0035] Figure 3 These are SEM images of Embodiments 1-3 and Comparative Example 1 of the present invention.

[0036] Figure 4 These are SEM images of embodiments 4 to 7 of the present invention.

[0037] Figure 5 This is a schematic diagram of the supercritical carbon dioxide corrosion testing machine of the present invention.

[0038] Figure 6 This invention relates to a supercritical carbon dioxide corrosion testing machine. Detailed Implementation

[0039] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0040] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0041] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0042] The high-strength, corrosion-resistant austenitic stainless steel prepared by this invention contains 22%–30% nickel, 16%–25% chromium, 0%–5% molybdenum, 0.5%–2% copper, 0.5%–2.5% manganese, 0.5%–1.2% niobium, 0.01%–0.15% carbon, 0%–4% aluminum, and 0.5%–1.5% silicon, with the balance being iron, to achieve optimal corrosion resistance and high-temperature strength.

[0043] The nitrogen-argon mixture and argon gas used were purchased from Licon Air Liquide.

[0044] Example 1

[0045] This invention provides a novel method for preparing high-strength, corrosion-resistant austenitic stainless steel strengthened by trace elements:

[0046] By mass fraction, it comprises the following components: 26% Ni, 19% Cr, 2% Mn, 1.5% Cu, 4% Mo, 1.5% Si, 0.6% Nb, 0.04% C, 2.5% Al, with the remainder being Fe.

[0047] (1) Using a vacuum induction furnace, pure metal raw materials Ni, Cr, Mo, Nb, C, and the balance Fe are mixed and placed in a crucible for vacuum melting. The melting temperature is 1500℃, the holding time is not less than 10 minutes, and the vacuum degree is less than 10. -2 pa. After the steel is liquefied and cleaned, Al is added and fully melted before refining. The refining conditions are to keep the molten steel at 1500℃ for 15 minutes.

[0048] (2) After refining, 0.04 MPa argon gas is introduced into the induction furnace, and Si and Mn are added to further reduce the oxygen and sulfur content.

[0049] (3) After holding the temperature for 10 minutes, Cu is added and fully melted. The temperature is adjusted and the ingot is cast into a steel ingot. The smelted steel ingot is formed by forging. During the forging process, the steel ingot is placed in a heating furnace and heated to 800°C at a heating rate of 100°C / h for 1-2 hours. Then, it is heated to 1200°C at a heating rate of 100°C / h and held for 3 hours. Then, it is cooled to 1180°C and held for 1 hour before forging begins. The initial forging temperature is not lower than 1180°C and not higher than 1250°C. The final forging temperature is 950-1000°C. The stainless steel forging billet is obtained by air cooling and then polished to remove the oxide scale.

[0050] The heat treatment process is as follows: the stainless steel forging billet with oxide scale removed is solution treated at 1180-1250℃ for 60 minutes, water cooled, and then aged at 700℃ for 100 hours to obtain a new type of trace element strengthened high-strength corrosion-resistant austenitic stainless steel.

[0051] Comparative Example 1

[0052] The difference from Example 1 is that, by mass fraction, it includes the following components: 26% Ni, 19% Cr, 2% Mn, 1.5% Cu, 0.5% Si, 0.6% Nb, 0.04% C, with the remainder being Fe.

[0053] Comparative Example 2

[0054] The difference from Example 1 is that, by mass fraction, it includes the following components: 26% Ni, 19% Cr, 2% Mn, 1.5% Cu, 2% Mo, 0.5% Si, 0.6% Nb, 0.04% C, with the remainder being Fe.

[0055] Comparative Example 3

[0056] The difference from Example 1 is that, by mass fraction, it includes the following components: 26% Ni, 19% Cr, 2% Mn, 1.5% Cu, 0.5% Si, 0.6% Nb, 0.06% N, 0.04% C, with the remainder being Fe.

[0057] (1) Using a vacuum induction furnace, pure metal raw materials Ni, Cr, Nb, C, and the balance Fe are mixed and placed in a crucible for vacuum melting. The melting temperature is 1500℃, the holding time is not less than 10 minutes, and the vacuum degree is less than 10. -2 The refining conditions are to hold the molten steel at 1500℃ for 15 minutes;

[0058] (2) After refining, a nitrogen-argon mixture of 0.04 MPa is introduced into the induction furnace, and Si and Mn are added to further reduce the oxygen and sulfur content.

[0059] (3) After holding the temperature for 10 minutes, Cu is added and fully melted. The temperature is adjusted and the ingot is cast into a steel ingot. The smelted steel ingot is formed by forging. During the forging process, the steel ingot is placed in a heating furnace and heated to 800°C at a heating rate of 100°C / h for 1-2 hours. Then, it is heated to 1200°C at a heating rate of 100°C / h and held for 3 hours. Then, it is cooled to 1180°C and held for 1 hour before forging begins. The initial forging temperature is not lower than 1180°C and not higher than 1250°C. The final forging temperature is 950-1000°C. The stainless steel forging billet is obtained by air cooling and then polished to remove the oxide scale.

[0060] The heat treatment process is as follows: the stainless steel forging billet with oxide scale removed is solution treated at 1180-1250℃ for 60 minutes, water cooled, and then aged at 700℃ for 100 hours to obtain a new type of trace element strengthened high-strength corrosion-resistant austenitic stainless steel.

[0061] Comparative Example 4

[0062] The difference from Example 1 is that, by mass fraction, it includes the following components: 26% Ni, 19% Cr, 2% Mn, 1.5% Cu, 0.5% Si, 0.6% Nb, 0.04% C, 2.5% Al, with the remainder being Fe.

[0063] Comparative Example 5

[0064] The difference from Example 1 is that, by mass fraction, it includes the following components: 26% Ni, 19% Cr, 2% Mn, 1.5% Cu, 4% Mo, 1.5% Si, 0.6% Nb, 0.04% C, with the remainder being Fe.

[0065] Comparative Example 6

[0066] The difference from Example 1 is that, by mass fraction, it includes the following components: 26% Ni, 19% Cr, 2% Mn, 1.5% Cu, 4% Mo, 0.5% Si, 0.6% Nb, 0.04% C, 2.5% Al, with the remainder being Fe.

[0067] Comparative Example 7

[0068] The difference from Example 1 is that, by mass fraction, it includes the following components: 26% Ni, 19% Cr, 2% Mn, 1.5% Cu, 4% Mo, 1.0% Si, 0.6% Nb, 0.04% C, 2.5% Al, with the remainder being Fe.

[0069] Comparative Example 8

[0070] The difference from Example 1 is that, by mass fraction, it includes the following components: 26% Ni, 19% Cr, 2% Mn, 1.5% Cu, 4% Mo, 1.5% Si, 0.6% Nb, 0.06% N, 0.04% C, 2.5% Al, with the remainder being Fe.

[0071] (1) Pure metal raw materials Ni, Cr, Mo, Nb, C, and the balance Fe are mixed in a vacuum induction furnace and placed in a crucible for vacuum melting. The melting temperature is 1500℃, the holding time is not less than 10 minutes, and the vacuum degree is less than 10-2 Pa. After the steel is liquefied and cleaned, Al is added and fully melted before refining. The refining conditions are to keep the molten steel at 1500℃ for 15 minutes.

[0072] (2) After refining, a nitrogen-argon mixture of 0.04 MPa is introduced into the induction furnace, and Si and Mn are added to further reduce the oxygen and sulfur content.

[0073] (3) After holding the temperature for 10 minutes, Cu is added and fully melted. The temperature is adjusted and the ingot is cast into a steel ingot. The smelted steel ingot is formed by forging. During the forging process, the steel ingot is placed in a heating furnace and heated to 800°C at a heating rate of 100°C / h for 1-2 hours. Then, it is heated to 1200°C at a heating rate of 100°C / h and held for 3 hours. Then, it is cooled to 1180°C and held for 1 hour before forging begins. The initial forging temperature is not lower than 1180°C and not higher than 1250°C. The final forging temperature is 950-1000°C. The stainless steel forging billet is obtained by air cooling and then polished to remove the oxide scale.

[0074] The heat treatment process is as follows: the stainless steel forging billet with oxide scale removed is solution treated at 1180-1250℃ for 60 minutes, water cooled, and then aged at 700℃ for 100 hours to obtain a new type of trace element strengthened high-strength corrosion-resistant austenitic stainless steel.

[0075] Comparative Example 9

[0076] The difference from Example 1 is that, by mass fraction, it includes the following components: 26% Ni, 19% Cr, 2% Mn, 1.5% Cu, 4% Mo, 2.0% Si, 0.6% Nb, 0.04% C, 2.5% Al, with the remainder being Fe.

[0077] Comparative Example 10

[0078] The difference from Example 1 is that, by mass fraction, it includes the following components: 26% Ni, 19% Cr, 2% Mn, 1.5% Cu, 4% Mo, 1.5% Si, 0.6% Nb, 0.04% C, with the remainder being Fe.

[0079] Comparative Example 11

[0080] The difference from Example 1 is that, by mass fraction, it includes the following components: 26% Ni, 19% Cr, 2% Mn, 1.5% Cu, 4% Mo, 1.5% Si, 0.6% Nb, 0.04% C, 1.5% Al, with the remainder being Fe.

[0081] Comparative Example 12

[0082] The difference from Example 1 is that, by mass fraction, it includes the following components: 26% Ni, 19% Cr, 2% Mn, 1.5% Cu, 4% Mo, 1.5% Si, 0.6% Nb, 0.04% C, 3.0% Al, with the remainder being Fe.

[0083] Table 1. Mass percentage of each component in Example 1 and Comparative Examples 1-12

[0084] Ni Cr Mn Cu Mo Si Nb N C Al Fe Example 1 26 19 2 1.5 4 1.5 0.6 0 0.04 2.5 margin Comparative Example 1 26 19 2 1.5 0 0.5 0.6 0 0.04 0 margin Comparative Example 2 26 19 2 1.5 2 0.5 0.6 0 0.04 0 margin Comparative Example 3 26 19 2 1.5 0 0.5 0.6 0.06 0.04 0 margin Comparative Example 4 26 19 2 1.5 0 0.5 0.6 0 0.04 2.5 margin Comparative Example 5 26 19 2 1.5 4 1 0.6 0 0.04 0 margin Comparative Example 6 26 19 2 1.5 4 0.5 0.6 0 0.04 2.5 margin Comparative Example 7 26 19 2 1.5 4 1 0.6 0 0.04 2.5 margin Comparative Example 8 26 19 2 1.5 4 1.5 0.6 0.06 0.04 2.5 margin Comparative Example 9 26 19 2 1.5 4 2 0.6 0 0.04 2.5 margin Comparative Example 10 26 19 2 1.5 4 1.5 0.6 0 0.04 0 margin Comparative Example 11 26 19 2 1.5 4 1.5 0.6 0 0.04 1.5 margin Comparative Example 12 26 19 2 1.5 4 1.5 0.6 0 0.04 3.0 margin

[0085] Use a supercritical carbon dioxide corrosion testing machine, such as Figure 5 , 6The sample is suspended on a sample rack or special fixture inside the autoclave. The autoclave is then sealed, and the following parameters are tested at 600℃ and 10MPa. In the uniform corrosion test, corrosion sampling points are set at 100h, 300h, 500h, 700h, and 1000h. After each test, the sample is carefully removed, cleaned with alcohol, and dried in an oven for at least 4 hours before weighing. Except for a portion of the sample retained for further analysis, the remaining samples are returned to the autoclave for continued testing until final sampling is completed. In the stress corrosion test, after confirming that the system temperature and pressure conditions have reached the preset values, the tensile testing machine is started, with a tensile rate of 5×10⁻⁶. -7 s -1 The experiment continued until the sample broke, at which point it ended. The results are shown in Table 2.

[0086] Table 2

[0087]

[0088] By controlling trace elements, a multi-component embodiment was obtained, and the optimal strengthening method was found. Embodiment 1, which simultaneously achieved optimal corrosion resistance and high-temperature strength, was thus obtained. Figure 1 It can be seen that, in a high-temperature supercritical carbon dioxide environment, Example 1 exhibits the lowest corrosion weight gain over a 1000-hour experimental period. Figure 2 It can be seen that in a high-temperature supercritical carbon dioxide environment, Example 1 has excellent high-temperature strength and elongation. Figure 3 Figure 4 shows the tissue structure and morphology of the precipitated phase in the corresponding embodiment. Figure 5 This is a schematic diagram of the supercritical carbon dioxide corrosion testing machine of the present invention. Figure 6 This invention relates to a supercritical carbon dioxide corrosion testing machine. Example 1, through reasonable component control, exhibits a uniform microstructure and excellent corrosion resistance and high-temperature strength in a high-temperature supercritical carbon dioxide environment.

[0089] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for preparing high-strength, corrosion-resistant austenitic stainless steel for use in supercritical carbon dioxide environments, characterized in that: The high-strength corrosion-resistant austenitic stainless steel for supercritical carbon dioxide environments comprises, by mass fraction, the following components: 26% Ni, 19% Cr, 2% Mn, 1.5% Cu, 4% Mo, 1.5% Si, 0.6% Nb, 0.04% C, 2.5% Al, with the remainder being Fe. (1) Using a vacuum induction furnace, pure metal raw materials Ni, Cr, Mo, Nb, C, and the balance Fe are mixed and placed in a crucible for vacuum melting. The melting temperature is 1500℃, the holding time is not less than 10 minutes, and the vacuum degree is less than 10. -2 Pa; After the steel is liquefied and cleaned, Al is added and fully melted before refining. The refining conditions are to keep the molten steel at 1500℃ for 15 minutes. (2) After refining, 0.04 MPa argon gas is introduced into the induction furnace, and Si and Mn are added to further reduce the oxygen and sulfur content; (3) After holding the temperature for 10 minutes, Cu is added and fully melted. The temperature is adjusted and the ingot is cast into a steel ingot. The smelted steel ingot is forged. During the forging process, the steel ingot is placed in a heating furnace and heated to 800°C at a heating rate of 100°C / h for 1-2 hours. Then, it is heated to 1200°C at a heating rate of 100°C / h and held for 3 hours. Then, it is cooled to 1180°C and held for 1 hour before forging begins. The initial forging temperature is not lower than 1180°C and not higher than 1250°C. The final forging temperature is 950-1000°C. The stainless steel forging billet is obtained by air cooling and grinding to remove the oxide scale. The heat treatment process is as follows: the stainless steel forging billet with the oxide scale removed is solution treated at 1180-1250°C for 60 minutes, water cooled, and then aged at 700°C for 100 hours.

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