Austenitic stainless steel resistant to corrosion and stress corrosion cracking in supercritical carbon dioxide and preparation method of austenitic stainless steel

Abstract

The invention discloses austenitic stainless steel resistant to corrosion and stress corrosion cracking in supercritical carbon dioxide and a preparation method thereof.The austenitic stainless steel is prepared from, by mass, 24%-26% of nickel, 19.5%-20.5% of chromium, 0.6%-0.8% of manganese, 0.5%-0.7% of silicon, 0.5%-0.7% of niobium and the balance iron and inevitable impurities, and the mass fraction of nickel is 24%-26%, the mass fraction of chromium is 19.5%-20.5%, the mass fraction of manganese is 0.6%-0.8%, the mass fraction of silicon is 0.5%-0.7%, and the mass fraction of niobium is 0.5%-0.7%. The mass fraction of nitrogen is 0.04-0.12%, the mass fraction of carbon is 0.02-0.05%, and the balance is Fe; and the composite material has excellent corrosion resistance and stress corrosion cracking resistance in a supercritical carbon dioxide environment. The austenitic stainless steel prepared through the method has the advantages of being small in corrosion weight increment, good in creep property, long in stress corrosion crack initiation time, low in stress corrosion crack propagation rate and the like in the 650 DEG C / 15 MPa supercritical carbon dioxide service environment.

Description

Technical Field

[0001] The present invention belongs to the field of alloys, and in particular relates to an austenitic stainless steel resistant to corrosion and stress corrosion cracking in supercritical carbon dioxide and a preparation method thereof. Background Art

[0002] Carbon dioxide (CO2) has a moderate critical pressure and temperature (7.38 MPa, 31°C). Due to its high density, non-toxicity, abundant reserves, stable chemical properties, and dramatic thermodynamic property changes near its critical point, it is considered one of the most promising energy conversion fluids for nuclear reactors. The SC-CO2 Brayton cycle has attracted considerable attention due to its compact turbine machinery, simple cycle layout, high cycle efficiency at moderate turbine inlet temperatures, and low efficiency losses due to its dry cooling. Compared to the widely used steam Rankine cycle, the SC-CO2 Brayton cycle can achieve higher efficiency under high-temperature conditions. However, the construction of this type of reactor still requires overcoming several key technical challenges. One of the most critical issues is the harsh operating environment of SC-CO2-cooled nuclear reactors. According to domestic and international designs, these reactors typically operate at temperatures between 450°C and 650°C, with pressures ranging from 15 to 20 MPa. Although CO₂ is chemically inactive at low temperatures, it exhibits strong corrosive properties under the high temperatures of operational conditions. Even relatively low oxygen and carbon activities can still lead to oxidation and carbonization of the alloy, manifesting as the growth of an oxide layer on the surface and carburization of the matrix beneath it, respectively. This further degrades the material's heat transfer capacity and mechanical properties. More importantly, the coupled effects of mechanical stress and chemical corrosion significantly reduce the alloy's load-bearing capacity, significantly shortening the service life of structural alloys in reactors. Therefore, stress corrosion cracking (SCC) is considered a major challenge for cladding materials in the long-term service of high-temperature, SC-CO₂ corrosive environments. Among the many materials used in nuclear reactor equipment and components, the fuel element cladding, serving as the primary safety barrier enclosing the nuclear fuel, is subject to long-term corrosion and stress corrosion from coolant erosion in high-temperature, high-pressure environments. Furthermore, the cladding material must be extremely thin, only 0.3 to 0.7 mm. This unique thin-walled structure necessitates extremely high design standards for the core cladding material.

[0003] The current range of materials available for supercritical CO2 Brayton cycle systems primarily derives from materials used in supercritical and ultra-supercritical thermal power plants and high-temperature, high-pressure chemical equipment, primarily ferritic / martensitic steels (F / M steels), (super) austenitic stainless steels, and nickel-based alloys. Existing research results indicate that F / M steels exhibit rapid corrosion rates in supercritical CO2 environments. In particular, after exposure to SC-CO2, they form a multi-layered Fe-rich oxide film on their surface, which offers poor protection and can easily lead to severe carburization in the matrix beneath the film. Consequently, their mechanical properties are suboptimal at temperatures above 600°C, making them unsuitable for fuel cladding. Nickel-based alloys have been shown to exhibit excellent corrosion resistance even at higher temperatures (>700°C) in SC-CO2 environments, with the highest high-temperature creep performance. Among these, Inconel alloys 600 and 690 are widely used in steam generator heat transfer tube components for pressurized water reactors. Nickel-based alloys such as Inconel alloys 617, 625, and 718, with their superior corrosion resistance and mechanical strength, are ideal materials for key components in new nuclear power plants. However, the high cost of nickel-based alloys in recent years and their irradiation transmutation behavior make them difficult to be ideal candidates for fuel element cladding.

[0004] Austenitic stainless steel, with its face-centered cubic (FCC) crystal structure, offers excellent crystallographic stability and a lower atomic lattice diffusion rate than body-centered cubic (BCC) structures, resulting in improved high-temperature creep resistance. Furthermore, it can enhance the solid solubility of alloying elements, thereby improving other material properties. Cr, as the primary alloying element, provides austenitic stainless steel with excellent corrosion resistance. Although its corrosion resistance in high-temperature CO2 environments is slightly inferior to that of nickel-based alloys, its corrosion rate is nearly an order of magnitude slower than that of F / M steel. Furthermore, austenitic stainless steel exhibits excellent high-temperature mechanical properties, making it easy to form, weld, and fabricate complex components, all at a relatively low cost. Advanced gas-cooled reactors (AGRs) utilize Fe-20Cr-25Ni austenitic stainless steel (2025 steel). Its performance has been extensively verified, making it a promising structural material for SC-CO2-cooled nuclear reactors. Therefore, by focusing on the uniform corrosion and stress corrosion mechanisms of the material and through composition design, a new austenitic stainless steel material with excellent corrosion resistance and stress corrosion cracking resistance is prepared based on 2025 steel. Summary of the Invention

[0005] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

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

[0007] Therefore, the object of the present invention is to overcome the deficiencies in the prior art and provide an austenitic stainless steel resistant to corrosion and stress corrosion cracking in supercritical carbon dioxide and a method for preparing the same.

[0008] To solve the above technical problems, the present invention provides the following technical solutions: an austenitic stainless steel resistant to corrosion and stress corrosion cracking in supercritical carbon dioxide, characterized in that: the novel corrosion and stress corrosion cracking resistant austenitic stainless steel contains nickel, chromium, manganese, silicon, nitrogen, carbon and iron;

[0009] Calculated by weight percentage of the raw materials, the mass fraction of nickel is 24-26%, the mass fraction of chromium is 19.5-20.5%, the mass fraction of manganese is 0.6-0.8%, the mass fraction of silicon is 0.5-0.7%, the mass fraction of niobium is 0.5-0.7%, the mass fraction of nitrogen is 0.06-0.08%, the mass fraction of carbon is 0.02-0.05%, and the balance is Fe.

[0010] As a preferred embodiment of the austenitic stainless steel resistant to corrosion and stress corrosion cracking in supercritical carbon dioxide according to the present invention, the mass fraction of the raw materials is 24.5-25.5%, the mass fraction of chromium is 20-20.5%, the mass fraction of manganese is 0.65-0.75%, the mass fraction of silicon is 0.655-0.65%, the mass fraction of niobium is 0.55-0.65%, the mass fraction of nitrogen is 0.06-0.10%, the mass fraction of carbon is 0.03-0.04%, and the balance is Fe

[0011] As a preferred embodiment of the austenitic stainless steel resistant to corrosion and stress corrosion cracking in supercritical carbon dioxide according to the present invention, the mass fraction of nickel, chromium, manganese, silicon, niobium, nitrogen, carbon, and the remainder is Fe, calculated based on the mass percentage of the raw materials.

[0012] As a preferred embodiment of the austenitic stainless steel resistant to corrosion and stress corrosion cracking in supercritical carbon dioxide of the present invention, the novel austenitic stainless steel resistant to corrosion and stress corrosion cracking also has the following characteristics:

[0013] (i) The weight gain after oxidation in supercritical carbon dioxide at 650°C for 1000 hours is less than 30 mg / dm 2 ;

[0014] (ii) The time to failure under a constant load of 0.9Ys (yield strength) in supercritical carbon dioxide at 650°C is greater than 500 hours;

[0015] (iii) In supercritical carbon dioxide at 650°C, K (stress intensity factor) is maintained at 20 MPa·m 0.5 Under the action of -7 mm / s.

[0016] Another object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing austenitic stainless steel that is resistant to corrosion and stress corrosion cracking in supercritical carbon dioxide.

[0017] As a preferred embodiment of the preparation method of the present invention, pure metal raw materials Fe, Cr, Ni, and Nb are fully mixed according to the designed composition in a vacuum induction furnace, placed in a crucible, and evacuated and electrically melted; during the melting process, a high vacuum environment and a low melting rate are used to enhance carbon deoxidation and nitrogen removal efficiency; after the steel is liquefied and cleared, the remainder of C is added, and CrN is also added to introduce N, and the steel is fully melted before refining;

[0018] After refining, argon is introduced into the induction furnace, and Si and Mn are added to further reduce the oxygen and sulfur content, and then cast into steel ingots;

[0019] The smelted steel ingot is forged and then air-cooled to obtain a stainless steel forging blank, which is then polished to remove the oxide scale.

[0020] The stainless steel forging blank with oxide scale removed is heat treated to obtain a new type of corrosion-resistant and stress corrosion cracking resistant austenitic stainless steel.

[0021] As a preferred embodiment of the preparation method of the present invention, during the forging process, the steel ingot is placed in a heating furnace, heated to 1200°C at a heating rate of 120°C / h, kept warm for 3-8 hours, and then forging begins. The final forging temperature is not lower than 925°C. After forging, the stainless steel billet is obtained by water cooling or air cooling.

[0022] As a preferred embodiment of the preparation method of the present invention, the refining condition is to keep the temperature at 1500°C for not less than 10 minutes.

[0023] As a preferred embodiment of the preparation method of the present invention, the heat treatment conditions are as follows: the stainless steel forging blank is solution treated at 1100-1200°C for 60-120 minutes, water-cooled, and then aged at 650-700°C for 100 hours.

[0024] As a preferred embodiment of the preparation method of the present invention, the vacuum power transmission smelting conditions are 1550-1800° C. and the power transmission power is 5-40 kW.

[0025] As a preferred embodiment of the preparation method of the present invention, the starting forging temperature is not lower than 1150°C and not higher than 1245°C, and the final forging temperature is 900-1050°C.

[0026] Another object of the present invention is to overcome the deficiencies in the prior art and provide a new type of corrosion-resistant and stress corrosion cracking-resistant austenitic stainless steel for use in supercritical carbon dioxide cooled nuclear reactor cladding materials.

[0027] Beneficial effects of the present invention:

[0028] (1) The present invention aims at the long-term service performance requirements of the cladding material of the supercritical carbon dioxide cooled nuclear reactor. Through reasonable composition design, the content and ratio of each element in the alloy are adjusted, and heat treatment and other processes are used to obtain a new nitrogen-containing austenitic stainless steel. The material has the ability to resist high-temperature lead-bismuth and supercritical carbon dioxide corrosion.

[0029] (2) The new austenitic stainless steel of the present invention has good high-temperature corrosion resistance and stress corrosion cracking resistance in supercritical carbon dioxide: the weight gain after oxidation in supercritical carbon dioxide at 650°C for 1000 hours is less than 30 mg / dm 2 , the corrosion rate is extremely low; the fracture failure time under the constant load of 0.9Ys (yield strength) in supercritical carbon dioxide at 650℃ is higher than 500 hours, the creep resistance is good, and the threshold of stress corrosion crack initiation is high; in supercritical carbon dioxide at 650℃, K (stress intensity factor) is maintained at 20MPa·m 0.5 Under the action of -7 mm / s, and the stress corrosion crack growth rate is low. This material can meet the requirements for corrosion resistance and stress corrosion cracking performance in a 650℃ / 15MPa supercritical carbon dioxide environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0031] Figure 1 Corrosion weight gain curves of nitrogen-containing austenitic stainless steel provided in an embodiment of the present invention and 2025 steel of a comparative example in 650°C / 15MPa supercritical carbon dioxide for 1000h.

[0032] Figure 2Time-strain curves of the nitrogen-containing austenitic stainless steel provided in the embodiment of the present invention and the comparative example 2025 steel under a constant load of 0.9Ys (yield strength) in 650°C / 15MPa supercritical carbon dioxide.

[0033] Figure 3 The nitrogen-containing austenitic stainless steel provided in the embodiment of the present invention and the comparative example 2025 steel were subjected to K (stress intensity factor) at 20 MPa·m in 650°C / 15 MPa supercritical carbon dioxide. 0.5 Crack growth curve under the action of .

[0034] Figure 4 This is a conceptual diagram of a supercritical carbon dioxide corrosion / stress corrosion testing device according to an embodiment of the present invention.

[0035] Figure 5 This is a physical picture of the supercritical carbon dioxide corrosion / stress corrosion test device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0037] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0038] Secondly, the term "one embodiment" or "embodiment" 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 various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0039] Unless otherwise specified, the raw materials used in the examples of the present invention are commercially available.

[0040] Example 1

[0041] The present invention provides a method for preparing austenitic stainless steel that is resistant to corrosion and stress corrosion cracking in supercritical carbon dioxide:

[0042] Calculated by mass, it includes the following components: 25% Ni, 20% Cr, 0.7% Mn, 0.6% Si, 0.6% Nb, 0.07% N, 0.04% C, and the balance is Fe.

[0043] (1) Using a vacuum induction furnace, pure metal raw materials Fe, Cr, Ni, and Nb are mixed and placed in a crucible, vacuumed, and then smelted with electricity. The smelting temperature is 1500°C, and the holding time is not less than 10 minutes. After the steel is liquefied and cleared, C and Al are added and fully melted before refining.

[0044] (2) After refining, 0.04 MPa argon is introduced into the induction furnace, and Si and Mn are added to further reduce the oxygen and sulfur content. The steel is then cast into ingots.

[0045] (3) The smelted steel ingot is formed by forging. During the forging process, the steel ingot is placed in a heating furnace and first heated to 800℃ at a heating rate of 100℃ / h, and kept at the same temperature for 1-2h. Then, it is heated to 1200℃ at a heating rate of 100℃ / h, kept at this temperature for 3 hours, and then cooled to 1180℃. After keeping at this temperature for 1 hour, forging begins. The starting forging temperature is not lower than 1180℃ and not higher than 1250℃. The final forging temperature is 950-1000℃. The stainless steel forging blank is obtained by air cooling and polishing to remove the oxide scale.

[0046] The heat treatment process is as follows: the stainless steel forging blank is solution treated at 1150℃ for 60 minutes, water cooled, and then aged at 650℃ for 100 hours.

[0047] Example 2

[0048] The difference from Example 1 is that, by mass fraction, it includes the following components: 25% Ni, 20% Cr, 0.7% Mn, 0.6% Si, 0.6% Nb, 0.12% N, 0.04% C, and the balance is Fe.

[0049] Example 3

[0050] The difference from Example 1 is that, by mass fraction, it includes the following components: 25% Ni, 20% Cr, 0.7% Mn, 0.6% Si, 0.6% Nb, 0.04% N, 0.04% C, and the balance is Fe.

[0051] Comparative Example 1

[0052] The difference from Example 1 is that, by mass fraction, it includes the following components: 25% Ni, 20% Cr, 0.7% Mn, 0.6% Si, 0.6% Nb, 0.04% C, and the balance is Fe.

[0053] Comparative Example 2

[0054] The difference from Example 1 is that, by mass fraction, it includes the following components: 25% Ni, 20% Cr, 0.7% Mn, 1% Si, 0.6% Nb, 0.04% C, and the balance is Fe.

[0055] Comparative Example 3

[0056] The difference from Example 1 is that, by mass fraction, it includes the following components: 25% Ni, 20% Cr, 0.7% Mn, 0.6% Nb, 0.04% C, and the balance is Fe.

[0057] Comparative Example 4

[0058] The difference from Example 1 is that, by mass fraction, it includes the following components: 25% Ni, 20% Cr, 0.6% Si, 0.6% Nb, 0.04% C, and the balance is Fe.

[0059] Comparative Example 5

[0060] The difference from Example 1 is that, by mass fraction, it includes the following components: 25% Ni, 20% Cr, 1.2% Mn, 0.6% Si, 0.6% Nb, 0.04% C, and the balance is Fe.

[0061] Comparative Example 6

[0062] The difference from Example 1 is that, by mass fraction, it includes the following components: 25% Ni, 20% Cr, 1.2% Mn, 1% Si, 0.6% Nb, 0.07% N, 0.04% C, and the balance is Fe.

[0063] Comparative Example 7

[0064] The difference from Example 1 is that, by mass fraction, it includes the following components: 25% Ni, 20% Cr, 0.6% Nb, 0.07% N, 0.04% C, and the balance is Fe.

[0065] The materials used are shown in Table 1.

[0066] Table 1

[0067]

[0068]

[0069] Use as Figure 4 、 5The supercritical carbon dioxide corrosion / stress corrosion test apparatus shown is used to hang and fix the uniform corrosion specimens and stress corrosion specimens of the embodiment and comparative example on a specimen rack or a special fixture in an autoclave, respectively, and conduct corrosion and stress corrosion tests in supercritical carbon dioxide at 650°C and 15MPa. In the uniform corrosion test, the sampling nodes for weight gain and weighing are set to 100h, 300h, 500h, 700h, and 1000h, respectively. After each test, the samples are carefully removed, washed with alcohol, and oven-dried for at least 4 hours before being weighed. Except for retaining some samples for further analysis, the remaining samples are put back to continue the test until the final sampling is completed. In the constant load crack initiation test, the tensile machine control is turned on after determining that the system temperature and pressure conditions have reached the preset values. The tensile machine is used to control the stress to 0.9 times the yield strength of the corresponding material until the sample breaks and the experiment is terminated. In the stress corrosion crack growth experiment, a tensile machine was used to perform a reciprocating stretching-contraction motion on the specimen to induce fatigue cracks. The stress intensity factor K at the crack tip was then controlled to a constant value. The DCPD system was then used to monitor the crack length of the CT specimen in real time. The corrosion resistance of the design was evaluated by weight gain through supercritical carbon dioxide corrosion. The design's resistance to stress corrosion cracking was evaluated through constant load crack initiation and crack growth experiments. The results are shown in Table 2:

[0070] Table 2

[0071]

[0072]

[0073] As shown in Table 2, by controlling the trace elements of the alloy to obtain a multi-component embodiment, and screening the best strengthening method, the embodiment 1 with the best corrosion resistance, creep resistance and stress corrosion cracking resistance in a 650°C / 15MPa supercritical carbon dioxide environment was obtained. Figure 1 It can be seen that Example 1 has the lowest corrosion weight gain in 650°C / 15MPa supercritical carbon dioxide within a 1000-hour experimental period, indicating that the material has strong resistance to supercritical carbon dioxide corrosion and the formed oxide film has strong protective properties, preventing further oxidation weight gain of the material. Figure 2 The time-strain curves of the nitrogen-containing austenitic stainless steel provided in Example 1 of the present invention and the comparative example under a constant load of 0.9Ys (yield strength) in 650°C / 15MPa supercritical carbon dioxide are shown. The experimental results show that the fracture failure time of the example is as long as 637 hours, which is much longer than the 83 hours of the comparative example 1. This shows that the example has better creep performance and is more resistant to stress corrosion crack initiation in supercritical carbon dioxide. The doping of a reasonable content of nitrogen (0.06-0.08%) has a positive effect on the material's resistance to stress corrosion crack initiation in supercritical carbon dioxide. Figure 3The crack growth test results of nitrogen-containing austenitic stainless steel provided by the embodiment of the present invention and the comparative example in 650℃ / 15MPa supercritical carbon dioxide are shown in FIG. 0.5 Under the influence of the stress intensity factor, the crack growth rate of the embodiment is significantly superior to that of the comparative example, indicating that the embodiment is more resistant to stress corrosion cracking in supercritical carbon dioxide. Doping with a reasonable content of nitrogen (0.06-0.08%) has a positive effect on the material's resistance to stress corrosion crack growth in supercritical carbon dioxide.

[0074] 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 the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, and all of these should be included in the scope of the present invention.

Claims

1. An austenitic stainless steel resistant to corrosion and stress corrosion cracking in supercritical carbon dioxide, characterized by: Contains nickel, chromium, manganese, silicon, niobium, nitrogen, carbon and iron; Calculated by weight percentage of the raw materials, the mass fraction of nickel is 24-26%, the mass fraction of chromium is 19.5-20.5%, the mass fraction of manganese is 0.6-0.8%, the mass fraction of silicon is 0.5-0.7%, the mass fraction of niobium is 0.5-0.7%, the mass fraction of nitrogen is 0.04-0.12%, the mass fraction of carbon is 0.02-0.05%, and the balance is Fe.

2. The austenitic stainless steel resistant to corrosion and stress corrosion cracking in supercritical carbon dioxide according to claim 1, characterized in that: Calculated by weight percentage of the raw materials, the mass fraction of nickel is 24.5-25.5%, the mass fraction of chromium is 20-20.5%, the mass fraction of manganese is 0.65-0.75%, the mass fraction of silicon is 0.655-0.65%, the mass fraction of niobium is 0.55-0.65%, the mass fraction of nitrogen is 0.06-0.10%, the mass fraction of carbon is 0.03-0.04%, and the balance is Fe.

3. The austenitic stainless steel resistant to corrosion and stress corrosion cracking in supercritical carbon dioxide according to claim 2, characterized in that: Calculated by weight percentage of the raw materials, the mass fraction of nickel is 25%, the mass fraction of chromium is 20%, the mass fraction of manganese is 0.7%, the mass fraction of silicon is 0.6%, the mass fraction of niobium is 0.6%, the mass fraction of nitrogen is 0.07%, the mass fraction of carbon is 0.03%, and the balance is Fe.

4. The austenitic stainless steel resistant to corrosion and stress corrosion cracking in supercritical carbon dioxide according to claims 1 to 3, characterized in that: It also has the following features: (i) The weight gain after oxidation in supercritical carbon dioxide at 650°C for 1000 hours is less than 30 mg / dm 2 ; (ii) The time to failure under a constant load of 0.9Ys (yield strength) in supercritical carbon dioxide at 650°C is greater than 500 hours; (iii) In supercritical carbon dioxide at 650℃, the stress intensity factor is maintained at 20 MPa·m 0.5 Under the action of -7 mm / s.

5. The method for preparing the novel corrosion-resistant and stress corrosion cracking-resistant austenitic stainless steel according to claim 4, characterized in that: include, The pure metal raw materials Fe, Cr, Ni and Nb are mixed and then vacuumed and sent to electric melting. After the steel is liquefied and clear, C and CrN are added to melt and then refined; After refining, argon is introduced, Si and Mn are added, and then cast into steel ingots; After forging, the steel ingot is air-cooled to obtain a stainless steel forging blank, and then polished to remove the oxide scale to obtain a descaled stainless steel forging blank; The stainless steel forging blank with oxide scale removed is heat treated to obtain the austenitic stainless steel resistant to corrosion and stress corrosion cracking in supercritical carbon dioxide.

6. The preparation method according to claim 5, wherein: The forging conditions are heating to 1200° C. at a heating rate of 120° C. / h, keeping the temperature for 3 to 8 hours, the final forging temperature being not less than 925° C., and obtaining the stainless steel billet by water cooling or air cooling after forging.

7. The preparation method according to claim 5, wherein: The refining condition is to keep the temperature at 1500° C. for not less than 10 minutes.

8. The preparation method according to claim 5, wherein: The heat treatment conditions are as follows: the stainless steel forging blank is solution treated at 1100-1200° C. for 60-120 minutes, water-cooled, and then aged at 650-700° C. for 100 hours.

9. The preparation method according to claim 5, wherein: The vacuum power transmission smelting conditions are 1550-1800° C. and the power transmission power is 5-40KW.

10. The austenitic stainless steel resistant to corrosion and stress corrosion cracking in supercritical carbon dioxide as claimed in claim 1 is used as a cladding material in a supercritical carbon dioxide cooled nuclear reactor.

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