Austenitic stainless steel for nuclear power plants resistant to stress corrosion and method for manufacturing the same

Abstract

The application discloses a stress corrosion resistant austenitic stainless steel for nuclear power and a manufacturing method thereof. The chemical composition of the steel comprises C: 0.06%-0.10%; Si: 0.85%-1.20%; Mn: 1.65%-2.25%; P≤0.015%; S≤0.005%; Ni: 8.45%-9.55%; Cr: 16.25%-18.45%; Al: 0.80%-1.50%; Mg: 0.002%-0.004%; Nb: 0.015%-0.030%; and Zn: 0.002%-0.005%. The production process of smelting, continuous casting, heating, rolling and heat treatment is combined, the yield strength and tensile strength of the steel plate at room temperature are above 420 MPa and 752 MPa respectively, the yield strength and tensile strength during high-temperature tension at 650 DEG C are above 205 MPa and 412 MPa respectively, and the steel plate has good intergranular corrosion resistance and stress corrosion resistance.

Description

Technical Field

[0001] This invention belongs to the field of metal materials technology, and particularly relates to a stress corrosion resistant austenitic stainless steel for nuclear power plants and its manufacturing method. Background Technology

[0002] Austenitic stainless steel is widely used in industry due to its good mechanical properties, machinability, corrosion resistance, and resistance to neutron radiation, accounting for more than 60% of the world's total stainless steel production.

[0003] The service environment for nuclear power plant metal materials is typically high-temperature, high-pressure water, accompanied by a certain degree of radiation. This harsh environment and prolonged exposure leave the structural materials of nuclear power plants susceptible to corrosion. Cracks in structural materials under the combined acceleration of corrosive media and stress in high-temperature, high-pressure water can initiate from localized defects, propagate, and eventually lead to complete cracking. Once cracks initiate, they rapidly propagate across the equipment materials, causing component failure, coolant leakage, and even unit shutdown, directly threatening the safe operation of the nuclear power plant. To improve the corrosion resistance of nuclear power equipment, nickel-based alloys and austenitic stainless steels, which possess good corrosion resistance and mechanical properties, are mostly selected for structural materials in water-cooled nuclear reactors. Their superior corrosion resistance primarily stems from the formation of a chromium-rich oxide film (passivation film) on the material surface in the corrosive medium. However, the carbon content in steel is generally low, resulting in relatively low strength, which hinders industry development and is a pressing technical problem that needs to be solved in this field.

[0004] The patent application CN201711132673.2, entitled "A Nitrogen-Controlled Austenitic Stainless Steel with Excellent Stress Corrosion Resistance," has the following composition by weight percentage: 0.01% ≤ C ≤ 0.04%, 0.06% ≤ N ≤ 0.16%, 0.001% ≤ Si ≤ 0.080%, Mn ≤ 2.0%, 0.001% ≤ P ≤ 0.015%, S ≤ 0.005%, 17.0% ≤ Cr ≤ 25.0%, 8.0% ≤ Ni ≤ 25.0%, Mo ≤ 3.5%, with the balance being Fe. The alloy also contains other residual elements and elements that improve hot working properties, such as O, Ca, Ti, Nb, B, La, Ce, Al, Zr, V, Mg, Cu, Co, and B. Its advantage lies in avoiding the problem of reduced stress corrosion resistance caused by low-temperature sensitization in existing nitrogen-controlled austenitic stainless steels; this nitrogen-controlled austenitic stainless steel exhibits excellent stress corrosion resistance. The invention designs the upper limit of carbon content in steel plates to be 0.04%, but does not address the performance of austenitic stainless steel plates with higher carbon content.

[0005] The patent application CN201811296546.0, entitled "Austenitic Stainless Steel and its Preparation Method and Application," includes the following composition by mass percentage: C 0.04%-0.08%, Cr 16.5%-20.0%, Ni 14.5%-16.5%, Si 1.0%-3.0%, Mn 1.5%-3.0%, Ti 0.2%-0.5%, Mo 1.3%-2.5%, B 0.003%-0.004%, with the balance being Fe. The austenitic stainless steel of this invention exhibits higher room temperature and medium temperature tensile strength, excellent plasticity, and increased alloy strength after medium temperature aging treatment without significant reduction in plasticity, no harmful phase precipitation, and good microstructural stability. It also possesses excellent resistance to lead and lead-bismuth liquid metal corrosion and radiation resistance, better meeting the material selection requirements for key components of lead-based fast reactors. However, the cost of die casting and forging is high, the yield is low, and the finished products obtained by this invention are small in size, making them unsuitable for industrial production. At the same time, it cannot guarantee resistance to stress corrosion. Summary of the Invention

[0006] The purpose of this invention is to provide a stress corrosion resistant austenitic stainless steel for nuclear power and its manufacturing method. By designing an alloy composition and using an appropriate process, the stress corrosion resistance of the steel plate and the mechanical properties of nuclear power steel are taken into account, so that it has both stress corrosion resistance and excellent tensile properties.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A stress corrosion resistant austenitic stainless steel for nuclear power plants, comprising, by weight percentage: C: 0.06%-0.10%; Si: 0.85%-1.20%; Mn: 1.65%-2.25%; P≤0.015%; S≤0.005%; Ni: 8.45%-9.55%; Cr: 16.25%-18.45%; Al: 0.80%-1.50%; Mg: 0.002%-0.004%; Nb: 0.015%-0.030%; Zn: 0.002%-0.005%; with the balance being Fe and unavoidable impurities.

[0009] Furthermore, the chemical composition of stainless steel is as follows: Ni+Cr: 25%-27%; Al+Cr+Si: 18.5%-20.5%; Zn+Mg: ≥0.005%.

[0010] Furthermore, the thickness of stainless steel plates ranges from 10 to 100 mm.

[0011] Furthermore, the room temperature yield strength R of stainless steel p0.2 Achieved tensile strength R of over 420 MPa mThe yield strength reaches over 752 MPa; under high temperature tensile stress at 650℃, the yield strength R p0.2 Achieve a tensile strength of 205 MPa or higher, R m It reaches over 412 MPa.

[0012] Furthermore, after sensitization treatment at 650℃ for 2 hours followed by air cooling, an intergranular corrosion test was conducted in a 65% nitric acid solution for 240 hours. The corrosion rate of the stainless steel was ≤0.305 g / m. 2 ·h.

[0013] Furthermore, the test solution was a 3.5% NaCl solution, the pH was adjusted to 2 with hydrochloric acid, the test temperature was 50℃, and the strain rate was 10. -6 The stress corrosion susceptibility index of stainless steel is ≤13.5%.

[0014] A method for manufacturing stress corrosion resistant austenitic stainless steel for nuclear power plants, the production process including: smelting, continuous casting, heating, rolling, and heat treatment, wherein...

[0015] Heating: The billet is heated as it is loaded into the furnace, with a heating temperature of 1230-1280℃ and a holding time of 5-6 hours in the soaking zone;

[0016] Rolling: Rolling adopts a two-stage controlled rolling process. The first stage starts at a rolling temperature of 1130-1180℃, with the average reduction rate of the first three passes controlled at 20%-25%, the roll speed at 2.5-4.0 m / s, and the final rolling temperature controlled at ≥1050℃. The second stage starts at a rolling temperature of 1030-1050℃, with the last five passes using small deformation, an average reduction rate of 5%-7%, and a final rolling temperature at ≥1000℃. The steel plate undergoes laminar flow cooling treatment with a maximum cooling rate of 25℃ / s and a final cooling temperature of 450-600℃.

[0017] Heat treatment: Perform solution heat treatment at 1100-1140℃ for 0.5-4.5h, and water cool to room temperature after removing from the furnace; then, perform stabilization annealing treatment, put the furnace at room temperature, heat it to 880-900℃ with the furnace, hold for 1-2h, and air cool to room temperature after removing from the furnace.

[0018] Furthermore, the smelting process employs an induction furnace + LF + RH. The induction furnace uses industrial pure iron and alloys to complete the melting and composition adjustment. The induction furnace tapping temperature is ≥1640℃. The LF controls sulfur and removes inclusions. The RH performs vacuum treatment on the molten steel, with a vacuum degree of ≤0.2kPa.

[0019] Furthermore, the continuous casting temperature is controlled at 1480-1500℃.

[0020] Furthermore, the thickness of the continuously cast billet is 200-300mm, and the billets are stacked and slowly cooled for more than 48 hours immediately after being cast off the production line.

[0021] In terms of composition design, this invention, based on a low-carbon composition, simultaneously adds Nb, Mg, and Zn to strengthen the steel through a combined effect. In particular, increasing the Al content significantly improves the steel's high-temperature performance and stress corrosion resistance, and enhances the passivation ability of stainless steel. Combined with the smelting-continuous casting-heating-rolling-heat treatment production process, this ensures the steel plate has excellent room temperature and high-temperature properties, with good key indicators, fully meeting the requirements of subsequent equipment manufacturing. The steel grade of this invention, after heat treatment, exhibits a good strength level, with a room temperature yield strength (R0) of [missing value]. p0.2 ) and tensile strength (R m The yield strength (R) reached over 420 MPa and 752 MPa respectively; at a high temperature of 650℃, the yield strength (R) was... p0.2 ) and tensile strength (R m The pressures reached 205 MPa and 412 MPa respectively. After sensitization treatment at 650℃ for 2 hours and air cooling, intergranular corrosion was conducted in a 65% nitric acid solution for 240 hours, with a corrosion rate ≤0.305 g / m. 2 •h. The test solution was a 3.5% NaCl solution, with the pH adjusted to 2 using hydrochloric acid. The test temperature was 50℃, and the strain rate was 10. -6 The stress corrosion sensitivity index (SCR) is ≤13.5%, indicating that the nuclear power steel exhibits excellent resistance to intergranular corrosion and stress corrosion. The nuclear power austenitic stainless steel of this invention combines high strength and toughness, corrosion resistance, high-temperature performance, and an efficient and economical production process. Furthermore, the process is simple and stable, with low requirements for rolling conditions, low rolling costs, and strong operability, making it more suitable for various application fields. Detailed Implementation

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other. The described embodiments are merely some, not all, of the embodiments of this invention. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0023] This invention provides a stress corrosion resistant austenitic stainless steel for nuclear power plants, the chemical composition of which is as follows by weight percentage: C: 0.06%-0.10%; Si: 0.85%-1.20%; Mn: 1.65%-2.25%; P≤0.015%; S≤0.005%; Ni: 8.45%-9.55%; Cr: 16.25%-18.45%; Al: 0.80%-1.50%; Mg: 0.002%-0.004%; Nb: 0.015%-0.030%; Zn: 0.002%-0.005%; Ni+Cr: 25%-27%; Al+Cr+Si: 18.5%-20.5%; Zn+Mg: ≥0.005%; the balance being Fe and unavoidable impurities.

[0024] The reasons for using the above-mentioned components are as follows:

[0025] Carbon (C): It can significantly improve the strength of steel through solid solution treatment, making it the most fundamental strengthening element in steel. It has a significant impact on the yield strength, tensile strength, and weldability of steel. Some C in steel enters the steel matrix, causing solid solution strengthening, while another portion combines with carbide-forming elements in alloys to form alloy carbides. However, excessive C content can cause various negative effects, such as a decrease in the weldability and corrosion resistance of steel. Based on the application requirements and performance specifications, this invention selects a C content of 0.06%-0.10%.

[0026] Si (Si): In the steelmaking process, it acts as a reducing agent and deoxidizer, and also plays a role in solid solution strengthening. Simultaneously, it improves the oxidation resistance and high-temperature corrosion resistance of steel plates. Si can also form a SiO2 passivation film on the steel surface, and simultaneously form a composite passivation film with Cr2O3, which can significantly improve the corrosion resistance of steel. However, excessive Si, when used in high-temperature environments for extended periods, is detrimental to the toughness of the steel plate, leading to brittleness in the weld fusion zone. Considering all factors, the Si content in this invention is selected within the range of 0.85%-1.20%.

[0027] Mn (Nitrogen): Mn can enhance the strength of steel through solid solution strengthening, compensating for the deficiencies caused by reduced carbon (C). It is a major alloying element affecting strength, hardenability, and weldability, and is also inexpensive. However, excessive Mn content negatively impacts toughness and high-temperature performance, and easily leads to segregation, resulting in uneven composition and microstructure of the matrix material. This invention adds an appropriate amount of Mn to stabilize austenite, allowing more carbides to dissolve into the matrix during high-temperature solid solution treatment and combine with other strong carbide elements to form carbides, maximizing their beneficial effects. Simultaneously, it avoids adverse effects on the material's toughness and resistance to thermal fatigue. Therefore, this invention selects an Mn content of 1.65%-2.25%.

[0028] P and S are both harmful elements in the steel of this invention, which adversely affect the low-temperature impact toughness of the steel plate and increase its brittleness; sulfur reduces the ductility and toughness of the steel and causes cracks during rolling. Therefore, the lower the content, the better. However, considering steelmaking conditions and costs, this invention requires that P be controlled to ≤0.015% and S to ≤0.005% in the steel.

[0029] Ni: A major synthetic element in stainless steel. Adding an appropriate amount of Ni helps to obtain a single-phase austenitic structure, significantly improving corrosion resistance and plasticity. Within a certain temperature range, Ni can also interact with Cr to form a well-protected spinel oxide film, such as the NiO·Cr2O3 composite oxide film, effectively improving the steel's corrosion resistance and high-temperature oxidation resistance. However, excessive Ni will increase costs and reduce the diffusion rate of carbon in the matrix, delaying the dissolution of undissolved carbides into austenite and reducing strength. Therefore, this invention sets its content at 8.45%-9.55%.

[0030] Cr (Cr): This is the main element determining the corrosion resistance of stainless steel. Generally, corrosion resistance and oxidation resistance increase with increasing Cr content. However, with increasing Cr content, the precipitation of intermetallic compounds such as the G phase accelerates, increasing the steel's brittleness and raising the brittle transition temperature. Furthermore, passivation by Cr alone is insufficient to maintain corrosion resistance; elements that inhibit anodic dissolution, such as Ni and Si, need to be added in combination with Cr to significantly improve the corrosion resistance of stainless steel. Therefore, this invention designs the Cr content to be 16.25%-18.45%.

[0031] Al (Al) is a ferrite-forming element that prevents the segregation of elements such as S, P, Si, and Nb, and the formation of low-melting-point eutectics, thus preventing hot cracking. Al also possesses antioxidant and anti-corrosion properties. When used in combination with Cr and Si in steel, it can significantly improve the high-temperature performance and stress corrosion resistance of the steel. Furthermore, the addition of Al transforms the original single-phase austenite structure into a two-phase structure, lowering the interfacial energy compared to single-phase austenite. This increases the diffusion rate of Cr atoms by about two orders of magnitude compared to when Al is not added, compensating for chromium depletion and ensuring the durability of the passivation film. The addition of Al also consumes some C atoms, hindering C diffusion to grain boundaries and providing a certain shielding effect, reducing the formation of chromium carbide at grain boundaries and mitigating chromium depletion. Therefore, compared to traditional chromium oxide films, alumina films exhibit better density and stability, resulting in significantly improved corrosion resistance. However, as its content increases, a large amount of ferrite will be formed, which will significantly reduce the mechanical properties and creep resistance of the steel. Therefore, the Al content range of this invention is 0.80%-1.50%.

[0032] Mg (Mg) can reduce the number, size, and uniform distribution of inclusions in steel, and improve their morphology. In this invention, due to the high Al content, the appropriate addition of Mg refines the non-metallic inclusions in the steel. Simultaneously, it improves the size and distribution of carbides in the steel, resulting in finer and more uniform carbide particles. This transforms continuous network carbides into isolated spheres, protecting the continuity of the steel, buffering stress concentration, and inhibiting crack formation. Furthermore, without affecting plasticity, it helps improve the tensile strength and yield strength of the steel. Therefore, the Mg content added in this invention is 0.002%-0.004%.

[0033] Nitrogen (Nb): In steel, Nb forms stable NbC or Nb4C3 and is finely dispersed in the matrix, playing a role in precipitation strengthening. Appropriate amounts of Nb can increase the strength of steel without affecting its plasticity or toughness. Due to its grain-refining effect, it can improve the impact toughness of steel and lower its brittle transition temperature. It can also prevent intergranular corrosion of steel by oxidizing media. Due to its carbon fixation and precipitation hardening effect, it can improve the high-temperature performance of steel. Considering cost factors, this invention selects an Nb content of 0.015%-0.030%.

[0034] Zn can improve the slip-drawing ability of the steel matrix phase, inhibit crack propagation, and reduce the crack sensitivity and notch sensitivity of the matrix phase. In addition, Zn works together with Al and Mg in the steel to significantly improve the corrosion resistance of the steel, enhance its oxidation resistance at high temperatures, hinder the diffusion of elements such as oxygen, reduce the depletion of alloying elements on the steel surface and at grain boundaries, and improve the stress corrosion resistance. Therefore, in this invention, Zn is added at 0.002%-0.005%.

[0035] The present invention discloses a method for manufacturing austenitic stainless steel for nuclear power plants resistant to stress corrosion. The steel plate production process is as follows: smelting—continuous casting—heating—rolling—heat treatment, as detailed below:

[0036] (1) Smelting and Continuous Casting: The smelting of molten steel is completed in three steps: induction furnace + LF + RH. The induction furnace uses industrial pure iron and alloys to melt and adjust the composition. The tapping temperature of the induction furnace is ≥1640℃. The LF controls sulfur and removes inclusions. The RH performs vacuum treatment on the molten steel with a vacuum degree of ≤0.2kPa to remove gases such as hydrogen, oxygen, and nitrogen. The casting temperature is controlled at 1480-1500℃ for continuous casting. The casting temperature is the key control point. Low-temperature casting is beneficial to refine the original as-cast structure. After the continuous casting billet comes off the line, it is immediately stacked and slowly cooled for more than 48 hours. The preferred thickness of the continuous casting billet is 200-300mm.

[0037] (2) Heating: The continuously cast billet is loaded into the furnace and heated to 1230-1280℃. The soaking time is 5-6 hours. The alloy content of this invention is relatively high, which is prone to segregation. Therefore, a higher billet heating temperature and a longer holding time are required to allow the alloying elements to fully dissolve in the matrix, improve the non-uniformity of the billet composition, and thus reduce subsequent microstructure segregation, avoiding performance inhomogeneity caused by microstructure segregation after rolling. A reasonable heating regime can lay the foundation for subsequent rolling and obtaining a good microstructure of the final steel plate.

[0038] (3) Rolling: The steel plate rolling adopts a two-stage controlled rolling process. The first stage has an initial rolling temperature of 1130-1180℃, using high-temperature, high-reduction rolling. The average reduction rate of the first three passes is controlled at 20%-25%. Increasing the initial rolling temperature promotes dynamic recrystallization and dynamic recovery, ensuring uniform grain size throughout the thickness of the steel plate. The roll speed is 2.5-4.0 m / s, and the final rolling temperature is controlled at ≥1050℃. The second stage has an initial rolling temperature of 1030-1050℃, and the last five passes use small deformation, with an average reduction rate of 5-7%. This helps to retain the orientation gradient of the hot-rolled state. Large deformation in the later stages can easily cause the already recrystallized grains to tend to have a uniform orientation, resulting in abnormal grain growth. The final rolling temperature is ≥1000℃. This is because the temperature range below 1000℃ is within the temperature range where continuous dynamic recrystallization and discontinuous dynamic recrystallization occur simultaneously. Both will leave behind recovery structures that have not undergone recrystallization, leading to grain growth, coarsening, and uneven grain size. After rolling, the steel sheet undergoes laminar flow cooling to suppress recovery and prevent further grain growth. The maximum cooling rate during laminar flow cooling is 25℃ / s, and the final cooling temperature is 450-600℃. The thickness of the rolled steel sheet is 10-100mm.

[0039] (4) Heat Treatment: To achieve a single-phase austenitic structure by filling and dissolving carbides and preserving them in austenite at room temperature, thus giving the steel the strongest corrosion resistance, a solution heat treatment is performed at 1100-1140℃ for 0.5-4.5 hours, followed by water cooling to room temperature after removal from the furnace. To further eliminate the chromium-depleted layer, improve the steel's corrosion resistance, and ensure uniform diffusion of alloying elements in austenite, a stabilization annealing treatment is adopted. The steel is placed in the furnace at room temperature, heated to 880-900℃, held for 1-2 hours, and then air-cooled to room temperature after removal from the furnace. This invention uses a slightly higher temperature than traditional annealing to increase the diffusion rate of alloying elements, thereby shortening the time the steel plate spends in the furnace and avoiding grain growth caused by excessive time.

[0040] A stress corrosion resistant austenitic stainless steel for nuclear power plants and its manufacturing method are described below:

[0041] Table 1 lists the components involved in each embodiment, Table 2 lists the production process parameters for each embodiment, and Table 3 lists the overall performance of each embodiment.

[0042] Table 1. Chemical composition (%) of steel smelting in each embodiment

[0043]

[0044] Table 2 Production process parameters for each embodiment

[0045]

[0046]

[0047] Table 3 shows the overall performance of each embodiment.

[0048]

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A stress corrosion resistant austenitic stainless steel for nuclear power plants, characterized in that, The chemical composition of the steel, by weight percentage, includes: C: 0.06%-0.10%; Si: 0.85%-1.20%; Mn: 1.65%-2.25%; P≤0.015%; S≤0.005%; Ni: 8.45%-9.55%; Cr: 16.25%-18.45%; Al: 0.80%-1.50%. Mg: 0.002%-0.004%; Nb: 0.015%-0.030%; Zn: 0.002%-0.005%; balance is Fe and unavoidable impurities.

2. The austenitic stainless steel for nuclear power plants resistant to stress corrosion according to claim 1, characterized in that, Ni+Cr: 25%-27%; Al+Cr+Si: 18.5%-20.5%; Zn+Mg: ≥0.005%.

3. The austenitic stainless steel for nuclear power plants resistant to stress corrosion according to claim 1, characterized in that, Stainless steel plates are 10-100mm thick.

4. The austenitic stainless steel for nuclear power plants resistant to stress corrosion according to claim 1, characterized in that, Room temperature yield strength R p0.2 Achieved tensile strength R of over 420 MPa m The yield strength reaches over 752 MPa; under high temperature tensile stress at 650℃, the yield strength R p0.2 Achieve a tensile strength of 205 MPa or higher, R m It reaches over 412 MPa.

5. The austenitic stainless steel for nuclear power plants resistant to stress corrosion according to claim 1, characterized in that, After sensitization treatment by air cooling at 650℃ for 2 hours, intergranular corrosion was conducted in a 65% nitric acid solution for 240 hours, with a corrosion rate ≤0.305 g / m. 2 ·h.

6. The austenitic stainless steel for nuclear power plants resistant to stress corrosion according to claim 1, characterized in that, The test solution was a 3.5% NaCl solution, with the pH adjusted to 2 using hydrochloric acid. The test temperature was 50℃, and the strain rate was 10. -6 s, stress corrosion susceptibility index ≤13.5%.

7. A method for manufacturing the stress corrosion resistant austenitic stainless steel for nuclear power plants as described in claim 1, the production process comprising: Smelting, continuous casting, heating, rolling, and heat treatment, characterized in that, Heating: The billet is heated as it is loaded into the furnace, with a heating temperature of 1230-1280℃ and a holding time of 5-6 hours in the soaking zone; Rolling: Rolling adopts a two-stage controlled rolling process. The first stage starts at a rolling temperature of 1130-1180℃, with the average reduction rate of the first three passes controlled at 20%-25%, the roll speed at 2.5-4.0 m / s, and the final rolling temperature controlled at ≥1050℃. The second stage starts at a rolling temperature of 1030-1050℃, with the last five passes using small deformation, the average reduction rate at 5%-7%, and the final rolling temperature at ≥1000℃. The steel plate undergoes laminar flow cooling treatment with a maximum cooling rate of 25℃ / s and a final cooling temperature of 450-600℃. Heat treatment: Perform solution heat treatment at 1100-1140℃ for 0.5-4.5h, and water cool to room temperature after removing from the furnace; then, perform stabilization annealing treatment, put the furnace at room temperature, heat it to 880-900℃ with the furnace, hold for 1-2h, and air cool to room temperature after removing from the furnace.

8. The method for manufacturing a stress corrosion resistant austenitic stainless steel for nuclear power plants according to claim 7, characterized in that, The smelting process employs an induction furnace + LF + RH. The induction furnace uses industrial pure iron and alloys to complete the melting and composition adjustment. The induction furnace tapping temperature is ≥1640℃. The LF controls sulfur and removes inclusions. The RH performs vacuum treatment on the molten steel, with a vacuum degree of ≤0.2kPa.

9. A method for manufacturing a stress corrosion resistant austenitic stainless steel for nuclear power plants according to claim 7, characterized in that, The continuous casting temperature is controlled at 1480-1500℃.

10. A method for manufacturing a stress corrosion resistant austenitic stainless steel for nuclear power plants according to claim 7, characterized in that, The thickness of the continuously cast billet is 200-300mm. After the billet comes off the production line, it is immediately stacked and slowly cooled for more than 48 hours.

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