Preparation method of XM-19 super austenitic stainless steel with high tensile strength

Abstract

The invention discloses a preparation method of XM-19 superaustenitic stainless steel with high tensile strength, which comprises the following steps: carrying out solution heat treatment at the temperature of 1060-1066 DEG C on an XM-19 stainless steel forge piece which is forged for multiple times to form uniform austenite grains, and sequentially carrying out water quenching to eliminate work hardening and multi-pass cold drawing work hardening to form a fiber structure, thereby obtaining the XM-19 superaustenitic stainless steel. According to the XM-19 stainless steel, the temperature of solid solution heat treatment is increased under the specific components to control the austenite grain size, and the multi-pass cold drawing machining technology is cooperated to enable grains to deform to form a fiber structure, so that the grain boundary is strengthened, and the strength and toughness of the XM-19 stainless steel are remarkably improved.

Description

Technical Field

[0001] The invention relates to a method for preparing XM-19 super austenitic stainless steel with high tensile strength, and belongs to the technical field of stainless steel material preparation. Background Art

[0002] XM-19 super austenitic stainless steel has important application value in harsh working conditions due to its excellent mechanical properties and good corrosion resistance. However, this material faces significant challenges in its actual preparation and application. Its processing difficulty is extremely high due to the high strength and high hardness of the material itself, which places stringent requirements on processing equipment and cutting tools, resulting in rapid tool wear, low processing efficiency and high cost; at the same time, it has a significant tendency to work hardening and is prone to hardening during cold working, which not only increases the difficulty of subsequent processing, but may also induce material embrittlement and reduce toughness, and often requires additional process annealing to eliminate stress. The hot working process is also extremely complex, requiring precise control of temperature and cooling rate to ensure performance, and it is difficult to remove the surface oxide scale after hot working. Alkaline soaking or shot blasting and other pretreatments are often required before pickling, further increasing the complexity and cost of the process.

[0003] In terms of service performance, while XM-19 exhibits excellent overall corrosion resistance, its corrosion resistance is limited in certain extreme environments (such as high-concentration corrosive media, environments containing chloride ions, and high-temperature and high-pressure conditions). Pitting and perforation or stress corrosion cracking may occur, threatening the safe operation of equipment. Furthermore, in the presence of hard particles or high-velocity fluids, it is susceptible to abrasive and erosive wear, impacting equipment precision and performance. High- and low-cycle fatigue failures may occur in components subjected to alternating loads. Under long-term high-temperature service, it faces creep deformation and high-temperature oxidation, reducing component dimensional stability and service life. These failure modes limit its reliable application in more demanding environments.

[0004] On the other hand, XM-19 material costs are relatively high, primarily due to its high proportion of precious alloying elements such as nickel and chromium. This results in high prices for both the raw materials and the final product, which, to a certain extent, restricts its widespread application in cost-sensitive fields. In summary, existing XM-19 stainless steel suffers from significant deficiencies in processing manufacturability (difficulty, severe hardening, and stringent thermal processing control), service reliability (inadequate corrosion resistance, wear resistance, fatigue resistance, and high-temperature performance in harsh environments), and affordability. Therefore, the development of a new preparation method aims to optimize the matching of formulation design and heat treatment process, significantly improve its processing performance (especially reducing the tendency to work hardening and simplifying the thermal processing process), simultaneously enhance its tensile strength and comprehensive service performance in complex environments (including corrosion resistance, wear resistance, fatigue resistance, and high-temperature stability), while also taking into account cost-effectiveness. This has become an inevitable choice to meet the urgent demand for high-performance stainless steel in the high-end equipment field. Summary of the Invention

[0005] In response to the shortcomings of XM-19 stainless steel in the prior art, such as low tensile strength and poor toughness, the present invention aims to provide a method for preparing XM-19 super austenitic stainless steel with high tensile strength. By increasing the temperature of the solid solution heat treatment under specific composition, controlling the austenite grain size, and coordinating a multi-pass cold drawing process to deform the grains into fibrous structure and strengthen the grain boundaries, the strength and toughness of XM-19 stainless steel are significantly improved.

[0006] To achieve the above technical objectives, the present invention provides a method for preparing XM-19 super austenitic stainless steel with high tensile strength. The method comprises the following steps: subjecting XM-19 stainless steel forgings that have undergone multiple forgings to a solution heat treatment at a temperature of 1060-1066°C to form uniform austenite grains, and then subjecting the forgings to water quenching to eliminate work hardening and multiple cold drawing processes to form a fibrous structure. The conditions for the multiple cold drawing processes are as follows: a single-pass deformation of 1.5-2.5%, a cold drawing rate of 1-2 mm / s, a total deformation of 10-15%, a single-pass temperature return to 60-80°C for 0.5-1 hour at intervals of 1-2 hours, and a stress relief annealing treatment at 200-220°C after each pass.

[0007] The key to the technical solution of this invention lies in the formation of uniform austenite grains at high solution heat treatment temperatures, combined with a cold drawing process, to simultaneously enhance the tensile strength and toughness of XM-19. Specifically, given the selected XM-19 composition, high solution heat treatment temperatures dissolve carbides and γ' phase (precipitation strengthening) within the matrix to produce a uniform, supersaturated solid solution. This facilitates the reprecipitation of finely divided carbides and strengthening phases such as γ' during water quenching, while simultaneously eliminating stresses generated by hot and cold working and allowing the alloy to recrystallize. Secondly, solution treatment is performed to achieve an appropriate grain size to ensure the alloy's high-temperature creep resistance. Furthermore, high temperatures release the pinning of second-phase particles (Nb / V carbonitrides) on grain boundaries, unleashing the potential for grain growth. Rapid cooling stabilizes the coarse-grained structure, further refining the austenite grain size. After solid solution, the austenite grains are uniform. At this time, through cold drawing, the grains are elongated along the deformation direction to form a fibrous structure. The superposition of grain boundary strengthening and work hardening is used to significantly improve the tensile strength and toughness of XM-19.

[0008] The selection of the temperature range for the solution heat treatment of the present invention is based on the matching considerations of the contents of Cr, Ni, Mo, Nb and V in the composition of XM-19 stainless steel and microstructure control. When the temperature is too low, the second phase particles such as carbides and Nb / V carbonitrides in the matrix cannot be completely dissolved. These undissolved hard and brittle phases will become stress concentration points and will pin the grain boundaries, hindering the uniform growth of grains, resulting in insufficient and uneven refinement of austenite grains. During cold drawing, deformation is concentrated in the fine grain area, which is prone to local cracking and reduces the tensile strength. When the temperature is too high, it will cause excessive coarsening of austenite grains (grain size less than level 6), reduce the total area of ​​grain boundaries, and weaken the grain boundary strengthening effect. At the same time, high temperature will promote the segregation of elements such as Cr and Mo, increase the anisotropy during subsequent cold drawing, and reduce the toughness and strength synergy of the material.

[0009] Experiments have shown that the reheating process during the cold drawing process significantly impacts the overall performance of XM-19 stainless steel. During cold drawing, the material generates significant heat due to plastic deformation. Performing only post-pass stress relief annealing without reheating can lead to localized overheating, reducing the efficiency of dislocation density accumulation and weakening the work hardening effect. Furthermore, the temperature distribution in the deformation zone becomes uneven, leading to disrupted fiber orientation and localized stress concentration, making fracture more likely in the later stages of cold drawing. Furthermore, the material's plastic reserve decreases, making it difficult to achieve the desired total deformation, resulting in a reduction in ultimate tensile strength. Furthermore, controlling the reheating temperature, deformation amount, and cold drawing rate can synergistically control deformation uniformity and ensure continuous fiber formation.

[0010] As a preferred solution, the high-tensile-strength XM-19 stainless steel has a tensile strength of 1100 MPa or greater and a grain size of grade 6 or greater. The XM-19 stainless steel obtained using the preparation method of the present invention has significantly improved tensile strength and a high grain size, while also achieving a post-fracture shrinkage of 53% or greater. Furthermore, using a further preferred preparation method, the tensile strength can reach over 1300 MPa, offering significant application advantages.

[0011] As a preferred solution, the stainless steel raw material used in the multi-forged XM-19 stainless steel forgings comprises the following composition by mass: 0.044% ≤ C ≤ 0.06%, Si ≤ 1.0%, Mn 4-6%, P ≤ 0.045%, S ≤ 0.03%, Cr 21.5-23.5%, Ni 11.8-13.5%, Mo 1.75-3.0%, N 0.2-0.4%, Nb 0.1-0.3%, V 0.1-0.3%, with the balance being Fe. The present invention increases the nickel content within the conventional XM-19 composition range to improve the toughness and impact resistance of the stainless steel; while appropriately increasing the molybdenum and chromium contents synergistically refines the grain size and enhances the toughness of the material.

[0012] As a preferred solution, the multi-forged XM-19 stainless steel forgings are obtained by melting the stainless steel raw material in an ESR furnace to control the oxide inclusion level to below 1.0, and then heating the billet and forging it multiple times. Experiments have found that the use of an ESR furnace (electroslag remelting) can significantly remove harmful impurity elements and non-metallic inclusion levels compared to conventional AOD furnace refining, reducing the increase in hydrogen and nitrogen in the molten steel and secondary oxidation. The steel ingot has a dense and uniform structure, a smooth surface, and uniform metallographic structure and chemical composition. More importantly, reducing the inclusion level to below 1.0 can reduce the brittleness of the material caused by coarse and angular inclusions during cold drawing. A small amount of inclusions can act as an effective barrier to dislocation movement, promoting the uniform accumulation of dislocation density, thereby synergistically improving the tensile strength of the stainless steel material. If the inclusion level is too high, the accumulation of inclusions will cause stress concentration, offsetting the strength improvement brought by work hardening, and even causing premature failure.

[0013] As a preferred solution, the conditions of the ESR furnace are: vacuum degree ≤ 10 -3 Pa, refining time ≥ 4h, electrode speed 5-10r / min, and a slag system of CaO-Al2O3-MgO. A sufficiently long refining time ensures that inclusions have ample time to float and be adsorbed by the slag layer, while a slow melting electrode speed maximizes the contact time between the slag and the stainless steel raw material. As a result, within the ESR furnace settings selected in this invention, the total amount of inclusions can be reduced by approximately 60%, with oxide inclusions reduced to a minimum of 0.5.

[0014] As a preferred solution, the conditions for heating the billet are: when the furnace temperature of the heating furnace is less than 150°C, the billet is loaded and the temperature of the heating furnace is raised to 330~370°C; after a heating time of ≥3h, the temperature of the heating furnace is raised to 630~670°C, and the heating rate is ≥80°C / h; after a heating time of ≥4h, the temperature of the heating furnace is raised to 880~920°C, and the heating rate is ≥80°C / h; after a heating time of ≥5h, the temperature of the heating furnace is raised to 1170~1190°C, and the heating rate is ≥150°C / h, and then the billet is taken out of the furnace for forging.

[0015] As a preferred solution, the multiple forgings include the first fire forging chamfering, the second fire forging upsetting chamfering, the third fire forging drawing chamfering, the fourth forging upsetting rounding, the fifth forging punching and re-melting, the sixth forging drawing and re-melting, and the seventh fire forging expanding and smoothing.

[0016] As a preferred solution, the initial forging temperature of each forging from the first fire forging to the seventh fire forging is above 1180°C, and the final forging temperature is above 800°C. The present invention adopts high-temperature initial forging and medium-low temperature final forging, which effectively suppresses the precipitation of harmful phases while ensuring the plastic deformation and microstructure control of the material. First, the higher initial forging temperature ensures that the stainless steel is in a high plasticity range of full austenitization in the initial stage of deformation, achieving large deformation without cracking; and when the forging temperature gradually drops from the peak value to the range above 800°C, although the material is still in the austenite stable zone, the driving force brought by the cooling is sufficient to stimulate dynamic recrystallization, and the grain size is gradually refined through multiple fire superposition forgings.

[0017] As a preferred solution, the first fire forging chamfering starts at above 1180℃, the surface of the ingot is lightly pressed by 30~60mm, the final forging temperature is ≥900℃, and the steel is returned to the furnace after pressing; the second fire forging upsetting chamfering is heated to above 1200℃, kept warm for more than 5h, the final forging temperature is ≥850℃, upsetting is performed to a forging ratio of ≥4, and the chamfering is smoothed; the third fire forging stretching chamfering starts at above 1200℃, kept warm for more than 5h, the final forging temperature is ≥850℃, the narrow anvil is stretched, and the single pass reduction is 20~50 mm, chamfered and returned to the furnace; the fourth forging, upsetting and rounding starts at above 1200℃, keeps warm for more than 5h, and then rounds; the fifth forging, punching and returning to the furnace starts at above 1200℃, keeps warm for more than 5h, and then returns to the furnace after punching; the sixth forging, drawing and returning to the furnace starts at above 1180℃, keeps warm for more than 3h, and the final forging temperature is ≥850℃, and then returns to the furnace after drawing; the seventh fire forging, hole expansion and flattening starts at above 1180℃, keeps warm for more than 3h, and the final forging temperature is ≥800℃, and the end face is flattened after hole expansion.

[0018] As a preferred solution, the cooling rate of the water quenching is ≥50°C / s. The present invention eliminates work hardening by rapid water quenching and fixes the grain size after solution heat treatment.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The present invention controls the temperature of the solution heat treatment and can use a high solution heat treatment temperature to dissolve the carbides and γ' phases in the matrix to obtain a uniform supersaturated solid solution, which is convenient for re-precipitating fine-grained and uniformly distributed carbides and γ' strengthening phases during water quenching. At the same time, the stress generated by hot and cold processing is eliminated, causing the alloy to recrystallize, and at the same time, it is convenient for further refining the austenite grain size in subsequent processes.

[0021] (2) The solution heat treatment and cold drawing process of the present invention have a significant synergistic effect. After solution treatment, the austenite grains are uniform. During cold drawing, the grains are elongated along the deformation direction to form a fibrous structure. Grain boundary strengthening and work hardening are superimposed, and the yield strength is significantly improved.

[0022] (3) The XM-19 stainless steel obtained by the method of the present invention has a grain size of 6 or above, a tensile strength of up to 1300 MPa or above, and a post-fracture shrinkage rate of up to 57%, which has obvious application advantages.

[0023] (4) The present invention adopts an ESR furnace refining process and a cold drawing process, which has obvious synergistic effects. The use of the ESR furnace can reduce the inclusion level to below level 1.0. During the cold drawing process, not only can the coarse and angular inclusions be reduced to reduce the brittleness of the material during the cold drawing process, but a small amount of inclusions can also serve as an effective obstacle to dislocation movement, promoting the uniform accumulation of dislocation density, thereby synergistically improving the tensile strength of the stainless steel material.

[0024] (5) The present invention can effectively avoid local excessive temperature and uneven fiber structure distribution by adopting the method of mid-way temperature recovery combined with single-pass post-annealing in the cold drawing process, which is conducive to improving the overall tensile strength of stainless steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a tensile strength performance diagram of the XM-19 super austenitic stainless steel prepared in Example 1 of the present invention.

[0026] Figure 2 This is a performance diagram of the post-fracture shrinkage of the XM-19 super austenitic stainless steel prepared in Example 1 of the present invention.

[0027] Figure 3 This is a metallographic diagram of the fibrous structure of the XM-19 super austenitic stainless steel prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0028] The present invention is further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments. Obviously, the embodiments described below are only a part of the embodiments, and all other embodiments obtained by professionals in this field without making creative efforts are still within the scope of protection of the present invention.

[0029] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0030] Example 1

[0031] A method for preparing XM-19 super austenitic stainless steel with high tensile strength is disclosed. The raw materials used have the following composition by mass fraction: C 0.044%, Si 0.75%, Mn 5.2%, P 0.022%, S 0.012%, Cr 21.8%, Ni 11.85%, Mo 1.85%, N 0.31%, Nb 0.25%, V 0.2%, and the balance is Fe; the nickel powder has a particle size of 20 to 80 mm.

[0032] Its preparation comprises the following steps:

[0033] S1 steel ingot preparation

[0034] The above raw materials are mixed and placed in an ESR furnace for smelting. The parameters of the ESR furnace are set as follows: vacuum degree ≤ 10 ^-3 Pa, refining time is 4h, electrode speed is 5r / min, slag system is CaO-Al2O3-MgO (mass ratio 4:3:2), and after smelting, cooling is performed to obtain steel ingots.

[0035] S2 sawing machine cutting

[0036] The blanks are sawn according to the target size, and the tolerance of the blanking size is controlled within ±3mm.

[0037] S3 Billet Heating

[0038] When the furnace temperature is less than 150℃, charge the materials. After heating time is greater than or equal to 2h, the furnace temperature is raised to 350℃±20℃; after heating time is greater than or equal to 3h, the furnace temperature is raised to 650℃±20℃, and the heating rate is not less than 80℃ / h; after heating time is greater than or equal to 4h, the furnace temperature is raised to 900℃±20℃, and the heating rate is not less than 80℃ / h; after heating time is greater than or equal to 5h, the furnace temperature is raised to 1180℃±10℃, and the heating rate is not less than 150℃ / h, and then the steel is taken out of the furnace for forging.

[0039] S4 First Fire Forging Chamfer

[0040] Forging starts at 1180℃, the surface of the ingot is lightly pressed 30mm, the final forging temperature is 900℃, and the ingot is returned to the furnace after pressing.

[0041] S5 second fire forging upsetting chamfer

[0042] Heat to the initial forging temperature of 1200℃, keep warm for 5h, and the final forging temperature is 850℃. Upset to a forging ratio of 4 and smooth the chamfers.

[0043] S6 third fire forging long chamfer

[0044] Forging started at 1200℃, kept warm for 5h, and the final forging temperature was 850℃. The narrow anvil was stretched, the single-pass reduction was 50mm, and the parts were chamfered and returned to the furnace.

[0045] S7 fourth fire forging upsetting and rounding

[0046] Start forging at 1200℃, keep warm for 5h, and final forging temperature is 850℃. After upsetting, roll into round shape.

[0047] S8 fifth fire forging punching remelting

[0048] The forging starts at 1200℃, keeps warm for 5 hours, and the final forging temperature is 850℃. After punching, it is returned to the furnace.

[0049] S9 Sixth Fire Forging Lengthened Back to the Refinement

[0050] The forging starts at 1180℃, keeps warm for 3h, and the final forging temperature is 850℃. After drawing, it is returned to the furnace.

[0051] S10 seventh fire forging hole expansion and flattening

[0052] The forging was started at 1180℃, kept warm for 3h, and the final forging temperature was 800℃. After the hole was expanded, the end surface was flattened to obtain the stainless steel forging.

[0053] S11: The stainless steel forgings are solution treated at a temperature of 1066℃, and the holding time is adjusted according to the cross-section (such as Φ50mm holding for 4h), and then water quenched at a cooling rate greater than 50℃ / s to eliminate work hardening.

[0054] S12: The forgings after water quenching are further subjected to multiple cold drawing hardening processes, wherein the cold drawing rate is 1 mm / s, the deformation of a single pass is controlled at 1.5%, and the total deformation is 15%. In a single pass, the temperature is returned to 80°C for 0.5 h after every 1 hour, and stress relief annealing at 200°C is performed after each pass.

[0055] Example 2

[0056] The difference between this embodiment and embodiment 1 is that the amount of Cr is changed to 21.7% and the amount of Mo is changed to 1.75% in terms of composition; the difference in preparation is that the temperature of the solution treatment in S11 is changed to 1060°C, the cold drawing rate in S12 is 2 mm / s, the deformation in a single pass is controlled at 2.5%, the total deformation is 15%, the temperature is returned to 60°C and kept warm for 1 hour every 2 hours in a single pass, and a stress relief annealing treatment at 200°C is performed after each pass, thereby obtaining XM-19 super austenitic stainless steel.

[0057] Example 3

[0058] The raw materials used in this embodiment have the following components by mass fraction: C 0.045%, Si 0.75%, Mn 5.2%, P 0.022%, S 0.012%, Cr 21.8%, Ni 11.85%, Mo 1.85%, N 0.31%, Nb 0.25%, V 0.2%, and the balance is Fe; the particle size of the nickel powder is 20-80 mm.

[0059] During the preparation process, the parameters of the S1 ESR furnace were set as follows: vacuum degree ≤ 10 ^-3 Pa, refining time is 5h, electrode speed is 10r / min, slag system is CaO-Al2O3-MgO (mass ratio 4:3:2), after smelting, cooling is performed to obtain steel ingot, S2~S11 are the same as in Example 1.

[0060] In S12, the forgings after water quenching are further subjected to multiple cold drawing hardening processes, wherein the cold drawing rate is 1.5 mm / s, the deformation of a single pass is controlled at 2%, and the total deformation is 12%. In a single pass, the temperature is returned to 80°C for 1 hour after every 1 hour, and a stress relief annealing treatment at 200°C is performed after each pass.

[0061] Comparative Example 1

[0062] The only difference between this comparative example and Example 1 is that the temperature of the solution treatment is changed to 1055° C., and the other conditions and steps are the same, thereby obtaining XM-19 super austenitic stainless steel.

[0063] Comparative Example 2

[0064] The only difference between this comparative example and Example 2 is that the temperature of the solution treatment is changed to 1055° C., and the other conditions and steps are the same, thereby obtaining XM-19 super austenitic stainless steel.

[0065] Comparative Example 3

[0066] The only difference between this comparative example and Example 1 is that the ESR furnace is replaced by an AOD furnace, and the remaining steps and conditions are the same to obtain XM-19 super austenitic stainless steel.

[0067] Comparative Example 4

[0068] The only difference between this comparative example and Example 3 is that during the cold drawing process, only a 200°C stress relief annealing treatment is performed after each pass, and a single pass with an interval of warming is not used. The other steps and conditions are the same. The forging broke in the later stage of the cold drawing process.

[0069] Comparative Example 5

[0070] The only difference between this comparative example and Example 3 is that the cold drawing rate is changed to 4 mm / s during the cold drawing process, and the temperature of the intermediate interval of the single pass is changed to 100° C. The other steps and conditions are the same, and XM-19 super austenitic stainless steel is obtained.

[0071] The performance comparison of the XM-19 super austenitic stainless steel prepared in Examples 1 to 3 and Comparative Examples 1 to 2 and Comparative Example 5 is shown in Table 1.

[0072]

[0073] The performance comparison of the XM-19 super austenitic stainless steel prepared in Example 1 and Comparative Example 3 is shown in Table 2.

[0074]

Claims

1. A method for preparing XM-19 super austenitic stainless steel with high tensile strength, characterized by: The XM-19 stainless steel forgings which have been forged multiple times are subjected to solution heat treatment at a temperature of 1060-1066°C to form uniform austenite grains, and then subjected to water quenching to eliminate work hardening and multiple cold drawing to form fibrous structure. The conditions for the multi-pass cold drawing work hardening are: the deformation of a single pass is controlled at 1.5-2.5%, the cold drawing rate is 1-2 mm / s, the total deformation is 10-15%, the temperature is returned to 60-80° C. and kept warm for 0.5-1 hour every 1-2 hours in a single pass, and a stress relief annealing treatment at 200-220° C. is performed after each pass.

2. The method for preparing XM-19 super austenitic stainless steel with high tensile strength according to claim 1, characterized in that: The high-tensile-strength XM-19 stainless steel has a tensile strength of 1100 MPa or more and a grain size of grade 6 or more.

3. The method for preparing XM-19 super austenitic stainless steel with high tensile strength according to claim 1 or 2, characterized in that: The stainless steel raw material used in the multi-forged XM-19 stainless steel forgings is composed of the following mass fractions: 0.044%≤C≤0.06%, Si≤1.0%, Mn 4-6%, P≤0.045%, S≤0.03%, Cr 21.5-23.5%, Ni 11.8-13.5%, Mo 1.75-3.0%, N 0.2-0.4%, Nb 0.1-0.3%, V 0.1-0.3%, and the balance is Fe.

4. The method for preparing XM-19 super austenitic stainless steel with high tensile strength according to claim 3, characterized in that: The multi-forged XM-19 stainless steel forgings are obtained by melting the stainless steel raw material in an ESR furnace, controlling the oxide inclusion level to be below level 1.0, and then heating the blank and forging it multiple times.

5. The method for preparing XM-19 super austenitic stainless steel with high tensile strength according to claim 4, characterized in that: The conditions of the ESR furnace are: vacuum degree ≤ 10 -3 Pa, refining time ≥4h, electrode speed 5~10r / min, and slag system CaO-Al2O3-MgO.

6. The method for preparing XM-19 super austenitic stainless steel with high tensile strength according to claim 4, characterized in that: The conditions for heating the billet are as follows: when the furnace temperature of the heating furnace is less than 150°C, the billet is loaded and the temperature of the heating furnace is raised to 330-370°C; after a heating time of ≥3h, the temperature of the heating furnace is raised to 630-670°C, and the heating rate is ≥80°C / h; after a heating time of ≥4h, the temperature of the heating furnace is raised to 880-920°C, and the heating rate is ≥80°C / h; after a heating time of ≥5h, the temperature of the heating furnace is raised to 1170-1190°C, and the heating rate is ≥150°C / h, and then the billet is taken out of the furnace for forging.

7. The method for preparing XM-19 super austenitic stainless steel with high tensile strength according to claim 4, characterized in that: The multiple forgings include the first fire forging chamfering, the second fire forging upsetting chamfering, the third fire forging drawing and chamfering, the fourth forging upsetting and rounding, the fifth forging punching and re-melting, the sixth forging drawing and re-melting, and the seventh fire forging expanding and leveling.

8. The method for preparing XM-19 super austenitic stainless steel with high tensile strength according to claim 6, characterized in that: The initial forging temperature of each forging from the first to the seventh fire forging is above 1180°C, and the final forging temperature is above 800°C.

9. The method for preparing XM-19 super austenitic stainless steel with high tensile strength according to claim 1 or 8, characterized in that: The cooling rate of the water quenching is ≥50°C / s.

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