A high-strength maraging stainless steel with warm deformation and aging process and its preparation method

Abstract

The present invention discloses a high-strength martensitic aging stainless steel subjected to a warm deformation and aging process and a preparation method thereof, which belongs to the field of martensitic stainless steel. The preparation method comprises the following steps: (1) smelting the high-strength martensitic aging stainless steel subjected to a warm deformation and aging process by vacuum melting and vacuum degassing, and casting the steel ingot after the designed component ratio is met; (2) homogenizing and hot rolling the steel ingot to obtain a steel plate; (3) performing a solid solution treatment on the steel plate; (4) performing a warm deformation and aging treatment after the solid solution treatment; the high-strength martensitic aging stainless steel obtained after the warm deformation and aging treatment has a dislocation density of ≥3.5×10 15 m ‑2 The present invention precisely controls the precipitation-strengthening nanophase, and the nanoscale precipitated phase is fine and dispersed, showing a uniform distribution in the matrix, with excellent mechanical properties, a tensile strength of 2188MPa, a yield strength of 1904MPa, and a hardness of 608HV.

Description

Technical Field

[0001] The present invention belongs to the field of martensitic stainless steel, and in particular relates to a high-strength martensitic aging stainless steel with a warm deformation and aging process and a preparation method thereof. Background Art

[0002] Maraging stainless steel is widely used in aerospace, marine engineering, pressure vessels and precision manufacturing due to its excellent strength, toughness and corrosion resistance. Its traditional aging treatment process usually includes solution treatment, quenching and aging treatment to promote the precipitation of precipitate phase, thereby strengthening the matrix. The strengthening mechanism of maraging stainless steel mainly relies on the precipitation of dispersed intermetallic compounds such as Cu, NiAl, Ni3Ti, etc. in the matrix during the aging process to improve its comprehensive mechanical properties through precipitation strengthening and dislocation strengthening. However, the traditional aging process has significant limitations. First, the nucleation density of the precipitate phase in the conventional aging process is low, and it mainly relies on defects such as matrix vacancies and grain boundaries as nucleation sites, resulting in uneven distribution of the precipitate phase and insufficient density (usually <10 22 / m 3 Secondly, the precipitation phase has a significant tendency to coarsen, making Ostwald ripening more likely to occur during aging, leading to a strength-toughness mismatch. Furthermore, the precipitation kinetics of traditional aging processes are slow, requiring long aging times (4-8 hours) to reach peak strength, limiting production efficiency.

[0003] Applying warm deformation aging can effectively break through the above bottlenecks by coupling plastic deformation and aging processes. Its core advantages are reflected in three levels: At the thermodynamic level, the dislocation network and deformation bands generated by warm deformation provide high-density nucleation sites, significantly reducing the nucleation energy barrier of the precipitate phase. At the kinetic level, the deformation-induced dislocation conduits accelerate the short-range diffusion of solute atoms, reducing the precipitation activation energy by about 15%-30%, allowing the precipitate phase to quickly reach the critical nucleation size. At the organizational regulation level, the dynamic strain aging effect inhibits the coarsening of the precipitate phase, achieves refinement of the precipitate phase size by pinning dislocations, and improves the spatial distribution uniformity of the precipitate phase.

[0004] Chinese patent CN115627326A discloses a method for eliminating delta-ferrite in maraging steel. This method produces maraging steel with eliminated delta-ferrite by subjecting fully austenitic steel to a hot-rolling-warm-rolling-pickling-aging process. However, the presence of a small amount of ferrite in the steel negatively impacts mechanical properties. Furthermore, the warm rolling process occurs during the solutionization phase, resulting in dislocations that are not available for nucleation of precipitates during the aging process. Chinese patent CN114032472A discloses a novel cobalt-free maraging steel and its strengthening and toughening process. This patent optimizes the grain size and microstructure through two solutionization treatments combined with three mutually perpendicular deformation treatments, resulting in dispersed nanoscale precipitates during the aging process. However, the process employed in this patent is relatively complex, hindering its widespread application in practical production. Summary of the Invention

[0005] To address the problem of reduced number and density of precipitated phases due to decreased dislocation density during the aging process of existing maraging stainless steel, the present invention aims to provide a high-strength maraging stainless steel with a warm deformation and aging process and a preparation method thereof. By combining warm deformation with the aging process, precise control of the precipitation-strengthening nanophase is achieved. Through appropriate plastic deformation, the maraging stainless steel forms a higher density dislocation structure during the aging process, thereby providing a large number of nucleation sites, promoting the dispersed precipitation of precipitated phases, avoiding dislocation annihilation during the aging process, and enabling the precipitation-strengthening phase to be more evenly distributed in the martensite matrix.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] The present invention provides a method for preparing high-strength maraging stainless steel by a warm deformation and aging process, comprising the following steps:

[0008] (1) According to the designed component ratio of high-strength maraging stainless steel of warm deformation and aging process, the steel is smelted through vacuum melting and vacuum degassing treatment, and the steel ingot is cast after the designed component requirements are met;

[0009] (2) homogenizing and hot rolling the steel ingot to obtain steel plates;

[0010] (3) Solution treatment of the steel plate;

[0011] (4) After solution treatment, warm deformation and aging treatment are performed. The steel plate after solution treatment is heated in a vacuum, inert protective atmosphere or air, and aging treatment is performed. Warm deformation is performed in the middle of the aging treatment. The dislocation annihilation during the aging process is slowed down. After aging treatment, the steel plate is cooled to room temperature. Since the precipitation process is induced by deformation, the number density and volume fraction of the precipitated phase are effectively controlled. The nanoscale precipitated phase is not only fine and dispersed, but also presents a more optimized distribution state in the matrix.

[0012] The dislocation density of high strength maraging stainless steel obtained after warm deformation and aging treatment is ≥3.5×10 15 m -2 .

[0013] Furthermore, the designed composition of the high-strength maraging stainless steel subjected to the medium-temperature deformation and aging process in step (1) comprises, by mass percentage, Ni: 8.0%-12.0%, Cr: 12.0%-18.0%, Al: 0.5%-2.5%, Ti: 0.5%-2.5%, Mo: 1.5%-3.5%, Cu: 0.5%-2.5%, Mn: 0.5%-1.5%, Si: 0.3%-1.5%, C≤0.005%, P≤0.003%, S≤0.003%, O≤0.003%, and the balance is Fe.

[0014] Furthermore, in step (2), the steel ingot is heated in a vacuum, inert protective atmosphere or in air, with a homogenization treatment temperature of 950°C-1250°C and a holding time of 1h-8h, and then taken out of the furnace for hot rolling, with an initial rolling temperature of 900°C-1100°C, a final rolling temperature ≥850°C, a total reduction amount of 30%-90%, and cooled to room temperature after hot rolling.

[0015] Furthermore, in step (3), the steel plate is heated in a vacuum, inert protective atmosphere or air in a furnace, the solution treatment temperature is 850°C-1150°C, the holding time is 1h-6h, and the steel plate is cooled to room temperature after the solution treatment.

[0016] Furthermore, in step (4), the aging treatment temperature is 400°C-650°C, the holding time before warm deformation is 0.5h-4h, and the holding time after warm deformation is 0.5h-6h.

[0017] Furthermore, the total deformation amount of the warm deformation in step (4) is 10%-60%, and the deformation is performed in 1-10 passes.

[0018] Furthermore, the cooling method in step (2) and step (4) is air cooling or oil cooling, and the cooling method in step (3) is oil cooling or water cooling to room temperature.

[0019] The present invention provides a high-strength maraging stainless steel subjected to a warm deformation and aging process. By adopting the method for preparing the high-strength maraging stainless steel subjected to a warm deformation and aging process, a precipitation strengthening phase is uniformly distributed in a martensite matrix.

[0020] Furthermore, the high-strength maraging stainless steel subjected to the warm deformation and aging process has a tensile strength of 1825MPa-2188MPa, a yield strength of 1608MPa-1904MPa, and a hardness of 540HV-608HV; when the tensile strength is between 2108MPa-2188MPa, the total elongation is 3%-8.8%, and the dislocation density is 5.5×10 15 m -2 -8.7×10 15 m -2 When the tensile strength is between 1825MPa and 2108MPa, the total elongation is between 8.8% and 13.3%, and the dislocation density is 3.5×10 15 m -2 -5.5×10 15 m -2 .

[0021] Advantages and effects of the present invention:

[0022] The preparation process of the high-strength maraging stainless steel by the warm deformation aging process of the present invention is simple, has low production cost, and is easy to realize industrial production. The precipitation strengthening nanophase is precisely controlled, the nanoscale precipitate phase is finely dispersed, and is uniformly distributed in the matrix, thereby obtaining a high-strength maraging stainless steel with excellent mechanical properties, with a tensile strength of ≥1825MPa, a yield strength of ≥1608MPa, a hardness of ≥540HV, a total elongation of ≥3.0%, and a dislocation density of ≥3.5×10 15 m -2 . BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the heat treatment process roadmap of Example 1;

[0024] Figure 2 These are mechanical property diagrams of Example 1 under the warm deformation aging process and Comparative Example 1 under the traditional aging process. DETAILED DESCRIPTION

[0025] The present invention is described in detail below with reference to the embodiments.

[0026] Example 1

[0027] The present invention provides a method for preparing high-strength maraging stainless steel by a warm deformation and aging process, wherein the heat treatment process route is as follows: Figure 1 As shown, the following steps are included:

[0028] (1) According to the following mass percentages: Ni: 8.0%, Cr: 12.0%, Al: 2.5%, Ti: 2.5%, Mo: 3.5%, Cu: 0.5%, Mn: 0.7%, Si: 1.5%, C≤0.005%, P≤0.003%, S≤0.003%, and the balance is Fe, metal Fe, metal Cr, metal Ni, metal Ti, metal Mn, metal Mo, metal Cu, metal Al and silicon with a purity greater than 99.5% are selected as raw materials, smelted in a vacuum induction melting furnace, and cast to obtain steel ingots after meeting the design composition requirements;

[0029] (2) The steel ingot is homogenized and hot rolled. The steel ingot is heated in a nitrogen atmosphere. The homogenization treatment is carried out by keeping the temperature at 1100°C for 8 hours. Then the steel ingot is taken out of the furnace and hot rolled. The initial rolling temperature is 1100°C, the final rolling temperature is ≥940°C, and the total reduction is 90%. The steel plate is obtained and then cooled to room temperature by air cooling.

[0030] (3) The steel plate is subjected to solution treatment. The steel plate is heated in a vacuum furnace. The solution treatment is carried out at 1050 ° C for 2.5 hours and then cooled to room temperature by oil cooling.

[0031] (4) Warm deformation and aging treatment: The steel plate after solution treatment is heated in a vacuum furnace for aging treatment. The aging treatment temperature is 500℃ and the holding time is 4h. Then, it is warm deformed at 500℃ with a total deformation of 60%. The deformation is carried out in 10 passes, and then it is kept at this temperature for 2h. Then, it is cooled to room temperature by oil cooling to obtain high-strength martensitic aging stainless steel by warm deformation and aging process.

[0032] like Figure 2 As shown, the high-strength maraging stainless steel prepared by the warm deformation aging process in Example 1 was subjected to mechanical property tests, and the yield strength was 1850 MPa, the tensile strength was 2186 MPa, and the elongation was 3.0%. The hardness of the alloy was tested by an HVS-1000SPTA Vickers hardness tester with a load of 500 g for 15 seconds. The average hardness of the ten hardness tests was 586 HV, which was 9.7% higher than that of the high-strength maraging stainless steel prepared by conventional aging in Comparative Example 1. The dislocation density reached 7.7×10 15 m -2 .

[0033] Example 2

[0034] The present invention provides a method for preparing high-strength maraging stainless steel by a warm deformation and aging process, comprising the following steps:

[0035] (1) According to the following mass percentages: Ni: 12.0%, Cr: 18.0%, Al: 2.0%, Ti: 2.0%, Mo: 1.5%, Cu: 2.5%, Mn: 0.5%, Si: 0.5%, C≤0.005%, P≤0.003%, S≤0.003%, and the balance is Fe, metal Fe, metal Cr, metal Ni, metal Ti, metal Mn, metal Mo, metal Cu, metal Al and silicon with a purity greater than 99.5% are selected as raw materials, smelted in a vacuum induction melting furnace, and cast to obtain steel ingots after meeting the design composition requirements;

[0036] (2) The steel ingot is homogenized and hot rolled. The steel ingot is heated in a vacuum furnace. The homogenization treatment is carried out by keeping the temperature at 1250℃ for 1 hour. Then the ingot is taken out of the furnace and hot rolled. The initial rolling temperature is 900℃, the final rolling temperature is ≥850℃, and the total reduction is 30%. The steel plate is obtained and then cooled to room temperature by oil cooling.

[0037] (3) The steel plate is subjected to solution treatment. The steel plate is heated in a furnace in nitrogen. The solution treatment is carried out at 1150 ° C for 1 hour and then cooled to room temperature by water cooling.

[0038] (4) Warm deformation and aging treatment: The steel plate after solution treatment is heated in argon gas and aged at 650 °C for 0.5 h. Then, it is deformed at 650 °C with a total deformation of 10%. The deformation is carried out in 6 passes, and then kept at this temperature for 4 h. Then, it is cooled to room temperature by air cooling.

[0039] The high-strength maraging stainless steel prepared by the warm deformation and aging process in Example 2 was subjected to mechanical property tests, and the yield strength was 1804 MPa, the tensile strength was 2108 MPa, and the elongation was 8.8%. The hardness of the alloy was tested by an HVS-1000 SPTA Vickers hardness tester with a load of 500 g for 15 s. The average hardness of the ten hardness tests was 580 HV. The dislocation density reached 5.5×10 15 m -2 .

[0040] Example 3

[0041] The present invention provides a method for preparing high-strength maraging stainless steel by a warm deformation and aging process, comprising the following steps:

[0042] (1) According to the following mass percentages: Ni: 10.0%, Cr: 14.0%, Al: 0.5%, Ti: 0.5%, Mo: 2.0%, Cu: 2.0%, Mn: 1.0%, Si: 1.0%, C≤0.005%, P≤0.003%, S≤0.003%, and the balance is Fe, metal Fe, metal Cr, metal Ni, metal Ti, metal Mn, metal Mo, metal Cu, metal Al and silicon with a purity greater than 99.5% are selected as raw materials, smelted in a vacuum induction melting furnace, and cast to obtain steel ingots after meeting the design composition requirements;

[0043] (2) The steel ingot is homogenized and hot rolled. The steel ingot is heated in a vacuum furnace. The homogenization treatment is carried out by keeping the temperature at 950℃ for 2h. Then the ingot is taken out of the furnace and hot rolled. The initial rolling temperature is 900℃, the final rolling temperature is ≥850℃, and the total reduction is 90%. The steel plate is obtained and then cooled to room temperature by oil cooling.

[0044] (3) The steel plate is subjected to solution treatment. The steel plate is heated in a vacuum furnace. The solution treatment is carried out at 850 ° C for 6 hours and then cooled to room temperature by water cooling.

[0045] (4) Warm deformation and aging treatment: The steel plate after solution treatment is heated in the air with the furnace for aging treatment. The aging temperature is 400℃ and the holding time is 4h. Then, it is warm deformed at 400℃ with a total deformation of 60%. The deformation is carried out in 2 passes, and then it is kept warm for 6h. Then, it is cooled to room temperature by air cooling.

[0046] The high-strength maraging stainless steel prepared by the warm deformation and aging process in Example 3 was subjected to mechanical property tests, and the yield strength was 1854 MPa, the tensile strength was 2188 MPa, and the elongation was 5.8%. The hardness of the alloy was tested by an HVS-1000 SPTA Vickers hardness tester with a load of 500 g for 15 s. The average hardness of the ten hardness tests was 600 HV. The dislocation density reached 8.7×10 15 m -2 .

[0047] Example 4

[0048] The present invention provides a method for preparing high-strength maraging stainless steel by a warm deformation and aging process, comprising the following steps:

[0049] (1) According to the following mass percentages: Ni: 12.0%, Cr: 14.0%, Al: 1.0%, Ti: 1.0%, Mo: 2.0%, Cu: 2.0%, Mn: 1.5%, Si: 1.5%, C≤0.005%, P≤0.003%, S≤0.003%, and the balance is Fe, metal Fe, metal Cr, metal Ni, metal Ti, metal Mn, metal Mo, metal Cu, metal Al and silicon with a purity greater than 99.5% are selected as raw materials, smelted in a vacuum induction melting furnace, and cast to obtain steel ingots after meeting the design composition requirements;

[0050] (2) The steel ingot is homogenized and hot rolled. The steel ingot is heated in the air with the furnace. The homogenization treatment is to keep the temperature at 1100℃ for 2h, then the steel ingot is taken out of the furnace for hot rolling. The initial rolling temperature is 1050℃, the final rolling temperature is ≥950℃, and the total reduction is 50% to obtain the steel plate. The steel plate is then cooled to room temperature by air cooling.

[0051] (3) The steel plate is subjected to solution treatment. The steel plate is heated in the air with the furnace. The solution treatment is carried out at 1100 ° C for 2 hours and then cooled to room temperature by water cooling.

[0052] (4) Warm deformation and aging treatment: The steel plate after solution treatment is heated in a vacuum furnace for aging treatment. The aging temperature is 500℃ and the holding time is 2h. Then, it is warm deformed at 500℃ with a total deformation of 20%. The deformation is carried out in one pass, and then it is kept warm for 0.5h. Then, it is cooled to room temperature by air cooling.

[0053] The high-strength maraging stainless steel prepared by the warm deformation and aging process in Example 4 was subjected to mechanical property tests. The yield strength was 1904 MPa, the tensile strength was 2118 MPa, and the elongation was 5.1%. The hardness of the alloy was tested by an HVS-1000 SPTA Vickers hardness tester with a load of 500 g for 15 s. The average hardness of the ten hardness tests was 608 HV. The dislocation density reached 5.7×10 15 m -2 .

[0054] Example 5

[0055] The present invention provides a method for preparing high-strength maraging stainless steel by a warm deformation and aging process, comprising the following steps:

[0056] (1) According to the following mass percentages: Ni: 12.0%, Cr: 12.0%, Al: 2.5%, Ti: 2.5%, Mo: 3.5%, Cu: 2.5%, Mn: 1.5%, Si: 0.3%, C≤0.005%, P≤0.003%, S≤0.003%, and the balance is Fe, metal Fe, metal Cr, metal Ni, metal Ti, metal Mn, metal Mo, metal Cu, metal Al and silicon with a purity greater than 99.5% are selected as raw materials, smelted in a vacuum induction melting furnace, and cast to obtain steel ingots after meeting the design composition requirements;

[0057] (2) The steel ingot is homogenized and hot rolled. The steel ingot is heated in a nitrogen atmosphere. The homogenization treatment is carried out by keeping the temperature at 1200℃ for 8 hours. Then the steel ingot is taken out of the furnace and hot rolled. The initial rolling temperature is 1100℃, the final rolling temperature is ≥900℃, and the total reduction is 30%. The steel plate is obtained and then cooled to room temperature by air cooling.

[0058] (3) The steel plate is subjected to solution treatment. The steel plate is heated in a vacuum furnace. The solution treatment is carried out at 1050 ° C for 2.5 hours and then cooled to room temperature by oil cooling.

[0059] (4) Warm deformation and aging treatment: The steel plate after solution treatment is heated in a vacuum furnace for aging treatment. The aging treatment temperature is 600℃ and the holding time is 4h. Then, it is warm deformed at 600℃ with a total deformation of 20%. The deformation is carried out in 2 passes and then kept at this temperature for 4h. Then, it is cooled to room temperature by oil cooling to obtain high-strength martensitic aging stainless steel by warm deformation and aging process.

[0060] The high-strength maraging stainless steel prepared by the warm deformation aging process in Example 5 was subjected to mechanical property testing, and the yield strength was 1678 MPa, the tensile strength was 1877 MPa, and the elongation was 10.8%. The hardness of the alloy was tested using an HVS-1000 SPTA Vickers hardness tester. The hardness test results were averaged over ten tests with a load of 500 g for 15 seconds, and the hardness was 546 HV. Compared with the high-strength maraging stainless steel prepared by conventional aging in Comparative Example 1, the hardness was increased by 2.25%. The dislocation density reached 3.7×10 15 m -2 .

[0061] Example 6

[0062] The present invention provides a method for preparing high-strength maraging stainless steel by a warm deformation and aging process, comprising the following steps:

[0063] (1) According to the following mass percentages: Ni: 8.0%, Cr: 18.0%, Al: 2.5%, Ti: 0.5%, Mo: 3.5%, Cu: 2.5%, Mn: 1.5%, Si: 0.3%, C≤0.005%, P≤0.003%, S≤0.003%, and the balance is Fe, metal Fe, metal Cr, metal Ni, metal Ti, metal Mn, metal Mo, metal Cu, metal Al and silicon with a purity greater than 99.5% are selected as raw materials, smelted in a vacuum induction melting furnace, and cast to obtain steel ingots after meeting the design composition requirements;

[0064] (2) The steel ingot is homogenized and hot rolled. The steel ingot is heated in a nitrogen atmosphere. The homogenization treatment is carried out by keeping the temperature at 1200℃ for 8 hours. Then the steel ingot is taken out of the furnace and hot rolled. The initial rolling temperature is 1100℃, the final rolling temperature is ≥900℃, and the total reduction is 30%. The steel plate is obtained and then cooled to room temperature by air cooling.

[0065] (3) The steel plate is subjected to solution treatment. The steel plate is heated in a vacuum furnace. The solution treatment is carried out at 1050 ° C for 2.5 hours and then cooled to room temperature by oil cooling.

[0066] (4) Warm deformation and aging treatment: The steel plate after solution treatment is heated in a vacuum furnace for aging treatment. The aging treatment temperature is 600℃ and the holding time is 4h. Then, it is warm deformed at 600℃ with a total deformation of 20%. The deformation is carried out in 2 passes and then kept at this temperature for 6h. Then, it is cooled to room temperature by oil cooling to obtain high-strength martensitic aging stainless steel by warm deformation and aging process.

[0067] The high-strength maraging stainless steel prepared by the warm deformation aging process in Example 6 was subjected to mechanical property testing, and the yield strength, tensile strength, and elongation were 1608 MPa, 1825 MPa, and 13.3%. The hardness of the alloy was tested using an HVS-1000 SPTA Vickers hardness tester. The hardness test results were averaged over ten tests with a load of 500 g for 15 seconds, and the hardness was 540 HV. Compared with the high-strength maraging stainless steel prepared by conventional aging in Comparative Example 1, the hardness was increased by 1.12%. The dislocation density reached 3.5×10 15 m -2 .

[0068] The present invention increases the dislocation density of martensite during the aging process through warm deformation, thereby regulating the number density of nano-precipitates in the martensite matrix, and successfully obtains stainless steel with excellent performance and a tensile strength of up to 2.1GPa, which can be used in key structures such as ships, marine engineering, and aerospace engineering.

[0069] Comparative Example 1

[0070] A method for preparing high-strength maraging stainless steel using a conventional aging process, which differs from Example 1 in that a conventional aging treatment is used instead of a warm deformation aging treatment, comprises the following steps:

[0071] (1) According to the following mass percentages: Ni: 8.0%, Cr: 12.0%, Al: 2.5%, Ti: 2.5%, Mo: 3.5%, Cu: 0.5%, Mn: 0.7%, Si: 1.5%, C≤0.005%, P≤0.003%, S≤0.003%, and the balance is Fe, metal Fe, metal Cr, metal Ni, metal Ti, metal Mn, metal Mo, metal Cu, metal Al and silicon with a purity greater than 99.5% are selected as raw materials, smelted in a vacuum induction melting furnace, and cast to obtain steel ingots after meeting the design composition requirements;

[0072] (2) The steel ingot is homogenized and hot rolled. The steel ingot is heated in a nitrogen atmosphere. The homogenization treatment is carried out by keeping the temperature at 1100°C for 8 hours. Then the steel ingot is taken out of the furnace and hot rolled. The initial rolling temperature is 1100°C, the final rolling temperature is ≥940°C, and the total reduction is 90%. The steel plate is obtained and then cooled to room temperature by air cooling.

[0073] (3) The steel plate is subjected to solution treatment. The steel plate is heated in a vacuum furnace. The solution treatment is carried out at 1050 ° C for 2.5 hours and then cooled to room temperature by oil cooling.

[0074] (4) Conventional aging treatment: The steel plate after solution treatment is heated in a vacuum furnace for aging treatment. The aging treatment temperature is 500 °C and the holding time is 6 h. Then, it is cooled to room temperature by oil cooling to obtain high-strength martensitic aging stainless steel by conventional aging process.

[0075] like Figure 2 As shown, the high-strength martensitic aging stainless steel prepared in this comparative example 1 was subjected to mechanical property tests, and the yield strength was 1589 MPa, the tensile strength was 1728 MPa, and the elongation was 4.5%. The hardness of the alloy was tested by an HVS-1000 SPTA Vickers hardness tester with a load of 500 g for 15 s. The hardness test results were averaged ten times, and the hardness was 534 HV; the dislocation density was 2.3×10 15 m -2 .

Claims

1. A method for preparing high-strength maraging stainless steel by warm deformation and aging process, characterized in that: The following steps are involved: (1) According to the design component ratio of high-strength martensitic aging stainless steel by warm deformation aging process, in terms of mass percentage, it includes Ni: 8.0%-12.0%, Cr: 12.0%-18.0%, Al: 0.5%-2.5%, Ti: 0.5%-2.5%, Mo: 1.5%-3.5%, Cu: 0.5%-2.5%, Mn: 0.5%-1.5%, Si: 0.3%-1.5%, C≤0.005%, P≤0.003%, S≤0.003%, O≤0.003%, and the balance is Fe. It is smelted by vacuum melting and vacuum degassing treatment, and after meeting the design component requirements, it is cast to obtain a steel ingot; (2) homogenizing and hot rolling the steel ingot to obtain steel plates; (3) Solution treatment of the steel plate; (4) After solution treatment, warm deformation and aging treatment are performed. The steel plate after solution treatment is heated in a vacuum, inert protective atmosphere or air with the furnace for aging treatment, and warm deformation is performed in the middle of the aging treatment. The aging treatment temperature is 400℃-650℃, the holding time before warm deformation is 0.5h-4h, and the holding time after warm deformation is 0.5h-6h. The dislocation annihilation during the aging process is slowed down, and the steel plate is cooled to room temperature after aging treatment. The dislocation density of high strength maraging stainless steel obtained after warm deformation and aging treatment is ≥3.5×10 15 m -2 .

2. The method for preparing high-strength maraging stainless steel by warm deformation and aging process according to claim 1, characterized in that: Step (2) The steel ingot is heated in a vacuum, inert protective atmosphere or air with a furnace, the homogenization treatment temperature is 950°C-1250°C, the holding time is 1h-8h, and then it is taken out of the furnace and hot rolled, the initial rolling temperature is 900°C-1100°C, the final rolling temperature is ≥850°C, the total reduction amount is 30%-90%, and it is cooled to room temperature after hot rolling.

3. The method for preparing high-strength maraging stainless steel by warm deformation and aging process according to claim 1, characterized in that: Step (3) The steel plate is heated in a furnace in a vacuum, inert protective atmosphere or air, the solution treatment temperature is 850°C-1150°C, the holding time is 1h-6h, and the steel plate is cooled to room temperature after the solution treatment.

4. The method for preparing high-strength maraging stainless steel by warm deformation and aging process according to claim 1, characterized in that: The total deformation amount of warm deformation in step (4) is 10%-60%, and the deformation is carried out in 1-10 steps.

5. The method for preparing high-strength maraging stainless steel by warm deformation and aging process according to claim 1, characterized in that: The cooling method in step (2) and step (4) is air cooling or oil cooling, and the cooling method in step (3) is oil cooling or water cooling to room temperature.

6. A high-strength maraging stainless steel processed by warm deformation and aging process, characterized in that: The high-strength maraging stainless steel is prepared by the preparation method of the warm deformation and aging process according to any one of claims 1 to 5, and the precipitation strengthening phase is uniformly distributed in the martensitic matrix.

7. The high-strength maraging stainless steel subjected to warm deformation and aging process according to claim 6, characterized in that: The high-strength maraging stainless steel subjected to the warm deformation and aging process has a tensile strength of 1825MPa-2188MPa, a yield strength of 1608MPa-1904MPa, and a hardness of 540HV-608HV. When the tensile strength is between 2108MPa-2188MPa, the total elongation is 3%-8.8%, and the dislocation density is 5.5×10 15 m -2 -8.7×10 15 m -2 When the tensile strength is between 1825MPa and 2108MPa, the total elongation is between 8.8% and 13.3%, and the dislocation density is 3.5×10 15 m -2 -5.5×10 15 m -2 .

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