Preparation method of nano-pore reinforced high-strength plastic low-density stainless steel

Abstract

The present application belongs to the technical field of metal material preparation, and particularly relates to a preparation method of nano-pore reinforced high-strength and high-plasticity low-density stainless steel, characterized in that the method comprises primary rolling, annealing, secondary rolling and tempering. The present application has the following beneficial effects: 1) nano-pores are innovatively introduced into the stainless steel sintered felt, the strength of the steel is successfully improved by using the interface strengthening of the nano-pores, the volume loss caused by the pores reduces the density of the steel, the specific strength of the steel is further improved, the excellent deformation capacity of the pores enables the steel to maintain excellent ductility, and the strength is increased and the density is reduced; 2) the nano-pore reinforced stainless steel of the present application has the strength increased by 2.5 times and the specific strength increased by 2.78 times compared with the traditional dense stainless steel without losing plasticity, the strength and plasticity of the stainless steel are reinforced, far exceeding the existing stainless steel material, and more importantly, the nano-pore reinforcement mechanism of the present application provides a new idea for the strength and plasticity design of steel materials.

Description

Technical Field

[0001] This invention belongs to the field of metal material preparation technology, and particularly relates to a method for preparing nanoporous reinforced high-strength, ductile, low-density stainless steel. Background Technology

[0002] Lightweighting is a perennial theme in the aerospace field, playing a significant role in driving the aerospace economy and promoting its marketization. Due to its excellent corrosion resistance and high-temperature mechanical properties, stainless steel is widely used in deep space probes, rockets, aircraft, and other aerospace applications. Currently, the best way to reduce the weight of stainless steel is through methods such as grain refinement and precipitation strengthening to increase the steel's specific strength. For example:

[0003] Patent document CN 113088652 A discloses a method for preparing a dispersion-strengthened, highly stable medical high-nitrogen nickel-free austenitic stainless steel. By adjusting a heat treatment process for high-nitrogen austenitic stainless steel, the number of nano-precipitates in the steel is significantly increased, resulting in a 45% increase in the specific hardness of the steel.

[0004] Patent document CN118291870A discloses a corrosion-resistant austenitic stainless steel material and its preparation method based on Sigma phase dispersion strengthening. By increasing the content of Cr and Al elements in a stainless steel and controlling the heat treatment process, a large amount of submicron-sized Sigma is precipitated in the steel, and the specific strength of the steel is increased by 1.2 times.

[0005] Based on the existing technologies described above, the main way to improve the strength of stainless steel is by introducing additional precipitates to enhance interfacial strengthening. Similar to precipitation strengthening, pores also provide additional interfaces, which theoretically can effectively hinder the movement of dislocations in the steel, thus generating interfacial strengthening. However, since pores, while providing interfacial strengthening, also result in a loss of volume, thereby reducing the material's strength, micron-sized pores often cannot achieve the desired strengthening effect, which has created a bottleneck in the development of low-density stainless steel materials. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing nanoporous reinforced high-strength, ductile, and low-density stainless steel, overcoming the shortcomings of existing technologies. The method proposes to use stainless steel sintered felt as raw material for repeated rolling and heat treatment, introducing nanopores into the stainless steel material. By utilizing the rich interfaces of the nanopores, the strength of the steel is increased, thereby increasing the strength and reducing the density of the steel while maintaining its ductility.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for preparing nanoporous reinforced high-strength, ductile, low-density stainless steel includes primary rolling, annealing, secondary rolling, and tempering, specifically as follows:

[0009] 1) In a single rolling process, the stainless steel sintered felt is rolled from 3mm to 0.6mm through multiple passes. The initial rolling temperature and the final rolling temperature are both room temperature, and the reduction per pass is 0.25mm.

[0010] 2) Annealing: The stainless steel sintered felt rolled in step 1) is annealed at 1150℃-1250℃, with a heating rate of 1-1.5℃ / s and a holding time of 30-60min.

[0011] Secondary rolling and water cooling quenching: The annealed stainless steel sintered felt in step 2) is subjected to secondary rolling. The initial rolling temperature and the final rolling temperature are both room temperature. It is rolled from 0.6 mm to 0.3 mm in one pass.

[0012] 4) Tempering: The stainless steel after secondary rolling in step 3) is tempered at a temperature of 650℃-1250℃, a heating rate of 1-1.5℃ / s, and a holding time of 0.5-1 hour. After tempering, nanoporous reinforced high-strength, ductile, low-density stainless steel is obtained.

[0013] Furthermore, the stainless steel sintered felt is a three-dimensional network porous material made from micron-sized metal fibers through non-woven laying and high-temperature sintering processes, with a pore size of 0.5-200μm and a porosity of 70-73%.

[0014] Furthermore, the stainless steel sintered felt is compacted through multiple rolling passes in the single rolling process, and the pore size in the sintered felt is refined from 0.5-200μm to 50-200nm.

[0015] Furthermore, the secondary rolling process further refines the pore size in the steel, reducing the pore size in the sintered felt from 50-200 nm to 20-100 nm.

[0016] Furthermore, the stainless steel sintered felt is made of any one of 304, 310S, or 316L.

[0017] Furthermore, the low-density stainless steel obtained from sintered 310S stainless steel felt has a yield strength of 545-590 MPa, an elongation after fracture of 46-52%, and a density of 7180 kg / m³. 3 -7.420 kg / m 3 .

[0018] Furthermore, the low-density stainless steel obtained from sintered 304 stainless steel felt has a yield strength of 580-610 MPa, an elongation after fracture of 42-48%, and a density of 6980 kg / m³. 3 -7.290 kg / m 3 .

[0019] Furthermore, the low-density stainless steel obtained from sintered 316L stainless steel felt has a yield strength of 595-630 MPa, an elongation after fracture of 38-42%, and a density of 7180 kg / m³. 3 -7340 kg / m 3 .

[0020] This invention introduces a large number of nanopores into stainless steel through repeated rolling and heat treatment of sintered felt. Research has shown that these nanopores possess numerous additional interfaces, and the interfacial strengthening they provide outweighs the strength reduction caused by volume loss, successfully increasing the steel's strength. Furthermore, the introduction of these pores significantly reduces the steel's density, resulting in a more pronounced increase in specific strength. Simultaneously, the excellent deformability of these pores ensures that the steel's ductility does not significantly decrease despite the significant increase in specific strength.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1) This invention innovatively introduces nanopores into stainless steel sintered felt. The interface strengthening of nanopores successfully improves the strength of steel. The volume loss caused by the pores reduces the density of steel and further improves the specific strength of steel. The excellent deformation ability of the pores allows the steel to maintain excellent ductility and increases strength while reducing density.

[0023] 2) The nanoporous reinforced stainless steel of the present invention improves the strength by 2.5 times and the specific strength by 2.78 times compared with traditional dense stainless steel without losing plasticity. It enhances the strength-plasticity matching of stainless steel, far exceeding existing stainless steel materials. More importantly, the nanoporous reinforcement mechanism of the present invention provides a new idea for the design of strong plasticity of steel materials. Attached Figure Description

[0024] Figure 1 This is a photograph of the hole morphology in the product of Embodiment 1 of the present invention;

[0025] Figure 2 This is a comparison curve of the tensile strength and plasticity of the product in Example 1 of the present invention and traditional dense stainless steel. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the specific embodiments used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the specific embodiments described below are some embodiments of the present invention. For those skilled in the art, other specific embodiments can be obtained based on these specific embodiments without creative effort.

[0028] The components of the embodiments of the invention described and shown in the specific embodiments herein can be arranged and designed in countless different configurations. Therefore, the following detailed description of the embodiments of the invention provided in the specific embodiments is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0029] In the following embodiments, the stainless steel sintered felt used is a three-dimensional network porous material made from micron-sized metal fibers through non-woven fabrication and high-temperature sintering processes. The pore size is 0.5-200μm and the porosity is 70-73%. The stainless steel sintered felt is made of any one of 304, 310S, or 316L.

[0030] Example 1

[0031] Take the processing of 310S stainless steel sintered felt as an example.

[0032] This invention discloses a method for preparing nanoporous reinforced high-strength, ductile, low-density stainless steel, specifically comprising the following steps:

[0033] 1) One-time rolling: 310S stainless steel sintered felt is rolled at room temperature, and the steel is rolled from 3mm to 0.6mm in three rolling passes;

[0034] 2) Annealing: The rolled 310S stainless steel sintered felt is sintered at 1250℃ for 30 minutes.

[0035] 3) Secondary rolling: The sintered 310S stainless steel felt is rolled at room temperature and rolled from 0.6mm to 0.3mm in one pass.

[0036] 4) Tempering: Temper the 310S stainless steel after secondary rolling at a tempering temperature of 850℃. After tempering, 310S stainless steel with high-density nanopore precipitation is obtained.

[0037] Finally, a nanoporous reinforced 310S stainless steel was obtained, with the pore morphology of the steel as follows: Figure 1 As shown in Table 1, the morphology and density of pores in steel are statistically analyzed. A comparison of the room temperature yield strength and maximum elongation of the steel with Comparative Example 1 is shown in Figure 1. Figure 2As shown in Table 1, the specific properties are as follows. Obviously, compared with the dense 310S stainless steel with the same tempering process (Comparative Example 1), the yield strength of the nanoporous reinforced 310S stainless steel is increased by about 2.6 times and the specific strength is increased by about 2.9 times under the condition of slightly reduced plasticity.

[0038] Example 2

[0039] Take the processing of 310S stainless steel sintered felt as an example.

[0040] This invention discloses a method for preparing nanoporous reinforced high-strength, ductile, low-density stainless steel, specifically comprising the following steps:

[0041] 1) One-time rolling: 310S stainless steel sintered felt is rolled at room temperature, and the steel is rolled from 3mm to 0.6mm in three rolling passes;

[0042] 2) Annealing: The rolled 310S stainless steel sintered felt is sintered at 1250℃ for 30 minutes.

[0043] 3) Secondary rolling: The sintered 310S stainless steel felt is rolled at room temperature and rolled from 0.6mm to 0.3mm in one pass.

[0044] 4) Tempering: Temper the 310S stainless steel after secondary rolling at a tempering temperature of 1050℃. After tempering, 310S stainless steel with high-density nanopore precipitation is obtained.

[0045] A nanoporous reinforced 310S stainless steel was finally obtained. The statistics of pore size, relative density, yield strength, and maximum elongation of the steel are shown in Table 1. Obviously, compared with the dense 310S stainless steel with the same tempering process (Comparative Example 1), the yield strength of the nanoporous reinforced 310S stainless steel is increased by about 2.5 times without sacrificing plasticity, and the specific strength is increased by about 2.8 times.

[0046] Example 3

[0047] Take the processing of 310S stainless steel sintered felt as an example.

[0048] This invention discloses a method for preparing nanoporous reinforced high-strength, ductile, low-density stainless steel, specifically comprising the following steps:

[0049] 1) One-time rolling: 310S stainless steel sintered felt is rolled at room temperature, and the steel is rolled from 3mm to 0.6mm in three rolling passes;

[0050] 2) Annealing: The rolled 310S stainless steel sintered felt is sintered at 1250℃ for 60 minutes.

[0051] 3) Secondary rolling: The sintered 310S stainless steel felt is rolled at room temperature and rolled from 0.6mm to 0.3mm in one pass.

[0052] 4) Tempering: Temper the 310S stainless steel after secondary rolling at a tempering temperature of 850℃. After tempering, 310S stainless steel with high-density nanopore precipitation is obtained.

[0053] Finally, a nanoporous reinforced 310S stainless steel was obtained, with the pore morphology of the steel as follows: Figure 1 As shown in Table 1, the morphology and density of pores in steel are statistically analyzed. A comparison of the room temperature yield strength and maximum elongation of the steel with Comparative Example 1 is shown in Figure 1. Figure 2 As shown in Table 1, the specific properties are as follows. Obviously, compared with the dense 310S stainless steel with the same tempering process (Comparative Example 2), the yield strength of the nanoporous reinforced 310S stainless steel is increased by about 2.9 times and the specific strength is increased by about 3.0 times under the condition of slightly reduced plasticity.

[0054] Example 4

[0055] Take the processing of 310S stainless steel sintered felt as an example.

[0056] This invention discloses a method for preparing nanoporous reinforced high-strength, ductile, low-density stainless steel, specifically comprising the following steps:

[0057] Step 1: Roll the 310S stainless steel sintered felt at room temperature, and roll the steel from 3mm to 0.6mm in three passes;

[0058] 2) Annealing: The rolled 310S stainless steel sintered felt is sintered at 1250℃ for 60 minutes.

[0059] 3) Secondary rolling: The sintered 310S stainless steel felt is rolled at room temperature and rolled from 0.6mm to 0.3mm in one pass.

[0060] 4) Tempering: Temper the 310S stainless steel after secondary rolling at a tempering temperature of 1050℃. After tempering, 310S stainless steel with high-density nanopore precipitation is obtained.

[0061] Finally, a nanoporous reinforced 310S stainless steel was obtained, with the pore morphology of the steel as follows: Figure 1 As shown in Table 1, the morphology and density of pores in steel are statistically analyzed. A comparison of the room temperature yield strength and maximum elongation of the steel with Comparative Example 1 is shown in Figure 1. Figure 2As shown in Table 1, the specific properties are as follows. Obviously, compared with the dense 310S stainless steel with the same tempering process (Comparative Example 2), the yield strength of the nanoporous reinforced 310S stainless steel is increased by about 2.6 times without losing plasticity, and the specific strength is increased by about 2.8 times.

[0062] Example 5

[0063] Take the treatment of 304 stainless steel sintered felt as an example.

[0064] This invention discloses a method for preparing nanoporous reinforced high-strength, ductile, low-density stainless steel, specifically comprising the following steps:

[0065] Step 1: Roll the 304 stainless steel sintered felt at room temperature, and roll the steel from 3mm to 0.6mm in three passes;

[0066] 2) Annealing: The rolled 304 stainless steel sintered felt is sintered at 1250℃ for 30 minutes.

[0067] 3) Secondary rolling: The 304 stainless steel sintered felt after rolling and sintering is rolled a second time at room temperature, and rolled from 0.6mm to 0.3mm in one pass.

[0068] 4) Tempering: Temper the 304 stainless steel after secondary rolling at a tempering temperature of 850℃. After tempering, 304 stainless steel with high-density nanopore precipitation is obtained.

[0069] The final product is a nanoporous reinforced 304 stainless steel, with pore morphology as follows: Figure 1 As shown in Table 1, the morphology and density of pores in steel are statistically analyzed. A comparison of the room temperature yield strength and maximum elongation of the steel with Comparative Example 1 is shown in Figure 1. Figure 2 As shown in Table 1, the specific properties are as follows. Clearly, compared to dense 304 stainless steel with the same tempering process (Comparative Example 3), the yield strength of nanoporous reinforced 304 stainless steel is increased by approximately 2.6 times without sacrificing ductility, and the specific strength is increased by approximately 2.9 times.

[0070] Example 6

[0071] Take the treatment of 304 stainless steel sintered felt as an example.

[0072] This invention discloses a method for preparing nanoporous reinforced high-strength, ductile, low-density stainless steel, specifically comprising the following steps:

[0073] Step 1: Roll the 304 stainless steel sintered felt at room temperature, and roll the steel from 3mm to 0.6mm in three passes;

[0074] 2) Annealing: The rolled 304 stainless steel sintered felt is sintered at 1250℃ for 30 minutes.

[0075] 3) Secondary rolling: The 304 stainless steel sintered felt after rolling and sintering is rolled a second time at room temperature, and rolled from 0.6mm to 0.3mm in one pass.

[0076] 4) Tempering: Temper the 304 stainless steel after secondary rolling at a tempering temperature of 1050℃. After tempering, 304 stainless steel with high-density nanopore precipitation is obtained.

[0077] A nanoporous reinforced 304 stainless steel was finally obtained. The statistics of pore size, relative density, yield strength, and maximum elongation of the steel are shown in Table 1. Obviously, compared with the dense 304 stainless steel with the same tempering process (Comparative Example 3), the yield strength of the nanoporous reinforced 304 stainless steel is increased by about 2.5 times without sacrificing plasticity, and the specific strength is increased by about 2.9 times.

[0078] Example 7

[0079] Take the treatment of 304 stainless steel sintered felt as an example.

[0080] This invention discloses a method for preparing nanoporous reinforced high-strength, ductile, low-density stainless steel, specifically comprising the following steps:

[0081] 1) In a single rolling process, 304 stainless steel sintered felt is rolled at room temperature, and the steel is rolled from 3mm to 0.6mm in three passes.

[0082] 2) Annealing: The rolled 304 stainless steel sintered felt is sintered at 1250℃ for 60 minutes.

[0083] 3) Secondary rolling: The 304 stainless steel sintered felt after rolling and sintering is rolled a second time at room temperature, and rolled from 0.6mm to 0.3mm in one pass.

[0084] 4) Tempering: Temper the 304 stainless steel after secondary rolling at a tempering temperature of 850℃. After tempering, 304 stainless steel with high-density nanopore precipitation is obtained.

[0085] The final product is a nanoporous reinforced 304 stainless steel, with pore morphology as follows: Figure 1 As shown in Table 1, the morphology and density of pores in steel are statistically analyzed. A comparison of the room temperature yield strength and maximum elongation of the steel with Comparative Example 1 is shown in Figure 1. Figure 2 As shown in Table 1, the specific properties are as follows. Obviously, compared with the dense 304 stainless steel with the same tempering process (Comparative Example 4), the yield strength of the nanoporous reinforced 304 stainless steel is increased by about 2.8 times and the specific strength is increased by about 3.0 times under the condition of slightly reduced plasticity.

[0086] Example 8

[0087] Take the treatment of 304 stainless steel sintered felt as an example.

[0088] This invention discloses a method for preparing nanoporous reinforced high-strength, ductile, low-density stainless steel, specifically comprising the following steps:

[0089] 1) In a single rolling process, 304 stainless steel sintered felt is rolled at room temperature, and the steel is rolled from 3mm to 0.6mm in three passes.

[0090] 2) Annealing: The rolled 304 stainless steel sintered felt is sintered at 1250℃ for 60 minutes.

[0091] 3) Secondary rolling: The 304 stainless steel sintered felt after rolling and sintering is rolled a second time at room temperature, and rolled from 0.6mm to 0.3mm in one pass.

[0092] 4) Tempering: Temper the 304 stainless steel after secondary rolling at a tempering temperature of 1050℃. After tempering, 304 stainless steel with high-density nanopore precipitation is obtained.

[0093] The final product is a nanoporous reinforced 304 stainless steel, with pore morphology as follows: Figure 1 As shown in Table 1, the morphology and density of pores in steel are statistically analyzed. A comparison of the room temperature yield strength and maximum elongation of the steel with Comparative Example 1 is shown in Figure 1. Figure 2 As shown in Table 1, the specific properties are as follows. Obviously, compared with the dense 304 stainless steel with the same tempering process (Comparative Example 4), the yield strength of the nanoporous reinforced 304 stainless steel is increased by about 2.9 times without sacrificing plasticity, and the specific strength is increased by about 2.7 times.

[0094] Example 9

[0095] Take the treatment of 316L stainless steel sintered felt as an example.

[0096] This invention discloses a method for preparing nanoporous reinforced high-strength, ductile, low-density stainless steel, specifically comprising the following steps:

[0097] 1) One-time rolling: 316L stainless steel sintered felt is rolled at room temperature, and the steel is rolled from 3mm to 0.6mm in three rolling passes;

[0098] 2) Annealing: The rolled 316L stainless steel sintered felt is sintered at 1250℃ for 30 minutes.

[0099] 3) Secondary rolling: The sintered 316 stainless steel felt is rolled at room temperature and rolled from 0.6 mm to 0.3 mm in one pass.

[0100] 4) Tempering: Temper the 316L stainless steel after secondary rolling at a tempering temperature of 850℃. After tempering, 316 stainless steel with high-density nanopore precipitation is obtained.

[0101] The final product is a nanoporous reinforced 316L stainless steel with a pore morphology as follows: Figure 1 As shown in Table 1, the morphology and density of pores in steel are statistically analyzed. A comparison of the room temperature yield strength and maximum elongation of the steel with Comparative Example 1 is shown in Figure 1. Figure 2 As shown in Table 1, the specific properties are as follows. Clearly, compared to dense 316L stainless steel with the same tempering process (Comparative Example 5), the yield strength of nanoporous reinforced 316L stainless steel is increased by approximately 2.5 times without sacrificing ductility, and the specific strength is increased by approximately 2.8 times.

[0102] Example 10

[0103] Take the treatment of 316L stainless steel sintered felt as an example.

[0104] This invention discloses a method for preparing nanoporous reinforced high-strength, ductile, low-density stainless steel, specifically comprising the following steps:

[0105] 1) One-time rolling: 316L stainless steel sintered felt is rolled at room temperature, and the steel is rolled from 3mm to 0.6mm in three rolling passes;

[0106] 2) Annealing: The rolled 316L stainless steel sintered felt is sintered at 1250℃ for 30 minutes.

[0107] 3) Secondary rolling: The 316L stainless steel sintered felt after rolling and sintering is rolled a second time at room temperature, and rolled from 0.6mm to 0.3mm in one pass.

[0108] 4) Tempering: Temper the 316L stainless steel after secondary rolling at a tempering temperature of 1050℃. After tempering, 316L stainless steel with high-density nanopore precipitation is obtained.

[0109] A nanoporous reinforced 316L stainless steel was finally obtained. The statistics of pore size, relative density, yield strength, and maximum elongation of the steel are shown in Table 1. Obviously, compared with the dense 316L stainless steel with the same tempering process (Comparative Example 5), the yield strength of the nanoporous reinforced 316L stainless steel is increased by about 2.5 times without sacrificing plasticity, and the specific strength is increased by about 2.8 times.

[0110] Example 11

[0111] Take the treatment of 316L stainless steel sintered felt as an example.

[0112] This invention discloses a method for preparing nanoporous reinforced high-strength, ductile, low-density stainless steel, specifically comprising the following steps:

[0113] 1) One-time rolling: 316L stainless steel sintered felt is rolled at room temperature, and the steel is rolled from 3mm to 0.6mm in three rolling passes;

[0114] 2) Annealing: The rolled 316L stainless steel sintered felt is sintered at 1250℃ for 60 minutes.

[0115] 3) Secondary rolling: The 316L stainless steel sintered felt after rolling and sintering is rolled a second time at room temperature, and rolled from 0.6mm to 0.3mm in one pass.

[0116] 4) Tempering: Temper the 316L stainless steel after secondary rolling at a tempering temperature of 850℃. After tempering, 316L stainless steel with high-density nanopore precipitation is obtained.

[0117] The final product is a nanoporous reinforced 316L stainless steel with a pore morphology as follows: Figure 1 As shown in Table 1, the morphology and density of pores in steel are statistically analyzed. A comparison of the room temperature yield strength and maximum elongation of the steel with Comparative Example 1 is shown in Figure 1. Figure 2 As shown in Table 1, the specific properties are as follows. Obviously, compared with the dense 316L stainless steel with the same tempering process (Comparative Example 6), the yield strength of the nanoporous reinforced 316L stainless steel is increased by about 2.7 times without sacrificing plasticity, and the specific strength is increased by about 3.0 times.

[0118] Example 12

[0119] Take the treatment of 316L stainless steel sintered felt as an example.

[0120] This invention discloses a method for preparing nanoporous reinforced high-strength, ductile, low-density stainless steel, specifically comprising the following steps:

[0121] 1) One-time rolling: 316L stainless steel sintered felt is rolled at room temperature, and the steel is rolled from 3mm to 0.6mm in three rolling passes;

[0122] 2) Annealing: The rolled 316L stainless steel sintered felt is sintered at 1250℃ for 60 minutes.

[0123] 3) Secondary rolling: The 316L stainless steel sintered felt after rolling and sintering is rolled a second time at room temperature, and rolled from 0.6mm to 0.3mm in one pass.

[0124] 4) Tempering: Temper the 316L stainless steel after secondary rolling at a tempering temperature of 1050℃. After tempering, 316L stainless steel with high-density nanopore precipitation is obtained.

[0125] The final product is a nanoporous reinforced 316L stainless steel with a pore morphology as follows: Figure 1 As shown in Table 1, the morphology and density of pores in steel are statistically analyzed. A comparison of the room temperature yield strength and maximum elongation of the steel with Comparative Example 1 is shown in Figure 1. Figure 2 As shown in Table 1, the specific properties are as follows. Obviously, compared with the dense 316L stainless steel with the same tempering process (Comparative Example 6), the yield strength of the nanoporous reinforced 316L stainless steel is increased by about 2.6 times and the specific strength is increased by about 2.9 times under the condition of slightly reduced plasticity.

[0126] Comparative Example 1

[0127] Take 310S stainless steel as an example.

[0128] Step 1: Roll 310S stainless steel at room temperature, and roll the steel from 3mm to 0.3mm in four passes;

[0129] Step 2: Temper the rolled 310S stainless steel at a temperature of 850℃ to obtain dense 310S stainless steel.

[0130] The yield strength and maximum elongation of the steel were tested and found to be 225 MPa and 52% respectively for 310S stainless steel tempered at 850℃.

[0131] Comparative Example 2

[0132] Take 310S stainless steel as an example.

[0133] Step 1: Roll 310S stainless steel at room temperature, and roll the steel from 3mm to 0.3mm in four passes;

[0134] Step 2: Temper the rolled 310S stainless steel at a temperature of 1050℃ to obtain dense 310S stainless steel.

[0135] The yield strength and maximum elongation of the steel were tested and found to be 205 MPa and 55% respectively for 310S stainless steel tempered at 1050℃.

[0136] Comparative Example 3

[0137] Take 304 stainless steel as an example.

[0138] Step 1: Roll 304 stainless steel at room temperature, and roll it from 3mm to 0.3mm in four passes;

[0139] Step 2: Temper the rolled 304 stainless steel at a temperature of 850℃ to obtain dense 304 stainless steel.

[0140] The yield strength and maximum elongation of the steel were tested and found to be 235 MPa and 46% respectively for 850℃ tempered dense 304 stainless steel.

[0141] Comparative Example 4

[0142] Take 304 stainless steel as an example.

[0143] Step 1: Roll 304 stainless steel at room temperature, and roll it from 3mm to 0.3mm in four passes;

[0144] Step 2: Temper the rolled 304 stainless steel at a temperature of 1050℃ to obtain dense 304 stainless steel.

[0145] The yield strength and maximum elongation of the steel were tested and found to be 215 MPa and 50% respectively for 304 stainless steel tempered at 1050℃.

[0146] Comparative Example 5

[0147] Take 316L stainless steel as an example.

[0148] Step 1: Roll 316L stainless steel at room temperature, and roll it from 3mm to 0.3mm in four passes.

[0149] Step 2: Temper the rolled 316L stainless steel at a temperature of 850℃ to obtain dense 316L stainless steel.

[0150] The yield strength and maximum elongation of the steel were tested and found to be 245 MPa and 40% respectively for 316L stainless steel tempered at 850℃.

[0151] Comparative Example 6

[0152] Take 304 stainless steel as an example.

[0153] Step 1: Roll 304 stainless steel at room temperature, and roll it from 3mm to 0.3mm in four passes;

[0154] Step 2: Temper the rolled 304 stainless steel at a temperature of 1050℃ to obtain dense 304 stainless steel.

[0155] The yield strength and maximum elongation of the steel were tested and found to be 225 MPa and 45% respectively for 304 stainless steel tempered at 1050℃.

[0156] The steel types, strength, and elongation data in Examples 1-12 and Comparative Examples 1-6 are shown in Table 1.

[0157] Table 1

[0158] Steel grade Hole size / nm density Relative density / % Yield strength / MPa Specific strength Maximum elongation / % Example 1 310S 28 7180 90 590 0.082 46% Example 2 310S 40 7180 90 560 0.078 50% Example 3 310S 26 7420 93 580 0.078 48% Example 4 310S 35 7420 93 545 0.073 52% Example 5 304 30 6980 88 610 0.087 42% Example 6 304 50 6980 88 595 0.085 46% Example 7 304 26 7290 92 600 0.082 45% Example 8 304 45 7290 92 580 0.080 48% Example 9 316 32 7180 90 630 0.088 38% Example 10 316 42 7180 90 615 0.086 40% Example 11 316 28 7340 92 620 0.084 40% Example 12 316 34 7340 92 595 0.081 42% Comparative Example 1 310S / 7980 100 225 0.028 52% Comparative Example 2 310S / 7980 100 205 0.026 55% Comparative Example 3 304 / 7930 100 235 0.030 46% Comparative Example 4 304 / 7930 100 215 0.027 50% Comparative Example 5 316 / 7980 100 245 0.031 40% Comparative Example 6 316 / 7980 100 225 0.028 45%

[0159] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing nanoporous reinforced high-strength, ductile, low-density stainless steel, characterized in that, The process includes primary rolling, annealing, secondary rolling, and tempering, with the following specific steps: 1) A single rolling process is used to roll the stainless steel sintered felt from 3mm to 0.6mm through multiple passes. The initial and final rolling temperatures are both room temperature, and the reduction per pass is 0.25mm. This single rolling process compacts the stainless steel sintered felt through multiple passes, refining the pore size in the sintered felt from 0.5-200μm to 50-200nm. The stainless steel sintered felt is a three-dimensional network porous material made from micron-sized metal fibers through non-woven lay-up and high-temperature sintering processes, with a pore size of 0.5-200μm and a porosity of 70-73%. 2) Annealing: The stainless steel sintered felt rolled in step 1) is annealed at 1150℃-1250℃, with a heating rate of 1-1.5℃ / s and a holding time of 30-60min. 3) Secondary rolling and water-cooled quenching: The annealed stainless steel sintered felt in step 2) is subjected to secondary rolling. The initial rolling temperature and the final rolling temperature are both room temperature. It is rolled from 0.6 mm to 0.3 mm in one pass. The secondary rolling further refines the size of the pores in the steel. The size of the pores in the sintered felt is refined from 50-200 nm to 20-100 nm. 4) Tempering: The stainless steel after secondary rolling in step 3) is tempered at a temperature of 650℃-1250℃, a heating rate of 1-1.5℃ / s, and a holding time of 0.5-1 hour. After tempering, nanoporous reinforced high-strength, ductile, low-density stainless steel is obtained.

2. The method for preparing nanoporous reinforced high-strength, ductile, low-density stainless steel according to claim 1, characterized in that, The stainless steel sintered felt is made of any one of 304, 310S, or 316L.

3. The method for preparing nanoporous reinforced high-strength, ductile, low-density stainless steel according to claim 2, characterized in that, The low-density stainless steel obtained from sintered 310S stainless steel felt has a yield strength of 545-590 MPa, an elongation after fracture of 46-52%, and a density of 7180 kg / m³. 3 -7.420 kg / m 3 .

4. The method for preparing nanoporous reinforced high-strength, ductile, low-density stainless steel according to claim 2, characterized in that, The low-density stainless steel obtained from sintered 304 stainless steel felt has a yield strength of 580-610 MPa, an elongation after fracture of 42-48%, and a density of 6980 kg / m³. 3 -7.290 kg / m 3 .

5. The method for preparing nanoporous reinforced high-strength, ductile, low-density stainless steel according to claim 2, characterized in that, The yield strength of low-density stainless steel obtained from sintered 316L stainless steel felt is 595-630 MPa, the elongation after fracture is 38-42%, and the density is 7180 kg / m3-7340 kg / m3.

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