A high-hardness stainless steel material and its preparation process

Abstract

The present invention relates to the technical field of stainless steel, and discloses a high-hardness stainless steel material and a preparation process thereof. The process includes the following steps: Additive manufacturing: Sandblast and pre-dry the surface of the stainless steel sheet; Using the pretreated stainless steel sheet as a substrate and mixed metal powder A as the raw material for additive manufacturing, under an argon atmosphere, perform selective laser melting additive manufacturing on the surface of the stainless steel, age, and air-cool to obtain additively manufactured stainless steel; Plasma cladding: Grind and pre-treat the surface of the additively manufactured stainless steel; Using the ground and pre-treated additively manufactured stainless steel as a substrate and mixed metal powder B as the raw material for plasma cladding, under an argon atmosphere, perform plasma cladding on the surface of the stainless steel to obtain plasma-cladded stainless steel; Ion nitriding: Grind and pre-treat the surface of the plasma-cladded stainless steel, and perform ion pulse nitriding on the surface of the stainless steel under an argon atmosphere to obtain a high-hardness stainless steel material.

Description

Technical Field

[0001] The present invention relates to the technical field of stainless steel, and specifically to a high-hardness stainless steel material and its preparation process. Background Art

[0002] Stainless steel is a material widely used in various industrial fields and is favored for its excellent corrosion resistance and mechanical strength. 316L stainless steel is widely used in key components such as stone machine tool guides, lead screws, and protective baffles due to its good mechanical properties and excellent corrosion resistance. However, in actual applications, the hardness and wear resistance of 316L stainless steel materials are still insufficient. Especially in high-wear working conditions, such as the strong wear environment generated by stone chips during stone processing, the service life, mechanical properties, and application range of 316L stainless steel are severely limited. A single 316L cladding layer is difficult to meet these stringent working conditions.

[0003] Therefore, improving the hardness and wear resistance of 316L stainless steel is of great significance for expanding its application range and extending its service life. Existing technologies have tried to improve the hardness and wear resistance of stainless steel materials by adjusting the composition ratio and optimizing the heat treatment process, but the effects are still not ideal.

[0004] Therefore, it is of great significance to invent a high-hardness stainless steel material. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-hardness stainless steel material and its preparation process to solve the problems raised in the above background art.

[0006] To solve the above technical problems, the present invention provides the following technical solutions:

[0007] A preparation process of a high-hardness stainless steel material, comprising the following steps:

[0008] S1: Additive manufacturing: Sandblast and preheat the surface of the stainless steel plate; using the pre-treated stainless steel plate as the substrate and mixed metal powder A as the additive manufacturing raw material, under an argon atmosphere, perform selective laser melting additive manufacturing on the stainless steel surface, aging, and air cooling to obtain additive manufacturing stainless steel;

[0009] S2: Plasma cladding: Grind and pre-treat the surface of the additive manufacturing stainless steel; using the ground and pre-treated additive manufacturing stainless steel as the substrate and mixed metal powder B as the plasma cladding raw material, under an argon atmosphere, perform plasma cladding on the stainless steel surface to obtain plasma cladding stainless steel;

[0010] S3: Ion nitriding: Grind and pre-treat the surface of the plasma cladding stainless steel, and perform ion pulse nitriding on the stainless steel surface under an argon atmosphere to obtain a high-hardness stainless steel material.

[0011] Further, in step S1, the preparation method of the mixed metal powder A includes the following steps:

[0012] Add stainless steel powder and niobium metal powder into a ball mill according to the ratio, ball mill and mix the powder, and dry it to obtain the mixed metal powder A.

[0013] Further, the low-carbon stainless steel powder includes 316L stainless steel powder;

[0014] Further, the components of the 316L stainless steel powder include Cr 16.35 wt%, Ni 10.74 wt%, Mo 2.51 wt%, Mn 1.03 wt%, C 0.016 wt%, Si 0.37 wt%, and the balance is Fe.

[0015] Further, in step S1, the components of the stainless steel sheet used as the substrate are the same as those of the metal powder in the mixed metal powder A.

[0016] Further, the stainless steel powder is low-carbon stainless steel powder; in the mixed metal powder A, the mass ratio of the stainless steel powder to the niobium metal powder is (96 - 99):(1 - 4).

[0017] Further, in step S1, the parameters of the selective laser melting additive manufacturing include a laser power of 260 - 280 W, a scanning speed of 960 - 1000 mm / s, a scanning spacing of 0.13 - 0.15 mm, and a powder spreading thickness of 0.04 - 0.06 mm.

[0018] Further, during the selective laser melting additive manufacturing process, the laser deposition direction is perpendicular to the stainless steel substrate, and the scanning direction is parallel to the stainless steel substrate.

[0019] Further, in step S1, the aging temperature is 485 - 505 °C, and the aging time is 4 - 5 h.

[0020] Further, in step S2, the preparation method of the mixed metal powder B includes the following steps:

[0021] Add the metal powder into a ball mill according to the ratio, ball mill and mix the powder, and dry it to obtain the mixed metal powder B;

[0022] Further, the metal powder includes iron, nickel, chromium, and cobalt; in the metal powder, the molar ratio of iron: nickel: chromium: cobalt is 1:1:1:1.

[0023] Further, the particle size of each metal powder in the metal powder is 50 - 100 μm.

[0024] Further, in step S2, the plasma cladding parameters include a cladding speed of 35 - 40 mm / min, a powder feeding rate of 16 - 20 g / min, a working current of 110 A, a working voltage of 35 V, and an argon gas flow rate of 25 - 30 L / min.

[0025] Further, in step S3, the specific operation of the ion pulse nitriding includes placing the plasma - clad stainless steel after grinding pretreatment in a vacuum chamber, passing argon, turning on the filament power supply, adjusting the pulse bias voltage for the first time, and using plasma discharge to perform secondary cleaning on the stainless - steel surface; introducing nitrogen, adjusting the pulse bias voltage for the second time, and controlling the pressure and temperature to perform ion nitriding.

[0026] Further, the ion pulse nitriding parameters include a pulse bias voltage frequency of 60 - 65 kHz, a duty cycle of 80 - 82%; the first - adjusted pulse bias voltages are - 120 V and - 300 V, and the secondary cleaning times are 15 - 20 min and 30 - 45 min respectively; the nitrogen gas flow rate is 200 - 220 sccm; the second - adjusted pulse bias voltage is 500 V - 600 V, the pressure is 0.4 - 0.5 Pa, the temperature is 510 - 520 °C, and the nitriding time is 4 - 5 h.

[0027] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0028] The present invention utilizes the advantages of high alloy density, high precision, and excellent performance in selective laser melting additive manufacturing. It introduces niobium metal powder into 316L stainless - steel powder, and controls the proportion of niobium metal, laser power, and aging temperature during the selective laser melting additive - manufacturing process to control the overall performance of the high - hardness stainless - steel substrate. When introducing niobium metal into the additive - manufacturing process, due to the affinity between niobium element and carbon element, the two elements will first combine to form niobium carbide during the manufacturing process, which hinders the growth of grains at the austenite boundary during the solidification process, making the grains refined, and improving the tensile strength, elongation, and hardness of the stainless - steel material; at the same time, adjusting and reducing the laser power makes the additive - manufactured stainless steel exhibit a cubic tissue structure with a low orientation degree, increasing the cooling rate of the molten pool, further refining the solidification structure, and improving the hardness of the stainless - steel material; finally, through direct aging, niobium carbide precipitation phases with a face - centered cubic crystal structure are precipitated, laying a foundation for subsequent plasma cladding.

[0029] The present invention performs plasma cladding treatment on the surface of stainless steel by configuring a cobalt-iron-nickel-chromium-based high-entropy alloy. On the one hand, the main component of the 316L cladding layer is γ-Fe. When niobium carbide decomposes during the cladding process, the decomposed niobium element dissolves in γ-Fe, causing lattice distortion in the γ-Fe phase, which has a solid-solution strengthening effect. On the other hand, since the atomic radius of niobium is much larger than that of nickel, cobalt, iron, and chromium, it can form a Laves phase with high hardness with the high-entropy alloy (by controlling the proportion of niobium element, avoiding a large amount of Laves phase formation due to excessive niobium element, resulting in reduced toughness and coating cracking; avoiding insufficient niobium element leading to the inability to form Laves phase), greatly improving the hardness of stainless steel. At the same time, lattice distortion enables nitrogen atoms to enter more easily during the subsequent ion nitriding process, increasing the depth and speed of nitriding and promoting the nitriding effect.

[0030] By applying a pulsed bias voltage during the nitriding process, the present invention can diffuse the precipitated chromium atoms on the surface of stainless steel, avoid chromium depletion, and at the same time control the precipitation of niobium carbonitride phase, transforming the nitrided layer from a single layer to a double-layer structure, greatly increasing the thickness of the nitrided layer and further strengthening the hardness and mechanical properties of stainless steel. Detailed implementation mode

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0032] In the following embodiments, the components of 316L stainless steel powder and sheet include Cr 16.35 wt%, Ni 10.74 wt%, Mo 2.51 wt%, Mn 1.03 wt%, C 0.016 wt%, Si 0.37 wt%, and the balance is Fe; the remaining raw materials are all commercially available.

[0033] Embodiment 1: A preparation process for a high-hardness stainless steel material: S1: Additive manufacturing: Sandblast and pre-dry the surface of the 316L sheet; Add 316L powder and niobium metal powder according to a mass ratio of 99:1 to a ball mill, ball-mill and mix the powder, and dry to obtain mixed metal powder A; Using the pre-treated stainless steel sheet as the substrate and mixed metal powder A as the additive manufacturing raw material, perform selective laser melting additive manufacturing on the surface of stainless steel in an argon atmosphere, age at 495°C for 4 h, and air-cool to obtain additive manufacturing stainless steel; Among them, the parameters of selective laser melting additive manufacturing include a laser power of 260 W, a scanning speed of 960 mm / s, a scanning spacing of 0.13 mm, and a powder spreading thickness of 0.04 mm;

[0034] S2: Plasma cladding: The surface of the additive manufacturing stainless steel is polished and pretreated; iron, nickel, chromium, and cobalt are added to a ball mill according to a molar ratio of 1:1:1:1, ball milled and mixed with powder, and dried to obtain mixed metal powder B; using the polished and pretreated additive manufacturing stainless steel as the substrate and mixed metal powder B as the plasma cladding raw material, plasma cladding is carried out on the stainless steel surface under an argon atmosphere to obtain plasma cladded stainless steel; among them, the plasma cladding parameters include a cladding speed of 35 mm / min, a powder feeding rate of 16 g / min, a working current of 110 A, a working voltage of 35 V, and an argon gas flow rate of 25 L / min;

[0035] S3: Ion nitriding: The surface of the plasma cladded stainless steel is polished and pretreated, and ion pulse nitriding is carried out on the stainless steel surface under an argon atmosphere. The polished and pretreated plasma cladded stainless steel is placed in a vacuum chamber. Through argon, the filament power supply is turned on, and the pulse bias voltage is adjusted to -120 V and -300 V for the first time, and the stainless steel surface is cleaned for 15 min and 30 min respectively by plasma discharge; nitrogen with a flow rate of 200 sccm is introduced, the pulse bias voltage is adjusted to 500 V for the second time, the pressure is controlled at 0.4 Pa, and the temperature is 510 °C, and ion nitriding is carried out for 4 h to obtain a high-hardness stainless steel material.

[0036] Example 2: A preparation process for a high-hardness stainless steel material: S1: Additive manufacturing: The surface of the 316L sheet is sandblasted and dried pretreated; 316L powder and niobium metal powder are added to a ball mill according to a mass ratio of 98:2, ball milled and mixed with powder, and dried to obtain mixed metal powder A; using the pretreated stainless steel sheet as the substrate and mixed metal powder A as the additive manufacturing raw material, selective laser melting additive manufacturing is carried out on the stainless steel surface under an argon atmosphere, aged at 495 °C for 4 h, and air-cooled to obtain additive manufacturing stainless steel; among them, the parameters of selective laser melting additive manufacturing include a laser power of 260 W, a scanning speed of 960 mm / s, a scanning pitch of 0.13 mm, and a powder spreading thickness of 0.04 mm;

[0037] The remaining steps are the same as those in Example 1.

[0038] Example 3: A preparation process of a high-hardness stainless steel material: S1: Additive manufacturing: Sandblast and pre-dry the surface of 316L sheet; Add 316L powder and niobium metal powder into a ball mill according to a mass ratio of 97:3, ball-mill and mix the powders, and dry to obtain mixed metal powder A; Using the pre-treated stainless steel sheet as the substrate and mixed metal powder A as the additive manufacturing raw material, under an argon atmosphere, perform selective laser melting additive manufacturing on the stainless steel surface, age at 495°C for 4 hours, and air-cool to obtain additively manufactured stainless steel; Among them, the parameters of selective laser melting additive manufacturing include a laser power of 260W, a scanning speed of 960mm / s, a scanning spacing of 0.13mm, and a powder spreading thickness of 0.04mm;

[0039] The remaining steps are the same as those in Example 1.

[0040] Example 4: A preparation process of a high-hardness stainless steel material: S1: Additive manufacturing: Sandblast and pre-dry the surface of 316L sheet; Add 316L powder and niobium metal powder into a ball mill according to a mass ratio of 96:4, ball-mill and mix the powders, and dry to obtain mixed metal powder A; Using the pre-treated stainless steel sheet as the substrate and mixed metal powder A as the additive manufacturing raw material, under an argon atmosphere, perform selective laser melting additive manufacturing on the stainless steel surface, age at 495°C for 4 hours, and air-cool to obtain additively manufactured stainless steel; Among them, the parameters of selective laser melting additive manufacturing include a laser power of 260W, a scanning speed of 960mm / s, a scanning spacing of 0.13mm, and a powder spreading thickness of 0.04mm;

[0041] The remaining steps are the same as those in Example 1.

[0042] Example 5: A preparation process of a high-hardness stainless steel material: S3: Ion nitriding: Grind and pre-treat the surface of plasma cladded stainless steel, under an argon atmosphere, perform ion pulse nitriding on the stainless steel surface, place the pre-treated plasma cladded stainless steel in a vacuum chamber, pass argon, turn on the filament power supply, first adjust the pulse bias voltage to -120V and -300V, and use plasma discharge to clean the stainless steel surface for 15 minutes and 30 minutes respectively; Introduce nitrogen with a flow rate of 200sccm, second adjust the pulse bias voltage to 600V, control the pressure to 0.4Pa, and the temperature to 510°C, and perform ion nitriding for 4 hours to obtain a high-hardness stainless steel material;

[0043] The remaining steps are the same as those in Example 1.

[0044] Comparative Example 1: A preparation process of a high-hardness stainless steel material: S1: Additive manufacturing: Sandblast and pre-dry the surface of 316L sheet; Add 316L powder and niobium metal powder into a ball mill according to a mass ratio of 99.5:0.5, ball mill and mix the powders, and dry to obtain mixed metal powder A; Using the pretreated stainless steel sheet as the substrate and mixed metal powder A as the additive manufacturing raw material, under an argon atmosphere, perform selective laser melting additive manufacturing on the stainless steel surface, age at 495°C for 4h, and air cool to obtain additively manufactured stainless steel; Among them, the parameters of selective laser melting additive manufacturing include a laser power of 260W, a scanning speed of 960mm / s, a scanning spacing of 0.13mm, and a powder spreading thickness of 0.04mm;

[0045] The remaining steps are the same as those in Example 1.

[0046] Comparative Example 2: A preparation process of a high-hardness stainless steel material: S1: Additive manufacturing: Sandblast and pre-dry the surface of 316L sheet; Add 316L powder and niobium metal powder into a ball mill according to a mass ratio of 95:5, ball mill and mix the powders, and dry to obtain mixed metal powder A; Using the pretreated stainless steel sheet as the substrate and mixed metal powder A as the additive manufacturing raw material, under an argon atmosphere, perform selective laser melting additive manufacturing on the stainless steel surface, age at 495°C for 4h, and air cool to obtain additively manufactured stainless steel; Among them, the parameters of selective laser melting additive manufacturing include a laser power of 260W, a scanning speed of 960mm / s, a scanning spacing of 0.13mm, and a powder spreading thickness of 0.04mm;

[0047] The remaining steps are the same as those in Example 1.

[0048] Comparative Example 3: A preparation process of a high-hardness stainless steel material: S1: Additive manufacturing: Sandblast and pre-dry the surface of 316L sheet; Add 316L powder and niobium metal powder into a ball mill according to a mass ratio of 99:1, ball mill and mix the powders, and dry to obtain mixed metal powder A; Using the pretreated stainless steel sheet as the substrate and mixed metal powder A as the additive manufacturing raw material, under an argon atmosphere, perform selective laser melting additive manufacturing on the stainless steel surface, perform tissue adjustment at 780°C for 1h, age at 495°C for 4h, and air cool to obtain additively manufactured stainless steel; Among them, the parameters of selective laser melting additive manufacturing include a laser power of 260W, a scanning speed of 960mm / s, a scanning spacing of 0.13mm, and a powder spreading thickness of 0.04mm;

[0049] The remaining steps are the same as those in Example 1.

[0050] Comparative Example 4: A preparation process of a high-hardness stainless steel material: S1: Additive manufacturing: Sandblast and pre-dry the surface of 316L sheet; Add 316L powder and niobium metal powder into a ball mill according to a mass ratio of 99:1, ball-mill and mix the powders, and dry to obtain mixed metal powder A; Using the pre-treated stainless steel sheet as the substrate and mixed metal powder A as the additive manufacturing raw material, under an argon atmosphere, perform selective laser melting additive manufacturing on the stainless steel surface, perform tissue solution at 1040°C for 1 h, age at 495°C for 4 h, and air-cool to obtain additively manufactured stainless steel; Among them, the parameters of selective laser melting additive manufacturing include a laser power of 260 W, a scanning speed of 960 mm / s, a scanning spacing of 0.13 mm, and a powder spreading thickness of 0.04 mm;

[0051] The remaining steps are the same as those in Example 1.

[0052] Comparative Example 5: A preparation process of a high-hardness stainless steel material: S1: Additive manufacturing: Sandblast and pre-dry the surface of 316L sheet; Add 316L powder and niobium metal powder into a ball mill according to a mass ratio of 99:1, ball-mill and mix the powders, and dry to obtain mixed metal powder A; Using the pre-treated stainless steel sheet as the substrate and mixed metal powder A as the additive manufacturing raw material, under an argon atmosphere, perform selective laser melting additive manufacturing on the stainless steel surface, age at 495°C for 4 h, and air-cool to obtain additively manufactured stainless steel; Among them, the parameters of selective laser melting additive manufacturing include a laser power of 260 W, a scanning speed of 960 mm / s, a scanning spacing of 0.13 mm, and a powder spreading thickness of 0.04 mm;

[0053] S2: Ion nitriding: Grind and pre-treat the surface of the plasma cladded stainless steel, and perform ion pulse nitriding on the stainless steel surface under an argon atmosphere. Place the pre-ground and pre-treated plasma cladded stainless steel in a vacuum chamber, pass argon, turn on the filament power supply, and adjust the pulse bias voltage to -120 V and -300 V for the first time, and use plasma discharge to clean the stainless steel surface for 15 min and 30 min respectively; Introduce nitrogen with a flow rate of 200 sccm, adjust the pulse bias voltage to 500 V for the second time, control the pressure to 0.4 Pa, and the temperature to 510°C, and perform ion nitriding for 4 h to obtain a high-hardness stainless steel material.

[0054] Comparative Example 6: A preparation process of a high-hardness stainless steel material: S3: Ion nitriding: Grind and pre-treat the surface of the plasma cladded stainless steel, and perform low-temperature plasma nitriding on the stainless steel surface under an argon atmosphere. The parameters of low-temperature plasma nitriding are a voltage of 520 V, a pressure of 10 Pa, the gas is composed of hydrogen and nitrogen with a volume ratio of 3:1, a temperature of 420°C, a furnace pressure of 240 Pa, and a time of 5 h to obtain a high-hardness stainless steel material;

[0055] The remaining steps are the same as those in Example 1.

[0056] Comparative Example 7: A preparation process of a high-hardness stainless steel material: S3: Ion nitriding: The surface of the plasma-clad stainless steel is polished and pretreated. In an argon atmosphere, ion pulse nitriding is carried out on the surface of the stainless steel. The pretreated plasma-clad stainless steel is placed in a vacuum chamber. Through argon, the filament power supply is turned on. The pulse bias voltage is adjusted to -120V and -300V for the first time, and the surface of the stainless steel is cleaned by plasma discharge for 15 min and 30 min respectively; Nitrogen with a flow rate of 200 sccm is introduced, the pulse bias voltage is adjusted to 400V for the second time, the pressure is controlled at 0.4 Pa, and the temperature is 510 °C, and ion nitriding is carried out for 4 h to obtain a high-hardness stainless steel material;

[0057] The remaining steps are the same as those in Example 1.

[0058] Comparative Example 8: A preparation process of a high-hardness stainless steel material: S1: Additive manufacturing: The surface of the 316L sheet is sandblasted and pre-baked; Using the pretreated stainless steel sheet as the substrate and 316L powder as the additive manufacturing raw material, selective laser melting additive manufacturing is carried out on the surface of the stainless steel in an argon atmosphere, aged at 495 °C for 4 h, and air-cooled to obtain additively manufactured stainless steel; Among them, the parameters of selective laser melting additive manufacturing include a laser power of 260 W, a scanning speed of 960 mm / s, a scanning spacing of 0.13 mm, and a powder laying thickness of 0.04 mm;

[0059] S2: Plasma cladding: The surface of the additively manufactured stainless steel is polished and pretreated; Iron, nickel, chromium, cobalt, and niobium are added to a ball mill according to a molar ratio of 1:1:1:1:0.5, ball-milled and mixed with powder, and dried to obtain mixed metal powder B; Using the polished and pretreated additively manufactured stainless steel as the substrate and mixed metal powder B as the plasma cladding raw material, plasma cladding is carried out on the surface of the stainless steel in an argon atmosphere to obtain plasma-clad stainless steel; Among them, the plasma cladding parameters include a cladding speed of 35 mm / min, a powder feeding rate of 16 g / min, a working current of 110 A, a working voltage of 35 V, and an argon gas flow rate of 25 L / min;

[0060] S3: Ion nitriding: The surface of the plasma-clad stainless steel is polished and pretreated. In an argon atmosphere, ion pulse nitriding is carried out on the surface of the stainless steel. The pretreated plasma-clad stainless steel is placed in a vacuum chamber. Through argon, the filament power supply is turned on. The pulse bias voltage is adjusted to -120V and -300V for the first time, and the surface of the stainless steel is cleaned by plasma discharge for 15 min and 30 min respectively; Nitrogen with a flow rate of 200 sccm is introduced, the pulse bias voltage is adjusted to 500V for the second time, the pressure is controlled at 0.4 Pa, and the temperature is 510 °C, and ion nitriding is carried out for 4 h to obtain a high-hardness stainless steel material.

[0061] Comparative Example 9: A preparation process of a high-hardness stainless steel material: S1: Additive manufacturing: Sandblast and pre-dry the surface of 316L sheet; Add 316L powder and niobium metal powder into a ball mill according to a mass ratio of 99:1, ball mill and mix the powders, and dry to obtain mixed metal powder A; Using the pre-treated stainless steel sheet as the substrate and mixed metal powder A as the additive manufacturing raw material, under an argon atmosphere, perform selective laser melting additive manufacturing on the stainless steel surface, age at 495°C for 4h, and air cool to obtain additively manufactured stainless steel; Among them, the parameters of selective laser melting additive manufacturing include a laser power of 320W, a scanning speed of 960mm / s, a scanning spacing of 0.13mm, and a powder spreading thickness of 0.04mm;

[0062] Experiment: Microhardness test: It is carried out using a microhardness tester with a load of 500g, a loading time of 10s, and a cone angle of 130°;

[0063] The calculation formula is HV = 0.102×2PSin(α / 2) / d 2 ;

[0064] Among them, P is the load, α is the cone angle of the diamond indenter, and d is the average value of the indentation diagonal length.

[0065] Room temperature tensile property test:

[0066] Test according to the method of GB / T228.1-2010, use a universal testing machine, set the tensile rate to 0.5mm / min, use a computer to record the displacement-load curve, and convert it into a stress-strain curve to calculate the tensile strength and elongation of the material; In order to more intuitively reflect the difference in data, based on the tensile strength and elongation measured in Example 1, the remaining examples and comparative examples only show the percentage of the difference from Example 1 in the data table.

[0067] R = F / S0;

[0068] Among them, R is the stress, F is the load, and S0 is the cross-sectional area of the gauge section of the tensile specimen;

[0069] Σ = (L1 - L0) / L0;

[0070] Among them, Σ is the material strain, L1 is the gauge length after fracture, and L0 is the original gauge length.

[0071] Table 1 Data table of high-hardness stainless steel performance test

[0072]

[0073] Conclusion: The high-hardness stainless steel prepared by the present invention has excellent mechanical properties and hardness.

[0074] In Comparative Example 1, the proportion of niobium metal powder is too small. The insufficient niobium element causes the Laves phase not to form, resulting in performance degradation. In Comparative Example 2, the proportion of niobium metal powder is too large. The excessive niobium element causes a large amount of Laves phase to form, reducing toughness and causing the coating to crack, resulting in performance degradation. In Comparative Example 3, the aging process is adjusted. A microstructure adjustment at 780°C for 1 h is added before aging at 495°C, resulting in performance degradation. In Comparative Example 4, the aging process is adjusted. A solution treatment of the microstructure at 1040°C for 1 h is added before aging at 495°C, resulting in performance degradation. In Comparative Example 5, the plasma cladding step is missing, resulting in performance degradation. In Comparative Example 6, low-temperature ion nitriding is used to replace pulsed ion nitriding. The nitriding rate is low and the thickness of the nitrided layer is thin, resulting in performance degradation. In Comparative Example 7, the second adjustment of the pulsed bias voltage is too low, with a single-layer nitrided layer structure and a reduced thickness of the nitrided layer, resulting in performance degradation. In Comparative Example 8, a traditional method of surface cladding with niobium is used to prepare high-hardness stainless steel, with a reduced degree of lattice refinement, resulting in performance degradation. In Comparative Example 9, the laser power in selective laser melting additive manufacturing is too high, resulting in an increased molten pool lifetime, a reduced cooling rate, a longer solidification time, and a reduced degree of lattice refinement, resulting in performance degradation.

[0075] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A process for preparing high hardness stainless steel material, characterized in that: The following steps are involved: S1: Additive manufacturing: The surface of the stainless steel plate is pre-treated by sandblasting and drying; the pre-treated stainless steel plate is used as a substrate, and the mixed metal powder A is used as an additive manufacturing raw material. In an argon atmosphere, the stainless steel surface is selectively laser melted for additive manufacturing, aging, and air cooling to obtain additively manufactured stainless steel; S2: Plasma cladding: The surface of the additively manufactured stainless steel is pre-treated by grinding; the pre-treated additively manufactured stainless steel is used as a substrate, and the mixed metal powder B is used as a plasma cladding raw material. In an argon atmosphere, the stainless steel surface is plasma clad to obtain plasma clad stainless steel; S3: Ion nitriding: The plasma clad stainless steel surface is pre-treated by grinding, and then ion pulse nitriding is performed on the stainless steel surface in an argon atmosphere to obtain a high-hardness stainless steel material; In step S1, the method for preparing the mixed metal powder A comprises the following steps: adding stainless steel powder and niobium metal powder into a ball mill according to a ratio, ball milling and mixing the powders, and drying to obtain the mixed metal powder A; The stainless steel powder is a low-carbon stainless steel powder; in the mixed metal powder A, the mass ratio of the stainless steel powder to the niobium metal powder is (96-99):(1-4); In step S2, the preparation method of the mixed metal powder B comprises the following steps: adding metal powders into a ball mill according to a ratio, ball milling and mixing the powders, and drying to obtain a mixed metal powder B; the mixed metal powder B comprises iron, nickel, chromium, and cobalt; in the mixed metal powder B, the molar ratio of iron: nickel: chromium: cobalt is 1:1:1:1; In step S3, the specific operation of ion pulse nitriding includes placing the plasma-clad stainless steel after grinding pretreatment in a vacuum chamber, passing argon gas, turning on the filament power supply, adjusting the pulse bias voltage for the first time, and performing secondary cleaning of the stainless steel surface by plasma discharge; passing nitrogen gas, adjusting the pulse bias voltage for the second time, controlling the pressure and temperature, and performing ion nitriding.

2. The process for preparing a high-hardness stainless steel material according to claim 1, characterized in that: In step S1, the parameters of the selective laser melting additive manufacturing include: laser power of 260-280 W, scanning speed of 960-1000 mm / s, scanning spacing of 0.13-0.15 mm, and powder thickness of 0.04-0.06 mm.

3. The process for preparing a high-hardness stainless steel material according to claim 1, characterized in that: In step S1, the aging temperature is 485-505°C, and the aging time is 4-5h.

4. The process for preparing a high-hardness stainless steel material according to claim 1, characterized in that: In step S2, the plasma cladding parameters include a cladding speed of 35-40 mm / min, a powder feeding rate of 16-20 g / min, a working current of 110 A, a working voltage of 35 V, and an argon gas flow rate of 25-30 L / min.

5. The process for preparing a high hardness stainless steel material according to claim 1, characterized in that: The ion pulse nitriding parameters include: a pulse bias frequency of 60-65kHz and a duty cycle of 80-82%; the first pulse bias is adjusted to -120V and -300V, and the secondary cleaning time is 15-20min and 30-45min respectively; the nitrogen flow rate is 200-220sccm; the second pulse bias is adjusted to 500V-600V, the pressure is 0.4-0.5Pa, the temperature is 510-520℃, and the nitriding time is 4-5h.

6. High hardness stainless steel prepared according to the preparation process of a high hardness stainless steel material according to any one of claims 1 to 5.

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