High-boron austenitic stainless steel powder for laser additive manufacturing and preparation method thereof

Abstract

The application relates to a high-boron austenitic stainless steel powder for laser additive manufacturing and a preparation method, wherein the high-boron austenitic stainless steel powder for laser additive manufacturing is composed of the following components in percentage by mass: C: <=0.04%, Si: 0.3-1.0%, Cr: 19-22%, Ni: 11-15%, Mn: 1.2-3.0%, B: 0.8-1.6%, N<=0.01%, O<=0.04%, S<=0.02%, P<=0.02%, and Fe is the balance. The high-boron austenitic stainless steel powder has good loose bulk density, tap density and fluidity, the tensile strength of the obtained high-boron austenitic stainless steel powder in a laser additive manufacturing accumulated state can reach more than 950 MPa, the elongation after fracture is more than 14%, meanwhile, the high-boron austenitic stainless steel powder has good local pitting corrosion resistance, and is suitable for complex components and integral forming in the fields of spent fuel treatment and transportation container manufacturing.

Description

Technical Field

[0001] This invention belongs to the field of materials technology for laser additive manufacturing, specifically relating to a high-boron austenitic stainless steel powder for laser additive manufacturing and its preparation method. Background Technology

[0002] High-boron austenitic stainless steel (boron content ≥0.1%) is widely used in spent fuel storage devices, such as spent fuel racks and storage containers, due to its excellent neutron absorption and radiation shielding capabilities. However, since the solid solubility of boron in austenite is below 0.01%, excessively high boron content leads to the precipitation of large-sized, high-hardness borides, such as (Cr,Fe)₂B, in austenitic stainless steel. These large-sized borides increase the inhomogeneity of composition and microstructure, causing a significant decrease in strength and corrosion resistance. On the other hand, to improve storage density and enhance radiation shielding and neutron absorption capabilities, spent fuel storage or shielding components often employ complex structures, such as grid structures and irregularly shaped pipeline structures. Currently, these complex components are mainly manufactured using welding or powder metallurgy processes, but these methods suffer from problems such as long supply chains, long production cycles, low material utilization, and low yield rates. Furthermore, the achievable structural complexity is limited, restricting the application of high-boron austenitic stainless steel components in the manufacture of spent fuel storage and transport containers.

[0003] In recent years, the rapid development of laser additive manufacturing technology has provided a new paradigm and opportunities for the manufacture of complex components made of high-boron austenitic stainless steel. Compared with traditional casting and forging processes, laser additive manufacturing eliminates the need for molds, has high material utilization, and enables rapid overall forming of complex components. Furthermore, during laser additive manufacturing, the material undergoes rapid heating, rapid solidification, and multiple thermal cycles, inducing the formation of a nanoscale non-equilibrium solidified cellular structure in the matrix. This structure helps promote the formation of a passivation film, reduces the number of pitting corrosions, and inhibits metal dissolution within the pits, thus giving laser-added austenitic stainless steel excellent strength and pitting corrosion resistance. However, currently, during the laser additive manufacturing process, a large amount of boride / austenitic eutectic phase is generated between dendrites in the later stages of solidification of high-boron austenitic stainless steel powder. Under additive stress, these eutectic phases easily cause microcracks or even cracking, leading to a decrease in the strength and plasticity of the additive components, as well as a decrease in corrosion resistance (especially pitting corrosion resistance), making it difficult to meet service requirements.

[0004] Therefore, the development of high-strength, pitting-resistant, high-boron austenitic stainless steel powder materials suitable for laser additive manufacturing has significant engineering application value. Summary of the Invention

[0005] The first technical problem to be solved by the present invention is to provide a high-boron austenitic stainless steel powder for laser additive manufacturing, in order to improve the strength and corrosion resistance of additive components, in light of the current state of the prior art.

[0006] The second technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned high-boron austenitic stainless steel powder for laser additive manufacturing.

[0007] The technical solution adopted by the present invention to solve the first technical problem mentioned above is: a high-boron austenitic stainless steel powder for laser additive manufacturing, characterized in that: by mass percentage, it is composed of the following components: C: ≤0.04%, Si: 0.3-1.0%, Cr: 19-22%, Ni: 11-15%, Mn: 1.2-3.0%, B: 0.8-1.6%, N≤0.01%, O≤0.04%, S≤0.02%, P≤0.02%, and Fe as the balance.

[0008] The functions of each component in the high-boron austenitic stainless steel powder of the present invention are as follows:

[0009] C: Interstitial solid solution strengthening element. It helps improve the strength of high-boron austenitic stainless steel, but excessive carbon content will cause carbide precipitation during additive manufacturing, leading to chromium-depleted zones, thereby reducing the material's corrosion resistance and impairing the component's plasticity. Therefore, in this invention, the carbon content is strictly controlled to ≤0.04%.

[0010] In laser additive manufacturing, silicon acts as a highly efficient deoxidizer, helping to improve molten pool fluidity and enhance component forming quality. However, when the silicon content exceeds a certain critical value, its negative effects become apparent: on the one hand, excessive silicon easily forms low-melting-point silicon oxide inclusions during forming, remaining in the molten pool and reducing its purity; on the other hand, silicon has a synergistic effect with boron, exacerbating the intrinsic brittleness and crack susceptibility of the material. Therefore, this invention strictly controls the silicon content within the range of 0.3% to 1.0%.

[0011] Cr: Chromium is a key element for improving the corrosion resistance of materials. In additive manufacturing, it participates in the formation of a stable passivation film and dissolves in the austenitic matrix, thereby improving the material's corrosion resistance and strength. However, when the chromium content is too high, the chromium in the molten pool will undergo a metallurgical reaction with boron, generating a large number of coarse and brittle boride phases. These brittle phases not only deteriorate the material's toughness but may also become the source of crack initiation and propagation, thus adversely affecting the overall mechanical properties. Therefore, in this invention, the chromium content is controlled within the range of 19-22%.

[0012] Ni: As an austenite stabilizing element, Ni plays a crucial role in regulating the microstructure and properties of high-boron austenitic stainless steel. By promoting and stabilizing the austenite matrix, it effectively enhances the material's plasticity and toughness, thereby partially offsetting the embrittlement tendency caused by high boron content and boride precipitation. Therefore, in this invention, the Ni content is controlled within the range of 11-15%.

[0013] Mn: Mn and Si can undergo a complex deoxidation process, forming oxides with low density that easily float out of the molten pool. However, when the manganese content is too high, a large number of inclusions are generated during continuous additive manufacturing. These inclusions are difficult to float to the surface and be discharged quickly from the molten pool, thus remaining inside the material and causing a significant decrease in material properties. Therefore, the Mn content in this invention is controlled at 1.2% to 3.0%.

[0014] B: The addition of boron (B) is to endow austenitic stainless steel with thermal neutron absorption and radiation shielding capabilities. During the solidification process of laser additive manufacturing, boron exhibits a significant tendency to segregate, easily leading to compositional supercooling under rapid cooling conditions, thus promoting grain refinement. Simultaneously, boron readily combines with elements such as chromium and iron to form fine boride phases dispersed within the austenitic matrix, resulting in a significant precipitation strengthening effect and enhancing material strength. However, excessive boron content leads to the formation of excessive coarse borides. On one hand, these borides consume a large amount of chromium, a key corrosion-resistant element in the matrix, resulting in increased pitting corrosion susceptibility and decreased corrosion resistance. On the other hand, excessive brittle phases drastically increase the material's crack susceptibility, worsening formability during laser additive manufacturing. Conversely, if the boron content is too low, it is difficult to meet the expected requirements for a high thermal neutron absorption cross-section, resulting in insufficient radiation resistance and limited strength improvement. Therefore, in this invention, the boron content is controlled within the range of 0.8% to 1.6%.

[0015] Impurity elements such as N, O, P, and S: N combines with Cr in steel to form nitrides, exacerbating chromium depletion in the matrix and directly impairing the material's pitting corrosion resistance. Furthermore, in laser additive manufacturing, nitrogen readily induces porosity defects, and high-boron systems are already sensitive to porosity; excessive nitrogen significantly exacerbates this forming problem. O forms oxide inclusions that harm strength and pitting corrosion resistance. P and S are harmful elements; they mainly accumulate at grain boundaries, reducing grain boundary strength, leading to a decrease in overall material strength, and potentially increasing the tendency for hot cracking. Therefore, the alloy composition design and atomization process of high-boron austenitic stainless steel spherical powder require strict control of the content of these impurity elements. In this invention, the N content is controlled at ≤0.01%, the O content at ≤0.04%, and the S and P contents at ≤0.02%.

[0016] By employing the above elemental ratios, precise control and synergistic strengthening mechanisms are achieved in the solidification process of the laser additive manufacturing melt pool. During the rapid solidification process in laser additive manufacturing, C, Ni, Cr, and Mn preferentially dissolve in the austenitic matrix, playing a solid solution strengthening role and ensuring the intrinsic strength and stability of the matrix. Simultaneously, Cr and B segregate in the interdendritic region and precipitate nanoscale borides in situ, thereby achieving a dual effect of second-phase strengthening and grain refinement, effectively improving the strength and toughness matching of the material. In addition, the addition of Si optimizes the melt flowability, improves the forming quality and microstructure uniformity. More importantly, this composition design, while precipitating nanoscale borides during the rapid cooling process of laser additive manufacturing, does not excessively consume the Cr content in the matrix, thus retaining sufficient Cr to meet the requirements of pitting corrosion resistance. Therefore, the composition system of this invention, through the synergistic effect of multiple mechanisms, takes into account the formability, mechanical properties, and resistance to localized corrosion of the material under laser additive manufacturing processes. The elemental ratio design is scientifically sound and has engineering application potential.

[0017] Preferably, the powder has an average particle size of 15-53 μm, a flowability of 20-28 s / 50 g, and a bulk density of 4.1-5.8 g / cm³. 3 The tap density is 4.5~6.0 g / cm³. 3 .

[0018] The technical solution adopted by the present invention to solve the second technical problem mentioned above is as follows: a method for preparing high-boron austenitic stainless steel powder for laser additive manufacturing as described above, characterized by the following steps:

[0019] 1) Making bar stock: The high boron austenitic stainless steel is prepared by batching according to the composition of the high boron austenitic stainless steel, and then vacuum induction melting, electrode casting, forging and machining are carried out in sequence to prepare high boron austenitic stainless steel bars.

[0020] 2) Gas atomization powder making: The prepared high boron austenitic stainless steel bar is fed into the feeding mechanism of the electrode induction melting inert gas atomization equipment for gas atomization powder making to obtain high boron austenitic stainless steel powder.

[0021] 3) Powder post-treatment: The obtained high-boron austenitic stainless steel powder is classified and dried.

[0022] In step 1), no specific limitations are made on the process parameters for vacuum induction melting, electrode casting, forging, and machining. Those skilled in the art can select them according to the actual situation.

[0023] Preferably, in step 1), the diameter of the high-boron austenitic stainless steel bar is 50~70mm.

[0024] Preferably, in step 2), the rotation speed of the high-boron austenitic stainless steel bar is 5~25 rpm during gas atomization.

[0025] Preferably, in step 2), the inert gas used for atomization is argon.

[0026] Preferably, in step 2), the nozzle structure of the atomizing device is a restricted nozzle. Restricted nozzles are existing technology, and their specific structure will not be described in detail.

[0027] Furthermore, in step 2), the pressure of the atomizing gas is 2~5MPa, and the feed rate of the atomizing gas is 0.5~1.2mm / s.

[0028] Further, in step 3), the powder is classified using a vibrating sieve to screen out powder with a particle size of 15~53μm; the powder that meets the particle size requirements is dried for 3~5 hours.

[0029] Compared with existing technologies, the advantages of this invention are as follows: The high-boron austenitic stainless steel powder composition system of this invention is scientifically and rationally designed, generating a significant non-equilibrium solidification effect during the rapid solidification process of laser additive manufacturing, thereby inducing significant compositional supercooling. This effect promotes the formation of nanoscale dendritic structures within the molten pool and drives borides to be dispersed in the interdendritic region in the form of particles with a size of approximately 20-100 nm. The combined effect of nanodendritic structures and dispersed borides results in a tensile strength of over 950 MPa and an elongation exceeding 14%. Secondly, the nanoscale borides are mainly distributed in the chromium-rich interdendritic regions, minimizing their destructive effect on the stability and integrity of the surface passivation film. Therefore, the material exhibits a high breakdown potential exceeding 0.2 V (vs. SCE) in the potentiodynamic polarization curve of 3.5% NaCl solution, significantly improving pitting corrosion resistance. Furthermore, the preparation method of this invention is simple and easy to operate, and the prepared high-boron austenitic stainless steel powder has good bulk density, tap density, and flowability. During laser additive manufacturing, this powder exhibits excellent process stability, with thorough melting and uniform melt flow and spreading, which greatly improves the forming quality. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the potentiodynamic polarization test specimen and the tensile specimen of the high-boron austenitic stainless steel prepared in the embodiments of the present invention.

[0031] Figure 2 This is a dimensional diagram of a tensile specimen of high-boron austenitic stainless steel prepared according to an embodiment of the present invention. The dimensions are in mm. Detailed Implementation Example 1

[0032] A laser additive manufacturing method for high-boron austenitic stainless steel powder, wherein the high-boron austenitic stainless steel powder is prepared by gas atomization into a combination of multiple components, and the mass percentage of its chemical composition is as follows:

[0033] C: 0.025%, Si: 0.68%, Cr: 21.6%, Ni: 13.52%, Mn: 2.46%, B: 1.44%, N: 0.006%, O: 0.01%, S: 0.01%, P: 0.01%, Fe is the balance.

[0034] The high-boron austenitic stainless steel powder has an average particle size of 15~53μm, a flowability of 25.5s / 50g, and a loose packing density of 4.53g / cm³. 3 The tap density is 5.26 g / cm³. 3 .

[0035] The preparation steps of high-boron austenitic stainless steel powder for laser additive manufacturing are as follows:

[0036] (1) Making bar stock: The high boron austenitic stainless steel is prepared according to the target composition of the high boron austenitic stainless steel, and then vacuum induction melting, electrode casting, forging and machining are carried out in sequence to obtain high boron austenitic stainless steel bar stock with a diameter of 55mm; the process parameters of vacuum induction melting, electrode casting, forging and machining are not specifically limited and can be selected according to the actual situation;

[0037] (2) Gas atomization powder making: The obtained high boron austenitic stainless steel bar is fed into the feeding mechanism of the electrode induction melting inert gas atomization equipment and gas atomization powder making is carried out under argon to obtain high boron austenitic stainless steel powder. During gas atomization, the rotation speed of the high boron austenitic stainless steel bar is 20 rpm; the atomizing gas pressure is 3 MPa and the atomizing gas feed rate is 0.6 mm / s; the nozzle structure of the gas atomization equipment is a restricted nozzle.

[0038] (3) Powder post-treatment: The obtained high boron austenitic stainless steel powder is classified by a vibrating screener to screen out powder with a particle size of 15~53μm. Then, the powder that meets the particle size requirements is placed in a low temperature vacuum drying equipment and dried for 3.5h.

[0039] Selective laser melting (SLM) was used to perform forming experiments on high-boron austenitic stainless steel. The forming process parameters were set as follows: laser power 400W, scanning distance 0.04mm, and scanning speed 220mm / s. Under these parameters, additive manufacturing was performed on block specimens with dimensions of 10mm×10mm×10mm and standard plate tensile specimens, such as... Figure 1 , 2 As shown. During the room temperature tensile property test, three measurements were performed and the average value was calculated. The pitting potential was determined by potentiodynamic polarization, with an electrode area of ​​0.25 cm². 2The test used a 3.5 wt.% NaCl solution without deoxygenation, and polarized at a constant potential of -1.2 V (vs. SCE) for 2 min to remove the initial oxide film formed on the sample surface due to air exposure. Subsequently, the sample was held in the solution for 30 min to obtain a stable open circuit potential (OCP). Finally, polarization was performed from -0.5 V (vs. SCE) to above the potential where stable pitting corrosion occurs, at a scan rate of 1 mV / s. To minimize experimental random error, the above potentiodynamic polarization test was repeated at least five times. Example 2

[0040] A laser additive manufacturing method for high-boron austenitic stainless steel powder, wherein the high-boron austenitic stainless steel powder is prepared by gas atomization into a combination of multiple components, and the mass percentage of its chemical composition is as follows:

[0041] C: 0.03%, Si: 0.5%, Cr: 19.5%, Ni: 14.21%, Mn: 2.89%, B: 1.28%, N: 0.006%, O: 0.01%, S: 0.01%, P: 0.01%, Fe is the balance.

[0042] The high-boron austenitic stainless steel powder has an average particle size of 15~53μm, a flowability of 22.0s / 50g, and a loose packing density of 5.05g / cm³. 3 The tap density is 4.68 g / cm³. 3 .

[0043] The preparation steps of high-boron austenitic stainless steel powder for laser additive manufacturing are as follows:

[0044] (1) Making bar stock: The high boron austenitic stainless steel is precisely batched according to the target composition of the high boron austenitic stainless steel, and then vacuum induction melting, electrode casting, forging and machining are carried out in sequence to obtain high boron austenitic stainless steel bar stock with a diameter of 60mm; the process parameters of vacuum induction melting, electrode casting, forging and machining are not specifically limited and can be selected according to the actual situation;

[0045] (2) Gas atomization powder production: The obtained high-boron austenitic stainless steel bar is fed into the feeding mechanism of the electrode induction melting inert gas atomization equipment, and gas atomization powder production is carried out under argon to obtain high-boron austenitic stainless steel powder. During gas atomization, the rotation speed of the high-boron austenitic stainless steel bar is 15 rpm; the atomizing gas pressure is 2.5 MPa, the atomizing gas feed rate is 0.8 mm / s; the nozzle structure of the gas atomization equipment is a confined nozzle;

[0046] (3) Powder post-treatment: The obtained high boron austenitic stainless steel powder is classified by a vibrating sieve to screen out powder with a particle size of 15~53μm. Then, the powder that meets the particle size requirements is placed in a low temperature vacuum drying equipment and dried for 3h.

[0047] Selective laser melting (SLM) was used to conduct forming experiments on high-boron austenitic stainless steel. The forming process parameters were set as follows: laser power 350W, scanning spacing 0.04mm, and scanning speed 150mm / s. Under these parameters, additive manufacturing was performed on block specimens with dimensions of 10mm×10mm×10mm and standard plate tensile specimens, such as... Figure 1 , 2 As shown. During the room temperature tensile property test, three measurements were performed and the average value was calculated. The pitting potential was determined by potentiodynamic polarization, with an electrode area of ​​0.25 cm². 2 The test used a 3.5 wt.% NaCl solution without deoxygenation, and polarized at a constant potential of -1.2 V (vs. SCE) for 2 min to remove the initial oxide film formed on the sample surface due to air exposure. Subsequently, the sample was held in the solution for 30 min to obtain a stable open circuit potential (OCP). Finally, polarization was performed from -0.5 V (vs. SCE) to above the potential where stable pitting corrosion occurs, at a scan rate of 1 mV / s. To minimize experimental random error, the above potentiodynamic polarization test was repeated at least five times. Example 3

[0048] A laser additive manufacturing method for high-boron austenitic stainless steel powder, wherein the high-boron austenitic stainless steel powder is prepared by gas atomization into a combination of multiple components, and the mass percentage of its chemical composition is as follows:

[0049] C: 0.026%, Si: 0.57%, Cr: 21.96%, Ni: 14.37%, Mn: 1.29%, B: 1.55%, N: 0.005%, O: 0.01%, S: 0.01%, P: 0.01%, Fe is the balance.

[0050] The high-boron austenitic stainless steel powder has an average particle size of 15~53μm, a flowability of 24.5s / 50g, and a loose packing density of 4.36g / cm³. 3 The tap density is 5.51 g / cm³. 3 .

[0051] The preparation steps of high-boron austenitic stainless steel powder for laser additive manufacturing are as follows:

[0052] (1) Making bar stock: The high boron austenitic stainless steel is precisely batched according to the target composition of the high boron austenitic stainless steel, and then vacuum induction melting, electrode casting, forging and machining are carried out in sequence to obtain high boron austenitic stainless steel bar stock with a diameter of 65mm; the process parameters of vacuum induction melting, electrode casting, forging and machining are not specifically limited and can be selected according to the actual situation;

[0053] (2) Gas atomization powder production: The obtained high-boron austenitic stainless steel bar is fed into the feeding mechanism of the electrode induction melting inert gas atomization equipment, and gas atomization powder production is carried out under argon to obtain high-boron austenitic stainless steel powder. The rotation speed of the high-boron austenitic stainless steel bar is 10 rpm; the atomizing gas pressure is 4 MPa, the atomizing gas feed rate is 1.0 mm / s; the nozzle structure of the gas atomization equipment is a confined nozzle;

[0054] (3) Powder post-treatment: The obtained high boron austenitic stainless steel powder is classified by a vibrating screener to screen out powder with a particle size of 15~53μm. Then, the powder that meets the particle size requirements is placed in a low temperature vacuum drying equipment and dried for 2h.

[0055] Selective laser melting (SLM) was used to conduct forming experiments on high-boron austenitic stainless steel. The forming process parameters were set as follows: laser power 220W, scanning spacing 0.04mm, and scanning speed 120mm / s. Under these parameters, additive manufacturing was performed on block specimens with dimensions of 10mm×10mm×10mm and standard plate tensile specimens, such as... Figure 1 , 2 As shown. During the room temperature tensile property test, three measurements were performed and the average value was calculated. The pitting potential was determined by potentiodynamic polarization, with an electrode area of ​​0.25 cm². 2 The test used a 3.5 wt.% NaCl solution without deoxygenation, and polarized at a constant potential of -1.2 V (vs. SCE) for 2 min to remove the initial oxide film formed on the sample surface due to air exposure. Subsequently, the sample was held in the solution for 30 min to obtain a stable open circuit potential (OCP). Finally, polarization was performed from -0.5 V (vs. SCE) to above the potential where stable pitting corrosion occurs, at a scan rate of 1 mV / s. To minimize experimental random error, the above potentiodynamic polarization test was repeated at least five times.

[0056] The tensile properties and breakdown potential in the potentiodynamic polarization curves of the high-boron austenitic stainless steels prepared in the above three embodiments are shown in Table 1.

[0057] High-boron austenitic stainless steels prepared using conventional casting-hot deformation and powder metallurgy processes of 304B4 were used as Comparative Examples 1 and 2, with a boron content of 1.14%. The tensile properties and breakdown potentials of Comparative Examples 1 and 2 are shown in Table 1. Table 1

[0058]

[0059] The high-boron austenitic stainless steel powder of this invention exhibits excellent process stability and formability when used in laser additive manufacturing via selective laser melting (SLM). Under non-heat-treated conditions in the packed state, the prepared samples show a tensile strength exceeding 950 MPa and an elongation after fracture of not less than 14%, while also possessing good pitting corrosion resistance. In contrast, 304B4 high-boron steel components prepared using traditional casting-hot deformation or powder metallurgy processes exhibit significant inherent defects: during solidification or sintering, they readily form a large number of coarse-sized, high-hardness, and low-melting-point eutectic borides. The presence of these brittle phases not only severely reduces the material's strength and plastic deformation capacity but also induces significant chromium-depleted zones around them, thereby impairing pitting corrosion resistance.

[0060] The high-boron austenitic stainless steel powder for laser additive manufacturing of this invention is suitable for the forming of complex components and integral parts in fields such as spent fuel processing and transport container manufacturing.

Claims

1. A high-boron austenitic stainless steel powder for laser additive manufacturing, characterized in that: It consists of the following components by mass percentage: C: ≤0.04%, Si: 0.3-1.0%, Cr: 19-22%, Ni: 11-15%, Mn: 1.2-3.0%, B: 0.8-1.6%, N≤0.01%, O≤0.04%, S≤0.02%, P≤0.02%, and Fe as the balance.

2. The high-boron austenitic stainless steel powder for laser additive manufacturing according to claim 1, characterized in that: The powder has an average particle size of 15-53 μm, a flowability of 20-28 s / 50 g, and a bulk density of 4.1-5.8 g / cm³. 3 The tap density is 4.5~6.0 g / cm³. 3 .

3. A method for preparing high-boron austenitic stainless steel powder for laser additive manufacturing as described in claim 1 or 2, characterized in that... The steps are as follows: 1) Making bar stock: The high boron austenitic stainless steel is prepared by batching according to the composition of the high boron austenitic stainless steel, and then vacuum induction melting, electrode casting, forging and machining are carried out in sequence to prepare high boron austenitic stainless steel bars. 2) Gas atomization powder making: The prepared high boron austenitic stainless steel bar is fed into the feeding mechanism of the electrode induction melting inert gas atomization equipment for gas atomization powder making to obtain high boron austenitic stainless steel powder. 3) Powder post-treatment: The obtained high-boron austenitic stainless steel powder is classified and dried.

4. The preparation method according to claim 3, characterized in that: In step 1), the diameter of the high-boron austenitic stainless steel bar is 50~70mm.

5. The preparation method according to claim 3, characterized in that: In step 2), during gas atomization, the rotation speed of the high-boron austenitic stainless steel bar is 5~25 rpm.

6. The preparation method according to claim 3, characterized in that: In step 2), the inert gas used for atomization is argon.

7. The preparation method according to claim 3, characterized in that: In step 2), the nozzle structure of the atomizing device is a restricted nozzle.

8. The preparation method according to claim 3, characterized in that: In step 2), the pressure of the atomizing gas is 2~5MPa and the feed rate of the atomizing gas is 0.5~1.2mm / s.

9. The preparation method according to claim 3, characterized in that: In step 3), the powder is classified using a vibrating sieve to screen out powder with a particle size of 15~53μm; the powder that meets the particle size requirements is dried for 3~5 hours.

Images