A high-nitrogen non-magnetic austenitic steel, a preparation method and application thereof

Abstract

This invention relates to the field of additive manufacturing technology for metallic materials, specifically to a high-nitrogen non-magnetic austenitic steel, its preparation method, and its applications. Its chemical composition, by mass fraction, is: Cr: 15.5-24.5%, Mn: 12.5-19.5%, C: 0.25-0.35%, N: 0.25-0.45%, O: 0.01-0.08%, with the balance being Fe and unavoidable impurities, totaling 100%. Using laser powder bed melting (LPBF) additive manufacturing, by optimizing laser process parameters, a completely non-magnetic high-nitrogen non-magnetic austenitic steel is obtained. This fundamentally solves the electromagnetic interference problem of traditional high-strength steel on battery management systems. Simultaneously, it possesses excellent strength-plasticity matching, corrosion resistance, and the ability to form complex structures in an integrated manner, making it particularly suitable for manufacturing battery pack shells for new energy vehicles.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology for metallic materials, specifically to a high-nitrogen non-magnetic austenitic steel, its preparation method, and its applications. Background Technology

[0002] In the new energy vehicle industry, pure electric vehicles have become the market mainstream. As the core energy storage unit of the entire vehicle, the safety, reliability, and lightweighting of the battery pack directly affect the overall vehicle performance. The battery pack casing, as the main load-bearing and protective structure of the battery system, must withstand complex loads such as vibration, impact, and compression during service, while ensuring the integrity of the battery modules under extreme conditions (such as collisions and fires). Furthermore, with the increasing sophistication of battery management systems (BMS) and onboard electronic equipment, electromagnetic compatibility (EMC) of materials has become a key indicator in battery pack casing design.

[0003] Currently, there are two main technical routes for battery pack casing materials: Aluminum alloy route: Although aluminum alloys can achieve significant weight reduction, their strength and plasticity are poorly matched, and they are prone to plastic instability or fracture under extreme collision scenarios; their high temperature resistance is insufficient, and they are prone to melt-through failure under fire conditions such as thermal runaway; in addition, primary aluminum production has high energy consumption and large carbon emissions throughout its life cycle, which does not conform to the trend of green and low-carbon development.

[0004] High-strength steel approach: Advanced high-strength steels, represented by DP1180, have comprehensive advantages in terms of cost, impact resistance, fire resistance, and carbon emissions throughout their life cycle. However, these dual-phase steels are ferromagnetic, with a relative permeability typically much higher than 1, which may cause electromagnetic interference to BMS sensors, current sensors, and wireless communication equipment inside the battery pack, affecting signal transmission accuracy. Simultaneously, the poor strength-plasticity match and insufficient plasticity reserve of dual-phase steel limit its application in complex shaped structures.

[0005] In recent years, laser powder bed melting (LPBF) has emerged as one of the mainstream technologies in metal additive manufacturing, enabling near-net-shape forming of complex metal components and providing a new manufacturing approach for structural innovations in battery pack casings (such as integrated cooling channels and biomimetic energy-absorbing structures). However, applying LPBF technology to battery pack casing manufacturing faces material bottlenecks: most high-strength steels (such as martensitic steel and duplex steel) readily form magnetic phases like martensite under the rapid solidification conditions of LPBF, failing to meet the non-magnetic requirement; while traditional austenitic stainless steels (such as 304 and 316L), although non-magnetic, typically have a strength below 200 MPa, far from meeting the high strength and high intrusion resistance requirements of battery pack casings. Summary of the Invention

[0006] To address the shortcomings of the existing technologies, the purpose of this invention is to provide a high-nitrogen non-magnetic austenitic steel, its preparation method, and its applications. This invention aims to develop a novel steel material that combines complete non-magnetism, high strength, high plasticity, excellent corrosion resistance, and compatibility with the rapid solidification characteristics of LPBF. This addresses the problems of low strength and poor high-temperature resistance in existing aluminum alloys, as well as the magnetic interference and insufficient plasticity of existing high-strength steels. This is of great significance for improving the safety, reliability, and overall performance of new energy vehicle battery packs.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A high-nitrogen non-magnetic austenitic steel, wherein the chemical composition of the high-nitrogen non-magnetic austenitic steel by mass fraction is: Cr: 15.5-24.5%, Mn: 12.5-19.5%, C: 0.25-0.35%, N: 0.25-0.45%, O: 0.01-0.08%, with the balance being Fe and unavoidable impurities, totaling 100%.

[0008] In a preferred embodiment of the present invention, the chemical composition of the high-nitrogen non-magnetic austenitic steel by mass fraction is: Cr: 15.78%, Mn: 15.13%, C: 0.26%, N: 0.34%, O: 0.059%, with the balance being Fe and unavoidable impurities, totaling 100%.

[0009] The method for preparing high-nitrogen non-magnetic austenitic steel is characterized by comprising the following steps: Weigh out each component of the powder according to the specified proportions, mix them under inert gas protection, and dry them to remove moisture and impurities, ensuring stability in subsequent processing.

[0010] The 3D model is sliced, laser process parameters are set, and powder is melted layer by layer under inert gas protection to form components.

[0011] After printing, the material is cooled to room temperature to obtain high-nitrogen non-magnetic austenitic steel.

[0012] In a preferred embodiment of the present invention, the laser process parameters are: laser power 200W-320W, scanning speed 500mm / s-1100mm / s, scanning spacing 70μm-90μm, and powder layer thickness 40μm-60μm.

[0013] In a preferred embodiment of the present invention, the inert gas is argon with a purity of not less than 99.99%.

[0014] In a preferred embodiment of the present invention, the particle size of each component powder is 15μm-53μm and the purity is not less than 99.9%.

[0015] In a preferred embodiment of the present invention, the drying temperature is 60℃-120℃ and the drying time is 2h-8h.

[0016] The application of the high-nitrogen non-magnetic austenitic steel described in this invention in the preparation of battery pack housings for new energy vehicles.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. The high-nitrogen non-magnetic austenitic steel of this invention has a fully austenitic structure, completely eliminating electromagnetic interference; it combines high strength and high plasticity, meeting the requirements of battery pack shells in terms of impact and energy absorption. The chemical composition of the high-nitrogen non-magnetic austenitic steel by mass fraction is: Cr: 15.5-24.5%, Mn: 12.5-19.5%, C: 0.25-0.35%, N: 0.25-0.45%, O: 0.01-0.08%, with the balance being Fe and unavoidable impurities, totaling 100%. Among them, Cr provides the matrix with corrosion resistance; Mn strongly stabilizes the austenitic phase, ensuring that the material maintains a non-magnetic fully austenitic structure during rapid cooling of LPBF and subsequent use; C and N, as interstitial atoms, play a strong solid solution strengthening role and are key elements for improving the strength of the material. Their content needs to be precisely controlled. Too low a content will result in insufficient strength, while too high a content may affect plasticity or form harmful carbonitrides.

[0018] 2. The high-nitrogen non-magnetic austenitic steel described in this invention fundamentally solves the potential interference problem of steel battery packs to precision electronic systems such as BMS in vehicles, ensuring the stable operation of the electronic control system of new energy vehicles and solving the core defect of magnetic interference of DP1180 steel; the high strength and high plasticity have good matching properties, which can meet the protection requirements of battery packs under extreme working conditions such as impact and extrusion, so that the battery pack shell can resist intrusion and effectively absorb energy in the collision, improving safety redundancy; LPBF technology can realize the molding of complex structures without complex molds, shorten the manufacturing cycle of battery pack shells, and adapt to the personalized design requirements of battery packs of different models; through precision molding and material performance advantages, lightweight design can be achieved while ensuring strength, so that the steel battery pack can reach a weight similar to that of aluminum battery packs, taking into account both safety and range improvement requirements.

[0019] 3. The high-nitrogen non-magnetic austenitic steel and its preparation method described in this invention are green, low-carbon, and cost-controllable. Based on an iron-based system, the raw materials are readily available and the cost is lower than that of aluminum alloys and some special alloys. The LPBF technology achieves near-net-shape forming, resulting in high material utilization, reduced waste, and lower scrap rate. The carbon emissions throughout the entire life cycle are low, which is in line with the trend of green and low-carbon development. Attached Figure Description

[0020] Figure 1 This is a flowchart of the LPBF process in Embodiment 1 of the present invention.

[0021] Figure 2 This is a schematic diagram of the tensile specimen in Example 1.

[0022] Figure 3 The images shown are SEM images of the metallographic structure in Example 1, where a is a SEM image of the metallographic structure at 20 μm and b is a SEM image of the metallographic structure at 10 μm. Detailed Implementation

[0023] The following detailed description, in conjunction with embodiments of the present invention and accompanying drawings, provides a clear and complete illustration of the technical solutions in these embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that all technical terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0025] A high-nitrogen non-magnetic austenitic steel, wherein the chemical composition of the high-nitrogen non-magnetic austenitic steel by mass fraction is: Cr: 15.5-24.5%, Mn: 12.5-19.5%, C: 0.25-0.35%, N: 0.25-0.45%, O: 0.01-0.08%, with the balance being Fe and unavoidable impurities, totaling 100%.

[0026] In a preferred embodiment of the present invention, the chemical composition of the high-nitrogen non-magnetic austenitic steel by mass fraction is: Cr: 15.78%, Mn: 15.13%, C: 0.26%, N: 0.34%, O: 0.059%, with the balance being Fe and unavoidable impurities, totaling 100%.

[0027] The method for preparing high-nitrogen non-magnetic austenitic steel is characterized by comprising the following steps: Weigh out each component of the powder according to the specified proportions, mix them under inert gas protection, and dry them to remove moisture and impurities, ensuring stability in subsequent processing.

[0028] The 3D model is sliced, laser process parameters are set, and powder is melted layer by layer under inert gas protection to form components.

[0029] After printing, the material is cooled to room temperature to obtain high-nitrogen non-magnetic austenitic steel.

[0030] In a preferred embodiment of the present invention, the laser process parameters are: laser power 200W-320W, scanning speed 500mm / s-1100mm / s, scanning spacing 70μm-90μm, and powder layer thickness 40μm-60μm.

[0031] In a preferred embodiment of the present invention, the inert gas is argon with a purity of not less than 99.99%.

[0032] In a preferred embodiment of the present invention, the particle size of each component powder is 15μm-53μm and the purity is not less than 99.9%.

[0033] In a preferred embodiment of the present invention, the drying temperature is 60℃-120℃ and the drying time is 2h-8h.

[0034] Example 1 (1) Weigh the powder precisely according to the mass percentages of Cr: 15.8%, Mn: 15.1%, C: 0.26%, N: 0.34%, O: 0.059%, with the balance being Fe. Place the weighed powder in a vacuum drying oven and dry it at 80°C for 4 hours.

[0035] (2) A laser powder bed melting device was used. Before the device was put into operation, the focusing of the optical path, the flatness of the powder spreading roller, and the sealing of the argon protective gas path were checked. The laser power was set to 200W, the scanning speed to 900mm / s, the scanning interval to 80μm, the layer thickness to 50μm, and argon gas with a purity of 99.99% was introduced.

[0036] (3) A layer of alloy powder is pre-spread on the molding substrate. According to the three-dimensional model of the rectangular part designed, the equipment melts and stacks the powder layer by layer. During the manufacturing process, the laser energy feedback and the powder melting state are monitored in real time.

[0037] (4) After printing, allow the molded part to cool naturally to room temperature on the printing bed, and then remove it from the substrate.

[0038] (5) The mechanical properties of the sample were tested. The tensile sample was processed and polished for room temperature tensile testing. The tensile test showed a yield strength of 908 MPa, a tensile strength of 1177 MPa, and an elongation after fracture of 34%, which showed excellent mechanical properties.

[0039] Example 2 (1) Weigh the powder precisely according to the mass percentages of Cr: 15.8%, Mn: 15.1%, C: 0.26%, N: 0.34%, O: 0.059%, with the balance being Fe. Place the weighed powder in a vacuum drying oven and dry it at 80°C for 4 hours.

[0040] (2) A laser powder bed melting device was used. Before the device was put into operation, the focusing of the optical path, the flatness of the powder spreading roller, and the sealing of the argon protective gas path were checked. The laser power was set to 240W, the scanning speed to 1100mm / s, the scanning interval to 80μm, the layer thickness to 50μm, and argon gas with a purity of 99.99% was introduced.

[0041] (3) A layer of alloy powder is pre-spread on the molding substrate. According to the three-dimensional model of the rectangular part designed, the equipment melts and stacks the powder layer by layer. During the manufacturing process, the laser energy feedback and the powder melting state are monitored in real time.

[0042] (4) After printing, allow the molded part to cool naturally to room temperature on the printing bed, and then remove it from the substrate.

[0043] (5) The mechanical properties of the sample were tested. The tensile sample was processed and polished for room temperature tensile testing. The tensile test showed a yield strength of 936 MPa, a tensile strength of 1193 MPa, and an elongation after fracture of 32%, which showed excellent mechanical properties.

[0044] Comparative Example 1: Traditional preparation methods and properties of DP1180 high-strength steel: (1) DP1180 steel was smelted in an electric arc furnace and then cast into slabs by a continuous casting machine after refining. (2) The slab is sent into the heating furnace and heated to 1200℃. After holding for 2 hours, it is hot rolled. The final rolling temperature is controlled at 850℃. After being rolled into a hot rolled coil, it is coiled at 600℃. (3) Pickling is performed on the hot-rolled coil to remove the oxide scale, followed by cold rolling, with the reduction rate controlled at 40%, to obtain the cold-rolled plate of the target thickness; (4) The cold-rolled sheet is fed into a continuous annealing furnace and held at 800℃ for 3 minutes. Then it is air-cooled to room temperature to complete the formation of the dual-phase structure (ferrite + martensite) and obtain the finished DP1180 dual-phase steel. (5) Tensile samples were processed according to the same standards as in Examples 1 and 2, and room temperature mechanical property tests were conducted. The mechanical properties of the finished DP1180 duplex steel were a yield strength of 700 MPa, a tensile strength of 1280 MPa, and an elongation after fracture of 8%, with poor plasticity. These results refer to the research on the traditional preparation process and microstructure of cold-rolled DP1180 duplex steel by the Yanshan University team.

[0045] Comparative Example 2: Laser additive manufacturing with traditional high C+N composition (1) Weigh the powder precisely according to the following mass percentages: Cr: 18.8%, Mn: 18.9%, C: 0.489%, N: 0.578%, O: 0.293%, with the balance being Fe. Mix the powder using a three-dimensional powder mixer at 80 r / min for 120 min to ensure uniform mixing. Place the mixed powder in a vacuum drying oven and dry it at 80℃ for 4 hours.

[0046] (2) A laser powder bed melting device was used. Before the device was put into operation, the focusing of the optical path, the flatness of the powder spreading roller, and the sealing of the argon protective gas path were checked. The laser power was set to 200W, the scanning speed to 900mm / s, the scanning interval to 80μm, the layer thickness to 50μm, and argon gas with a purity of 99.99% was introduced.

[0047] (3) A layer of alloy powder is pre-spread on the molding substrate. According to the three-dimensional model of the cube part designed, the equipment melts and stacks the powder layer by layer. During the manufacturing process, the laser energy feedback and the powder melting state are monitored in real time.

[0048] (4) After printing, allow the molded part to cool naturally to room temperature on the printing bed, and then remove it from the substrate.

[0049] (5) The mechanical properties of the samples were tested. The tensile samples were processed and polished for room temperature tensile testing. The tensile test showed a yield strength of 626 MPa, a tensile strength of 887 MPa, and an elongation after fracture of 15%, which are far lower than those of the present invention. This result is based on the research of Sun Xin and Zhao Dingguo's team at North China University of Technology.

[0050] Results Analysis Figure 1 This is a flow chart of the LPBF process in Embodiment 1 of the present invention. The LPBF process begins with the preparation of raw material powder, using pre-alloyed powder with a particle size of 15μm-53μm and a purity of ≥99.9%. After thorough drying, moisture is completely removed to avoid printing defects. Subsequently, near-net-shape forming is achieved through 3D model design and slicing, followed by the core laser layer-by-layer melting and powder laying stage. Optimized process parameters (power 200W-320W, scanning speed 500mm / s-1100mm / s, scanning spacing 70-90μm, powder layer thickness 40μm-60μm) are used to ensure that the formed part is crack-free and has high density. Finally, the part is cooled to room temperature and removed, completing the preparation. This process design is optimized for the characteristics of high-nitrogen austenitic steel. By adjusting the parameters, it solves the problems of easy oxidation and cracking in traditional processes, while improving the uniformity of the microstructure and the stability of the performance.

[0051] From particle size control to laser parameter optimization, precise regulation of austenite grain size, phase composition, and defect density was achieved. In Example 1, the synergistic effect of the austenite structure and the highly dissolved C and N elements enabled the material to achieve a tensile strength of 1170 MPa while maintaining a fracture elongation of 35%, breaking through the bottleneck of the traditional material's "strength-plasticity inversion".

[0052] Figure 2 This is a schematic diagram of the tensile specimen in Example 1. As can be seen from the figure, the sample in Example 1 is a tensile specimen with a length of 28 mm and a width of 6.5 mm.

[0053] Comparing the mechanical properties of Example 1 and Comparative Example 1, it can be seen that Example 1 (FeCrMnCN) has no obvious yield plateau, exhibits continuous yielding behavior, a long work hardening stage, and necking occurs in the high strain region (>30%), maintaining a high stress level before fracture. LPBF rapidly solidifies to form a fine-grained austenitic structure, with solid solution strengthening by C and N elements. Simultaneously, the austenitic phase has high stability and high plasticity. In contrast, Comparative Example 1 (DP1180) has an obvious yield plateau, limited work hardening ability, early necking (strain <8%), and low fracture elongation.

[0054] Figure 3 The image shown is a scanned metallographic SEM image from Example 1. Figure 3 Images a and b clearly demonstrate the material's microstructure. This structure is a single, uniform, fine-grained austenitic structure, free of magnetic phases such as ferrite and martensite, as well as carbonitride precipitates. The grain boundaries are clear and free of obvious cracks, pores, or other printing defects. The grain size is refined to the micro-nano scale due to the rapid solidification effect of LPBF, which is the core microscopic basis for the material's completely non-magnetic properties. Simultaneously, C and N interstitial atoms are uniformly dissolved in the austenitic lattice without grain boundary segregation. This microstructure allows the material to possess both solid solution strengthening and fine-grain strengthening effects, which is also the key reason for its yield strength exceeding 900 MPa and elongation after fracture reaching 34%, achieving a good balance between strength and plasticity. Compared to the coarse ferrite-martensite structure of traditional DP1180 dual-phase steel and the grain boundary precipitation and compositional segregation problems of high C+N contrast samples, the defect-free and single-phase uniform microstructure of this material not only solves the magnetic interference problem but also breaks through the bottleneck of the traditional material strength-plasticity inversion. This fully demonstrates the rationality of the alloy composition design and LPBF process parameter optimization of this patent, providing a reliable microstructure guarantee for the application of the material in the battery pack shell of new energy vehicles.

[0055] Therefore, traditional casting processes result in coarse grains and uneven microstructure. The ferrite-martensite dual-phase structure necks under low strain, limiting its plasticity.

[0056] Laser-assisted powder bed melting (LPBF) is one of the mainstream technologies in metal additive manufacturing. It uses a high-energy laser beam to selectively melt metal powder layer by layer along a 3D model slicing path, directly producing dense, near-net-shape metal parts. This technology is particularly suitable for the production of complex structures, small batches, or customized parts.

[0057] Microstructure and Performance Mechanism of High-Nitrogen Non-Magnetic Austenitic Steel: Austenitic stainless steel is typically non-magnetic but has low strength. In the high-nitrogen non-magnetic austenitic steel designed in this invention, Cr and Mn are austenite stabilizing elements, while C and N further promote austenite formation. Precise proportioning ensures that the material forms a single austenitic microstructure after forming and post-treatment. The austenitic microstructure itself is non-magnetic, thus achieving non-magnetic properties and avoiding interference with battery communication. Simultaneously, C and N atoms dissolved in the austenite lattice form solid solution strengthening, which, combined with the grain refinement effect brought about by rapid solidification using LPBF technology and the stress elimination effect of post-treatment, gives the material both high strength and high ductility.

[0058] Performance requirements for battery pack casings in new energy vehicles: In addition to basic mechanical strength and rigidity, the electromagnetic compatibility (EMC) requirements for materials are becoming increasingly stringent to prevent interference with low-voltage electrical systems, BMS signals, and wireless charging. Non-magnetic properties are an important attribute for meeting these requirements; the Fe of this invention... 68.5 Cr 15.8 Mn 15.1 C 0.26 N 0.34 The steel and its preparation method can fully meet this requirement.

[0059] Compared to traditional DP1180 steel, the high-nitrogen non-magnetic austenitic steel of this invention maintains similar high strength while increasing plasticity by more than four times, and fundamentally eliminates magnetism. Furthermore, the LPBF process used in this invention enables integrated forming of complex structures. Compared to the multiple traditional processes such as stamping and welding required for DP1180 steel plates, it offers potential advantages such as high design freedom and simplified processes when manufacturing complex shell components. Compared to traditional high-C+N composition steels, the high Cr and Mn content and total C+N content (exceeding 1%) during printing easily lead to solidification cracks and porosity, resulting in grain boundary carbonitride precipitation and compositional segregation. Therefore, its tensile properties are significantly inferior to the alloy of this invention.

[0060] By using a specific high-nitrogen non-magnetic austenitic steel alloy composition design and LPBF additive manufacturing, the following significant effects can be achieved: 1. Completely eliminate electromagnetic interference: The material has a single austenitic structure, which fundamentally solves the potential interference problem of steel battery packs to BMS and other precision electronic systems in vehicles, ensuring the stable operation of the electronic control system of new energy vehicles and solving the core defect of magnetic interference of DP1180 steel.

[0061] 2. Excellent mechanical properties: The combination of high strength and high plasticity can meet the protection requirements of battery packs under extreme conditions such as impact and compression, so that the battery pack shell can resist intrusion and effectively absorb energy in the collision, thus improving safety redundancy.

[0062] 3. Strong process adaptability: LPBF technology can achieve complex structure molding without complex molds, shorten the battery pack shell manufacturing cycle, and adapt to the personalized design requirements of battery packs for different vehicle models.

[0063] 4. Adapting to lightweight requirements: Through precision molding and material performance advantages, lightweight design can be achieved while ensuring strength, making the steel battery pack weigh similarly to the aluminum battery pack, thus balancing the needs for safety and improved range.

[0064] 5. Green, low-carbon and cost-controllable: Based on the iron-based system, raw materials are readily available and the cost is lower than that of aluminum alloys and some special alloys; LPBF technology achieves near-net-shape forming, with high material utilization, reduced waste, and lower scrap rate; low carbon emissions throughout the entire life cycle, which is in line with the trend of green and low-carbon development.

[0065] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

[0066] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A high-nitrogen non-magnetic austenitic steel, characterized in that, The chemical composition of the high-nitrogen non-magnetic austenitic steel, by mass fraction, is as follows: Cr: 15.5%-24.5%, Mn: 12.5%-19.5%, C: 0.25%-0.35%, N: 0.25%-0.45%, O: 0.01%-0.08%, with the balance being Fe and unavoidable impurities, totaling 100%.

2. The high-nitrogen non-magnetic austenitic steel according to claim 1, characterized in that, The chemical composition of the high-nitrogen non-magnetic austenitic steel, by mass fraction, is: Cr: 15.78%, Mn: 15.13%, C: 0.26%, N: 0.34%, O: 0.059%, with the balance being Fe and unavoidable impurities, totaling 100%.

3. The method for preparing high-nitrogen non-magnetic austenitic steel according to claim 1, characterized in that, Includes the following steps: Weigh the pre-alloyed powder according to the proportion, mix it under inert gas protection, and dry it to remove moisture and impurities from the powder. The three-dimensional model is sliced, laser process parameters are set, and powder is melted layer by layer under inert gas protection to form components; After printing, the material is cooled to room temperature to obtain high-nitrogen non-magnetic austenitic steel.

4. The method for preparing high-nitrogen non-magnetic austenitic steel according to claim 3, characterized in that, The laser process parameters are: laser power 200W-320W, scanning speed 500mm / s-1100mm / s, scanning spacing 70μm-90μm, and powder layer thickness 40μm-60μm.

5. The method for preparing high-nitrogen non-magnetic austenitic steel according to claim 3, characterized in that, The inert gas is argon with a purity of not less than 99.99%.

6. The method for preparing high-nitrogen non-magnetic austenitic steel according to claim 3, characterized in that, The particle size of each component powder is 15μm-53μm, and the purity is not less than 99.9%.

7. The method for preparing high-nitrogen non-magnetic austenitic steel according to claim 3, characterized in that, The drying temperature is 60℃-120℃, and the drying time is 2h-8h.

8. The application of the high-nitrogen non-magnetic austenitic steel according to claim 1 in the preparation of battery pack housings for new energy vehicles.

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