Non-magnetic stainless steel as well as preparation process and application thereof

Abstract

The invention relates to the field of stainless steel, and discloses non-magnetic stainless steel and a preparation process and application thereof. The non-magnetic stainless steel is prepared from the following raw materials in percentage by weight: 16 to 16.5 percent of chromium, 11 to 12 percent of manganese, 5.9 to 6.4 percent of nickel, 0.1 to 0.3 percent of copper, 0.12 to 0.22 percent of cobalt, 0.1 to 0.2 percent of vanadium, 0.1 to 0.2 percent of molybdenum, 0.05 to 0.1 percent of carbon, 0.2 to 0.4 percent of titanium, 0.2 to 0.5 percent of silicon, less than or equal to 0.04 percent of phosphorus, less than or equal to 0.01 percent of sulfur, 0.04 to 0.09 percent of niobium, 0.02 to 0.06 percent of tungsten, 0.008 to 0.018 percent of aluminum, 0.03 to 0.09 percent of nitrogen, 0.003 to 0.008 percent of tin, 0.002 to 0.005 percent of boron and the balance of iron and inevitable impurities. The material has the advantages of high strength and hardness, high ductility and corrosion resistance, low and stable magnetic permeability of a stretched product, and suitability for the fields of sensors and the like.

Description

Technical Field

[0001] This application relates to the field of stainless steel materials, and more specifically, to a non-magnetic stainless steel, its preparation process, and its applications. Background Technology

[0002] Austenitic stainless steel is a type of stainless steel that exhibits an austenitic structure at room temperature, with a face-centered cubic crystal structure. This austenitic structure is typically formed by adding chromium and nickel. The austenitic structure endows austenitic stainless steel with a range of excellent properties, such as non-magnetism, high toughness, and good corrosion resistance. Therefore, austenitic stainless steel is widely used in numerous fields, including medical, electronics, aerospace, shipbuilding, and petrochemical industries.

[0003] Among various austenitic stainless steels, SUS304 and SUS305 are two common types. SUS304 stainless steel typically has a chromium content of 18-20% and a nickel content of 8-10.5%, while SUS305 stainless steel has a chromium content of 17-19% and a nickel content of 10.5-13%. Due to the higher nickel content, austenitic stainless steel retains its martensitic state largely after processing, thus exhibiting good non-magnetic properties, and the higher nickel content also contributes to its good toughness. However, nickel is a relatively scarce metal resource in my country, with limited domestic reserves. Using a high nickel content in the production of austenitic stainless steel easily leads to resource waste and significantly increases production costs, hindering the large-scale industrial production of austenitic stainless steel.

[0004] Existing technologies also include some low-nickel austenitic stainless steels, with nickel content reduced to between 2-4.5%. These are achieved by incorporating larger amounts of elements such as copper, nitrogen, molybdenum, and manganese to improve the strength and toughness of the austenitic stainless steel. While this type of austenitic stainless steel possesses good strength and hardness, the reduced nickel content brings several problems. On one hand, the toughness, elongation, and corrosion resistance of the austenitic stainless steel decrease significantly. During stretching, the product is prone to localized deformation or cracking, and its corrosion resistance is weakened. On the other hand, after stretching, the magnetic permeability of the austenitic stainless steel increases, affecting its magnetic properties. This low-nickel austenitic stainless steel can meet the requirements for everyday food utensils, water cups, and wearable accessories such as buttons and zippers. However, in applications requiring high dimensional accuracy, sensitivity, and stability, such as sensors and motor housings, the overall performance requirements for non-magnetic stainless steel are much higher. If the performance of non-magnetic stainless steel is unstable, it could potentially cause safety accidents, thus significantly reducing its applicability in these fields. Summary of the Invention

[0005] To address the challenge of balancing strength, hardness, ductility, corrosion resistance, and magnetic permeability when using existing low-nickel austenitic stainless steel in applications requiring high dimensional accuracy, sensitivity, and stability, this application provides a non-magnetic stainless steel, its preparation process, and its applications.

[0006] In the first aspect, this application provides a non-magnetic stainless steel, which adopts the following technical solution: A non-magnetic stainless steel is made from the following raw materials in weight percentages: chromium 16-16.5%, manganese 11-12%, nickel 5.9-6.4%, copper 0.1-0.3%, cobalt 0.12-0.22%, vanadium 0.1-0.2%, molybdenum 0.1-0.2%, carbon 0.05-0.1%, titanium 0.2-0.4%, silicon 0.2-0.5%, phosphorus ≤0.04%, sulfur ≤0.01%, niobium 0.04-0.09%, tungsten 0.02-0.06%, aluminum 0.008-0.018%, nitrogen 0.03-0.09%, tin 0.003-0.008%, boron 0.002-0.005%, with the balance being iron and unavoidable impurities.

[0007] By adopting the above technical solution, this application uses iron, chromium, manganese and nickel as the base components, and combines them with copper, cobalt, vanadium, molybdenum, carbon, titanium, silicon, phosphorus, sulfur, niobium, tungsten, aluminum, nitrogen, tin and boron to prepare a non-magnetic and rust-free steel with austenitic structure and low nickel content. It has high strength and hardness, as well as good ductility and corrosion resistance. The semi-finished product has low magnetic permeability, and it can still maintain low magnetic permeability after being stretched into a finished product.

[0008] Chromium, in particular, has good strength and hardness, which can improve the strength, hardness, corrosion resistance, and oxidation resistance of non-magnetic stainless steel.

[0009] Manganese, as a deoxidizer, can combine with sulfur to form high-melting-point substances, which to some extent eliminates the harmful effects of sulfur, thereby reducing the brittleness of non-magnetic stainless steel and increasing its strength and hardness.

[0010] Nickel can lower the brittle transition temperature of non-magnetic stainless steel, improve low-temperature toughness, improve processability and weldability, increase strength without significantly reducing toughness, and also improve corrosion resistance.

[0011] Copper, when combined with other elements, can further improve the strength of non-magnetic stainless steel while enhancing its toughness.

[0012] Cobalt can increase the Curie temperature of non-magnetic stainless steel, thereby increasing the high-temperature hardness of the matrix, reducing the solid solubility of molybdenum in the matrix, and promoting the precipitation of molybdenum-containing intermetallic compounds, thus improving the strength, hardness and oxidation resistance of non-magnetic stainless steel. The addition of cobalt can also enhance the formation of the metallic phase, thereby improving the high-temperature creep strength of non-magnetic stainless steel.

[0013] Vanadium significantly improves the heat resistance and oxidation resistance of non-magnetic stainless steel. At high temperatures, vanadium can prevent the oxidation of other alloying elements (such as molybdenum), thus extending the service life of non-magnetic stainless steel. Vanadium also enhances the corrosion resistance of non-magnetic stainless steel by forming a protective oxide film that prevents further corrosion. Furthermore, vanadium works synergistically with other alloying elements (such as chromium) to significantly improve the material's resistance to electrochemical corrosion.

[0014] A better ratio of molybdenum helps improve the strength and toughness of non-magnetic stainless steel. If the molybdenum content is too low, it will reduce the strength and toughness of non-magnetic stainless steel. If the molybdenum content is too high, it will reduce the magnetic stability of non-magnetic stainless steel.

[0015] Carbon can form carbides with other alloying elements, which can affect the strength and hardness of stainless steel to a certain extent. If the carbon content is too high, carbides will precipitate, affecting the magnetic stability of non-magnetic stainless steel. If the carbon content is too low, the formation of carbides will be reduced, thereby reducing the mechanical properties and corrosion resistance of non-magnetic stainless steel.

[0016] Titanium can refine the grains of non-magnetic stainless steel, reduce its tendency to overheat, improve its weldability, reduce the hot brittleness of sulfur, and enhance the strength and toughness of non-magnetic stainless steel.

[0017] Silicon is used as a deoxidizer in steelmaking. Silicon can react with iron oxide in molten steel to form silicate slag with low density, which can remove part of the slag. In non-magnetic stainless steel, silicon dissolves in ferrite, which increases the strength and hardness of the non-magnetic stainless steel, but reduces its plasticity and toughness. Therefore, the amount of silicon used needs to be controlled and cannot be too large.

[0018] Phosphorus can increase the hardness of steel, but it causes a significant decrease in plasticity and impact toughness. Therefore, the amount of phosphorus used should be controlled within 0.04%. Sulfur comes from steelmaking ore and fuel coke. Sulfur exists in non-magnetic stainless steel in the form of iron sulfide. Iron sulfide and iron form low-melting-point compounds, which will reduce the performance of non-magnetic stainless steel. Therefore, the amount of sulfur used should be controlled within 0.01%.

[0019] Niobium enhances the oxidation resistance and corrosion resistance of non-magnetic stainless steel by forming a protective oxide film, effectively preventing oxygen from further diffusing into the interior of the non-magnetic stainless steel, thereby improving the material's corrosion resistance. Niobium can also prevent the steel from overheating, reduce aging sensitivity, and improve weldability.

[0020] Tungsten can enhance the tempering stability of non-magnetic stainless steel. Tungsten can also dissolve in ferrite to form tungsten carbides. These properties make tungsten perform well at high temperatures and significantly improve the hot strength of steel.

[0021] Aluminum can further exhibit good synergistic effects with copper, cobalt, vanadium, tin, niobium, and tungsten, improving strength and hardness while enhancing ductility and corrosion resistance.

[0022] The reason why non-magnetic stainless steel can resist corrosion from the atmosphere, water, acids, alkalis, and other corrosive media is mainly due to the addition of a certain amount of chromium. The addition of nitrogen further enhances the corrosion resistance of non-magnetic stainless steel. After nitrogen combines with chromium and manganese, it can form a dense oxide film on the material surface, effectively preventing further erosion by corrosive media. In addition, nitrogen can significantly improve the strength and hardness of metallic materials through solid solution strengthening and grain refinement. However, if too much nitrogen is used, it will promote the precipitation of nitrides, affecting the magnetic permeability of non-magnetic stainless steel.

[0023] In non-magnetic stainless steel, even a small amount of boron can significantly refine the grains, thereby improving the strength and corrosion resistance of the stainless steel. Boron can also significantly improve the hardenability of non-magnetic stainless steel, making it easier to achieve the required hardness during quenching. The addition of a higher boron content can multiply the hardenability of non-magnetic stainless steel, thereby reducing the amount of elements such as nickel, chromium, and molybdenum. This results in non-magnetic stainless steel having good strength and hardness, as well as good ductility and corrosion resistance.

[0024] In summary, by optimizing the dosage of the aforementioned elements, the components exhibit a better synergistic effect. This allows the base components, such as chromium, manganese, and nickel, to be used in smaller quantities, while in combination with smaller amounts of copper, cobalt, vanadium, molybdenum, carbon, titanium, silicon, niobium, tungsten, aluminum, nitrogen, tin, and boron. The resulting non-magnetic stainless steel possesses excellent comprehensive performance and stability. This solves the problem of balancing strength, hardness, ductility, corrosion resistance, and magnetic permeability when existing low-nickel austenitic stainless steels are used in fields requiring high dimensional accuracy, high sensitivity, and high stability. It is suitable for applications requiring high dimensional accuracy, high sensitivity, and high stability, such as sensors (including those used in automotive water tanks, water temperature, oil temperature, parking, and braking systems), motor housings, communication base stations, signal shielding, vacuum magnetrons, and magnetic switches.

[0025] Preferably, the weight ratio of titanium to carbon is (3-5):1.

[0026] By employing the above technical solutions, the formation of titanium carbide can refine the grains of non-magnetic stainless steel and reduce its overheating tendency. A titanium-to-carbon ratio of 5:1 significantly refines the grains and improves the mechanical properties of the non-magnetic stainless steel; a ratio of 3:1 yields the highest creep resistance. Optimizing the titanium-to-carbon ratio prevents the precipitation of chromium carbide along austenite grain boundaries during heating, thus reducing creep deformation and improving the weldability of the stainless steel, reducing problems during welding. Furthermore, titanium can react with sulfur, reducing the hot brittleness caused by sulfur.

[0027] Preferably, it is made from the following raw materials in weight percentages: chromium 16.3-16.5%, manganese 11.4-11.6%, nickel 6-6.1%, copper 0.2-0.3%, cobalt 0.16-0.18%, vanadium 0.15-0.2%, molybdenum 0.12-0.15%, carbon 0.075-0.1%, titanium 0.3-0.375%, silicon 0.4-0.5%, phosphorus ≤0.04%, sulfur ≤0.01%, niobium 0.05-0.07%, tungsten 0.02-0.04%, aluminum 0.01-0.013%, nitrogen 0.03-0.06%, tin 0.003-0.005%, boron 0.002-0.004%, with the balance being iron and unavoidable impurities.

[0028] By adopting the above technical solution, the proportion of each component is further optimized so that the components work synergistically. While reducing the amount of each component, a non-magnetic stainless steel with good strength and hardness, as well as good ductility and corrosion resistance, is prepared. The obtained non-magnetic stainless steel has low magnetic permeability and good stability.

[0029] Preferably, when the thickness of the non-magnetic stainless steel is 0.1-0.6mm, the magnetic permeability of the non-magnetic stainless steel is ≤1.002H / m; when the height of the stretched product is 2.5-10cm, the magnetic permeability of the product is ≤1.03H / m.

[0030] By adopting the above technical solution, when the thickness of the non-magnetic stainless steel is 0.1-0.6mm, the permeability is controlled at ≤1.002H / m, giving the non-magnetic stainless steel good non-magnetic properties; when the height of the stretched product is 2.5-10cm, the permeability is controlled at ≤1.03H / m, indicating that the non-magnetic stainless steel can maintain stable magnetic properties even with a high stretching height, meeting the needs of fields with high requirements for product dimensional accuracy, high sensitivity, and high stability.

[0031] Secondly, this application provides a process for preparing non-magnetic stainless steel, which adopts the following technical solution: A process for preparing non-magnetic stainless steel includes the following steps: S1. Smelting: Iron, chromium, nickel, manganese and carbon are added to an electric arc furnace for smelting to produce molten steel; S2. Refining: Add molten steel to a refining furnace and add copper, cobalt, vanadium, molybdenum, titanium, niobium, tungsten, nitrogen, tin, aluminum, silicon and boron for refining. Use a dolomite ladle and refine and remove impurities under argon or nitrogen conditions. Control the sulfur content to ≤0.01% and the phosphorus content to ≤0.04%. S3. Casting: The refined molten steel is cast into a billet and then cooled. S4. Hot rolling: The cooled casting billet is rough rolled and finish rolled, then cooled to obtain a steel plate; S5. Cold rolling: Cold rolling is the process of cold rolling hot-rolled steel plates. S6. Annealing: Annealing cold-rolled steel sheets; S7. Pickling and passivation: Annealed steel plates are pickled and passivated to obtain non-magnetic stainless steel.

[0032] By adopting the above technical solution, in step S1, iron, chromium, nickel, manganese, and carbon are added to an electric arc furnace for smelting to produce molten steel, which allows for the initial fusion of the basic components; in step S2, multiple elements are added to a refining furnace for refining, and a dolomite ladle is used to remove impurities under argon or nitrogen conditions, controlling the sulfur and phosphorus content, which optimizes the steel composition, improves the purity of the molten steel, and helps to improve the quality of non-magnetic stainless steel; in step S3, the refined molten steel is cast into a billet and cooled, shaping the molten steel into a billet form that facilitates subsequent processing; in step S4... Step S1 involves rough rolling and finish rolling the cooled billet to change its thickness and shape, producing a steel plate of the required specifications. Step S5 involves cold rolling the hot-rolled steel plate to further refine its thickness and surface quality. Step S6 involves annealing the cold-rolled steel plate to eliminate internal stress, improve its microstructure, and enhance its toughness and stability. Step S7 involves pickling and passivating the annealed steel plate to remove surface impurities and oxide layers, improving the corrosion resistance of the non-magnetic stainless steel, ultimately producing a high-performance non-magnetic stainless steel.

[0033] Preferably, the melting temperature in step S1 is 1500-1600℃ and the melting time is 2-4h; the refining temperature in step S2 is 1550-1650℃ and the refining time is 1-2h.

[0034] By adopting the above technical solutions, the superior melting and refining conditions help the components to fully fuse and react, making the composition more uniform and forming a more stable non-magnetic stainless steel metal phase structure. This improves the comprehensive properties of non-magnetic stainless steel, such as strength, hardness, toughness, ductility, and corrosion resistance. At the same time, it precisely controls the content of impurities such as sulfur and phosphorus, reduces the adverse effects of impurities on the performance of stainless steel, ensures the high quality and stability of non-magnetic stainless steel, and also ensures a low magnetic permeability.

[0035] Preferably, in step S4, the hot-rolled flavor roughing and finishing rolling are performed with a roughing temperature of 1150℃-1250℃ and a thickness deformation rate of 40-50%; and a finishing temperature of 900℃-1000℃ and a thickness deformation rate of 30-40%.

[0036] By adopting the above technical solutions, the rough rolling temperature is controlled at 1150℃-1250℃, and the thickness deformation is controlled at 40-50%. This temperature range helps to give the billet good plasticity. Rough rolling at this temperature can effectively change the shape and size of the billet. The larger thickness deformation allows the billet to initially reach the required approximate specifications, laying a good foundation for the subsequent finish rolling process. The finish rolling temperature is controlled at 900℃-1000℃, and the thickness deformation rate is controlled at 30-40%. This temperature range is conducive to accurately controlling the thickness, flatness, and surface quality of the steel plate. The appropriate temperature ensures that the microstructure of the steel plate changes uniformly during the finish rolling process, and the reasonable thickness deformation rate allows the steel plate to achieve high-precision dimensional requirements, ensuring that the final steel plate meets high-quality standards.

[0037] Preferably, the cold rolling temperature in step S5 is 700℃-800℃, and the thickness deformation rate is 60-70%.

[0038] By adopting the above technical solutions, optimizing the temperature and thickness deformation rate of cold rolling helps to ensure that non-magnetic stainless steel has suitable plasticity and toughness, avoiding the material being too hard and difficult to process due to excessively low temperature, or the grains being too coarse due to excessively high temperature, which affects performance. The thickness deformation rate enables non-magnetic stainless steel to obtain better microstructure and properties during cold rolling, refines the grains, improves the strength and hardness of the material, while ensuring that it has good elongation and corrosion resistance, and is also conducive to controlling the dimensional accuracy of the product.

[0039] Preferably, the annealing temperature in step S6 is 850-900℃ and the annealing time is 1-2h.

[0040] By adopting the above technical solutions, the superior annealing conditions help to eliminate the internal stress generated during cold rolling, restore the plasticity and toughness of non-magnetic stainless steel, and make the microstructure of non-magnetic stainless steel more uniform and stable.

[0041] Thirdly, this application provides an application of non-magnetic stainless steel, employing the following technical solution: An application of non-magnetic stainless steel is presented, used in sensors, motor housings, shielding covers, communication cards, and antenna housings. By adopting the above technical solution, the problem of balancing strength, hardness, ductility, corrosion resistance, and magnetic permeability when using low-nickel austenitic stainless steel in fields requiring high dimensional accuracy, sensitivity, and stability is solved. This allows non-magnetic stainless steel to be used in high-performance applications such as sensors, motor housings, communication base stations, signal shielding, vacuum magnetrons, and magnetic switches, thanks to its excellent non-magnetic properties, high toughness, corrosion resistance, and stability.

[0042] In summary, this application includes at least one of the following beneficial technical effects: 1. The non-magnetic stainless steel of this application comprises: 16-16.5% chromium, 11-12% manganese, 5.9-6.4% nickel, 0.1-0.3% copper, 0.12-0.22% cobalt, 0.1-0.2% vanadium, 0.1-0.2% molybdenum, 0.05-0.1% carbon, 0.2-0.4% titanium, 0.2-0.5% silicon, ≤0.04% phosphorus, ≤0.01% sulfur, 0.04-0.09% niobium, 0.02-0.06% tungsten, 0.008-0.018% aluminum, 0.03-0.09% nitrogen, and 0.0% tin. The ratio of 0.003-0.008% nickel, 0.002-0.005% boron, and the balance iron and unavoidable impurities ensures the strength, hardness, toughness, and corrosion resistance of non-magnetic stainless steel while reducing the nickel content. This solves the problem of balancing strength, hardness, ductility, corrosion resistance, and magnetic permeability when existing low-nickel austenitic stainless steels are used in fields requiring high dimensional accuracy, high sensitivity, and high stability. It is suitable for applications such as sensors, motor housings, communication base stations, signal shielding, vacuum magnetrons, and magnetic switches.

[0043] 2. Optimizing the titanium to carbon ratio: A titanium to carbon ratio of 5:1 significantly refines the grains and improves the mechanical properties of non-magnetic stainless steel. A titanium to carbon ratio of 3:1 results in the highest creep resistance. This prevents the precipitation of chromium carbide along the austenite grain boundaries during heating, thereby reducing creep deformation and improving both the magnetic properties and mechanical properties and ductility of the non-magnetic stainless steel.

[0044] 3. The preparation process of the non-magnetic stainless steel of this application, through smelting, refining, casting, hot rolling, cold rolling, annealing, pickling and passivation processes, produces non-magnetic stainless steel with excellent comprehensive mechanical properties and magnetic stability. Detailed Implementation

[0045] The present application will be further described in detail below with reference to the embodiments. Example

[0046] Example 1 Example 1 discloses a non-magnetic stainless steel, composed of the following components by weight percentage: chromium 16%, manganese 11%, nickel 6.4%, copper 0.1%, cobalt 0.22%, vanadium 0.15%, molybdenum 0.1%, carbon 0.05%, titanium 0.3%, silicon 0.2%, phosphorus 0.02%, sulfur 0.01%, niobium 0.09%, tungsten 0.02%, aluminum 0.018%, nitrogen 0.03%, tin 0.008%, boron 0.005%, lead 0.002%, and iron 65.277%.

[0047] This non-magnetic stainless steel is prepared by the following steps: S1. Smelting: Iron, chromium, nickel, manganese and carbon are added to an electric arc furnace for smelting. The smelting temperature is controlled at 1500℃ and smelting is carried out for 4 hours to produce molten steel. S2. Refining: Add molten steel to a refining furnace and add copper, cobalt, vanadium, molybdenum, titanium, niobium, tungsten, nitrogen, tin, aluminum, silicon and boron for refining. Use a dolomite ladle and refine and remove impurities under argon conditions. Control the sulfur content to ≤0.01% and the phosphorus content to ≤0.04%. S3. Casting: The refined molten steel is cast into a billet and then cooled. S4. Hot rolling: The cooled billet is subjected to rough rolling and finish rolling. The rough rolling temperature is controlled at 1150℃, and the thickness deformation rate of the rough rolled billet is 50%. The finish rolling temperature is 900℃, and the thickness deformation rate of the finish rolled billet is 30%. After cooling, a steel plate is obtained. S5. Cold rolling: The hot-rolled steel plate is cold-rolled, and the cold rolling temperature is controlled at 700℃. The thickness deformation rate of the cold-rolled steel plate is 70%. S6. Annealing: The cold-rolled steel sheet is annealed, with the annealing temperature controlled at 850℃ and the annealing time at 1.5h. S7. Pickling and passivation: The annealed steel plate is pickled and passivated. The pickling time is 15 minutes, the pickling temperature is 55℃, the passivation time is 5 minutes, and the passivation temperature is 25℃ to obtain non-magnetic stainless steel. Pickling uses commercially available stainless steel pickling agent, any model; passivation uses commercially available stainless steel passivation solution, model Guangdong Kaimeng ID3000-1.

[0048] Example 2-3 The difference between Examples 2-3 and Example 1 lies in the amount of raw materials used and the preparation conditions, as detailed in Table 1 below.

[0049] Table 1 Parameter table for Examples 1-3 Example 4 The difference between Example 4 and Example 1 is that titanium is 0.3%, carbon is 0.1%, and iron is 65.227%, while the rest is the same as in Example 1.

[0050] Example 5 The difference between Example 5 and Example 1 is that the amount of titanium is 0.375%, carbon is 0.075%, and iron is 65.177%, while the rest is the same as in Example 1.

[0051] Example 6 The difference between Example 6 and Example 4 is that the non-magnetic stainless steel is composed of the following components by weight percentage: chromium 16.3%, manganese 11.4%, nickel 6%, copper 0.2%, cobalt 0.16%, vanadium 0.15%, molybdenum 0.12%, carbon 0.075%, titanium 0.375%, silicon 0.4%, phosphorus 0.02%, sulfur 0.01%, niobium 0.05%, tungsten 0.02%, aluminum 0.01%, nitrogen 0.03%, tin 0.005%, boron 0.004%, lead 0.002%, and iron 64.669%.

[0052] Example 7 The difference between Example 7 and Example 4 is that the non-magnetic stainless steel is composed of the following components by weight percentage: chromium 16.5%, manganese 11.6%, nickel 6.1%, copper 0.3%, cobalt 0.18%, vanadium 0.2%, molybdenum 0.15%, carbon 0.075%, titanium 0.375%, silicon 0.5%, phosphorus 0.02%, sulfur 0.01%, niobium 0.07%, tungsten 0.04%, aluminum 0.03%, nitrogen 0.06%, tin 0.003%, boron 0.002%, lead 0.002%, and iron 63.783%.

[0053] Comparative Example Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that nitrogen is 0.18%, manganese is 13.8%, and iron is 62.327%, while the rest is the same as in Example 1.

[0054] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the molybdenum content is 1.6% and the iron content is 63.777%, while the rest is the same as in Example 1.

[0055] Comparative Example 3 The difference between Comparative Example 3 and Comparative Example 2 is that niobium is 0.6% and iron is 63.267%, while the rest is the same as Comparative Example 2.

[0056] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that vanadium is 1% and iron is 64.427%, while the rest is the same as in Example 1.

[0057] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that cobalt is 0.8% and iron is 64.697%, while the rest is the same as in Example 1.

[0058] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is that nickel is 3% and iron is 68.677%, while the rest is the same as in Example 1.

[0059] Comparative Example 7 The difference between Comparative Example 7 and Example 1 is that nickel is 10% and iron is 61.677%, while the rest is the same as in Example 1.

[0060] Comparative Example 8 The difference between Comparative Example 8 and Example 1 is that boron is replaced with an equal amount of tin, otherwise it is the same as Example 1.

[0061] Comparative Example 9 The difference between Comparative Example 9 and Example 1 is that aluminum is replaced with an equal amount of titanium, otherwise the same as Example 1.

[0062] Performance testing The following performance tests were conducted on Examples 1-7 and Comparative Examples 1-9: Non-magnetic stainless steel with a thickness of 0.4 mm and a width of 82 mm was used as the test sample.

[0063] 1. Mechanical property testing According to the test methods in GB / T 228.1-2021, the yield strength (unit: MPa), tensile strength (unit: MPa) and elongation (unit: %) of non-magnetic stainless steel were tested, and the test results were recorded.

[0064] 2. Vickers hardness: Use a Vickers hardness tester to test the hardness (unit: HV) of non-magnetic stainless steel, and record the test results.

[0065] 3. Corrosion resistance: The test was conducted using a salt spray corrosion testing machine. Test conditions: 50 g / L sodium chloride solution, test chamber temperature 35℃, saturation tank temperature 47℃, sedimentation rate 2 mL / (h, 80 cm³) 2 The collected solution had a pH of 6.9 and was tested for 240 hours. The surface appearance grade was determined according to Clause 6.2 of GB / T 10125-2021, with grade 10 being the best and grade 0 the worst. The results were tested and recorded.

[0066] The following are the performance test data for Examples 1-7 and Comparative Examples 1-9, as detailed in Table 2.

[0067] Table 2 Performance data of Examples 1-7 and Comparative Examples 1-9 Based on Examples 1-3 and Examples 4-7 and Table 2, it can be concluded that by optimizing the proportion of each component element in this application, the mechanical properties of the obtained non-magnetic stainless steel can be improved while its ductility is also enhanced.

[0068] Based on Examples 1 and 1 (Comparative Example), and referring to Table 2, it can be concluded that in Comparative Example 1, increasing the proportion of nitrogen and manganese resulted in a decrease in the yield strength and tensile strength of the non-magnetic stainless steel, a slight increase in hardness, and a decrease in elongation. This is likely due to the precipitation of nitrides formed by excessive nitrogen, manganese, and chromium, which reduces the strain properties of the non-magnetic stainless steel and also decreases its corrosion resistance. In Comparative Example 2, increasing the amount of molybdenum resulted in a decrease in the yield strength and tensile strength of the non-magnetic stainless steel, a slight increase in hardness, and a decrease in elongation. This is likely due to the precipitation of metallic compounds formed by excessive molybdenum in the system, which reduces the strength properties of the non-magnetic stainless steel and also decreases its corrosion resistance. In Comparative Example 3, increasing the amount of niobium compared to Comparative Example 2 resulted in a decrease in the performance of the non-magnetic stainless steel. This is likely because it disrupts the optimal ratio of niobium to molybdenum in the non-magnetic stainless steel, thereby reducing its mechanical strength and elongation. Corrosion resistance also decreased. In Comparative Examples 4 and 5, changing the amounts of vanadium and cobalt resulted in a decrease in the performance of the non-magnetic stainless steel. In Comparative Examples 6-7, the nickel content was varied. When the nickel content was too low, the ductility and corrosion resistance decreased significantly; when the nickel content was too high, although the ductility increased, the mechanical strength and hardness decreased significantly. In Comparative Example 8, replacing boron with tin reduced both mechanical properties and ductility. In Comparative Example 9, replacing aluminum with titanium reduced the mechanical properties, ductility, and corrosion resistance of the resulting non-magnetic stainless steel.

[0069] 4. Testing of magnetic permeability of non-magnetic stainless steel and magnetic permeability of the product after stretching: The automotive ABS sensor housing is prepared by stretching non-magnetic stainless steel. The automotive ABS sensor housing has a hollow cylindrical structure with a stretching height of 25 mm, a wall thickness of 0.33 mm, and an inner diameter of 7 mm.

[0070] The permeability of non-magnetic stainless steel and stretched products was tested using a permeability meter (unit: H / m), and the test results were recorded.

[0071] The following are the test results of the magnetic permeability of Examples 1, 4, 7, Comparative Examples 1-2, Comparative Examples 6 and 8. Please refer to Table 3 for details.

[0072] Table 3. Data from Examples 1, 4, 7, Comparative Examples 1-2, 6, and 8 Based on Examples 1-3, Comparative Examples 1-2, 6, and 8, and Table 3, it can be concluded that the magnetic permeability of the non-magnetic stainless steel using this application is within 1.002H / m, and the magnetic permeability of the stretched product is within 1.03H / m.

[0073] In Comparative Example 1, increasing the proportion of nitrogen and manganese improved the permeability of the non-magnetic stainless steel. The permeability changed significantly after stretching, possibly because the precipitation of nitrides formed by excessive nitrogen, manganese, and chromium reduced the magnetic stability of the austenitic stainless steel structure. In Comparative Example 2, increasing the proportion of molybdenum improved the permeability of the non-magnetic stainless steel. The permeability changed significantly after stretching, possibly because the precipitation of metallic compounds formed by excessive molybdenum in the system affected the formation of the austenitic metallic phase, thus affecting the magnetic stability of the non-magnetic stainless steel. In Comparative Example 6, reducing the nickel content improved the permeability of the non-magnetic stainless steel. The permeability changed significantly after stretching. In Comparative Example 8, replacing boron with an equal amount of tin improved the permeability of the non-magnetic stainless steel. The permeability changed significantly after stretching, possibly because the absence of boron reduced the synergistic effect of boron with nickel, chromium, and molybdenum, disrupting the metallic phase of the austenitic stainless steel and thus reducing the magnetic stability of the non-magnetic stainless steel.

[0074] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A non-magnetic stainless steel, characterized by, The steel is prepared from the following raw materials in weight percentage: chromium 16-16.5%, manganese 11-12%, nickel 5.9-6.4%, copper 0.1-0.3%, cobalt 0.12-0.22%, vanadium 0.1-0.2%, molybdenum 0.1-0.2%, carbon 0.05-0.1%, titanium 0.2-0.4%, silicon 0.2-0.5%, phosphorus ≤0.04%, sulfur ≤0.01%, niobium 0.04-0.09%, tungsten 0.02-0.06%, aluminum 0.008-0.018%, nitrogen 0.03-0.09%, tin 0.003-0.008%, boron 0.002-0.005%, and the balance of iron and inevitable impurities.

2. A non-magnetic stainless steel according to claim 1, characterized by The weight ratio of titanium and carbon is (3-5):

1.

3. A non-magnetic stainless steel according to claim 1 or 2, characterized in that, The steel is prepared from the following raw materials in weight percentage: chromium 16.3-16.5%, manganese 11.4-11.6%, nickel 6-6.1%, copper 0.2-0.3%, cobalt 0.16-0.18%, vanadium 0.15-0.2%, molybdenum 0.12-0.15%, carbon 0.075-0.1%, titanium 0.3-0.375%, silicon 0.4-0.5%, phosphorus ≤0.04%, sulfur ≤0.01%, niobium 0.05-0.07%, tungsten 0.02-0.04%, aluminum 0.01-0.013%, nitrogen 0.03-0.06%, tin 0.003-0.005%, boron 0.002-0.004%, and the balance of iron and inevitable impurities.

4. A non-magnetic stainless steel according to claim 1, characterized by When the thickness of the non-magnetic stainless steel is 0.1-0.6mm, the magnetic permeability of the non-magnetic stainless steel is ≤1.002H / m; the height of the product after stretching is 2.5-10cm, and the magnetic permeability of the product is ≤1.03H / m.

5. A process for the production of a non-magnetic stainless steel as claimed in any one of claims 1 to 4, characterized in that, The method comprises the following steps: S1, melting: iron, chromium, nickel, manganese and carbon are added to an electric arc furnace for melting to prepare molten steel; S2, refining: the molten steel is added to a refining furnace, and copper, cobalt, vanadium, molybdenum, titanium, niobium, tungsten, nitrogen, tin, aluminum, silicon and boron are added for refining, white dolomite ladle is used, and refining is carried out under the condition of argon or nitrogen, and impurities are removed, the sulfur content is controlled to be ≤0.01%, and the phosphorus content is controlled to be ≤0.04%; S3, casting: the refined molten steel is cast into a cast blank and cooled; S4, hot rolling: the cooled cast blank is coarsely rolled and finely rolled to prepare a steel plate; S5, cold rolling: the hot-rolled steel plate is subjected to cold rolling treatment; S6, annealing: the cold-rolled steel plate is subjected to annealing treatment; S7, pickling and passivation: the annealed steel plate is subjected to pickling and passivation to prepare a non-magnetic stainless steel.

6. A process for the production of a non-magnetic stainless steel according to claim 5, characterized in that, The melting temperature in the S1 step is 1500-1600℃, and the melting time is 2-4h; the refining temperature in the S2 step is 1550-1650℃, and the refining time is 1-2h.

7. The process for producing a non-magnetic stainless steel according to claim 5, wherein The hot rolling in the S4 step is divided into coarse rolling and fine rolling, the temperature of the coarse rolling is 1150℃-1250℃, and the thickness deformation rate is 40-50%; the temperature of the fine rolling is 900℃-1000℃, and the thickness deformation rate is 30-40%.

8. The process for producing a non-magnetic stainless steel according to claim 5, wherein The temperature of the cold rolling in the S5 step is 700℃-800℃, and the thickness deformation rate is 60-70%.

9. The process for producing a non-magnetic stainless steel according to claim 5, wherein The annealing temperature in S6 is 850-900 DEG C, and the annealing time is 1-2 hours.

10. Use of a non-magnetic stainless steel according to any one of claims 1-4, characterized in that, It is applied to sensor, motor shell, communication base station, signal shielding, vacuum magnetron and magnetic control switch.

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