High antimagnetic stainless steel and preparation method thereof

Abstract

The present invention relates to the field of stainless steel and discloses a high-diamagnetic stainless steel and a preparation method thereof. The high-diamagnetic stainless steel comprises the following raw materials in percentage: 0.01%-0.03% carbon, 0.2%-0.3% silicon, 11.5%-12.3% manganese, ≤0.04% phosphorus, ≤0.03% sulfur, 10%-14% nickel, 18.0%-20% chromium, 0.1%-1% copper, 0.15%-0.2% nitrogen, 1%-2% titanium, 1%-3% niobium, and 2%-3% molybdenum, with the remainder being iron. Nickel is a key element for the formation and stabilization of austenite. The presence of a large amount of nickel promotes the formation of a stable austenite structure. The good diamagnetic properties of the austenite phase are the basic guarantee, thereby solving the problem that conventional stainless steel generates significant magnetism after deep drawing, causing such materials to fail magnetic inspections in various transportation vehicles and supermarkets.

Description

Technical Field

[0001] The present invention relates to the technical field of stainless steel, in particular to high antimagnetic stainless steel and a preparation method thereof. Background Art

[0002] In modern industry, stainless steel, as a key metal material, is widely used in a variety of industries, including construction, machinery manufacturing, chemicals, and food processing. Its excellent corrosion resistance, high strength, and good processability meet the stringent material performance requirements in various scenarios. With the continuous advancement of industrial technology and the increasing diversification of market demands, the performance requirements for stainless steel are becoming increasingly stringent. Not only must it maintain stable performance under conventional conditions, but it must also demonstrate excellent adaptability under complex and harsh working conditions.

[0003] Although traditional stainless steel is non-magnetic in nature, it will produce obvious magnetism after deep drawing, causing this type of material to fail magnetic inspections during security checks on various means of transportation and in places such as supermarkets. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a high-antimagnetic stainless steel and a preparation method thereof, which solves the problem that although traditional stainless steel is non-magnetic in itself, it will produce obvious magnetism after deep drawing, causing such materials to fail magnetic inspections in security inspections of various means of transportation and in security inspections in supermarkets and other places.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: a high antimagnetic stainless steel, comprising the following percentages of raw materials: carbon 0.01%-0.03%, silicon 0.2%-0.3%, manganese 11.5%-12.3%, phosphorus ≤0.04%, sulfur ≤0.03%, nickel 10%-14%, chromium 18.0%-20%, copper 0.1%-1%, nitrogen 0.15%-0.2%, titanium 1%-2%, niobium 1%-3% and molybdenum 2%-3%, with the remainder being iron.

[0006] A method for preparing high antimagnetic stainless steel comprises the following steps:

[0007] S1. Raw material preparation: take the raw materials according to percentage and pre-process them;

[0008] S2. Melting: adding the pretreated raw materials into an electric arc furnace for melting to obtain a raw material solution;

[0009] S3, refining: using argon oxygen decarburization process to refine the raw material solution to obtain molten steel;

[0010] S4, casting: casting the molten steel into the continuous casting machine, and controlling the solidification process of the ingot by adjusting the cooling water volume and casting speed to obtain a steel ingot;

[0011] S5, hot rolling: the steel billet is heated gradually in different zones, and after high pressure descaling, rough rolling and finish rolling are carried out. After laminar cooling, the steel billet is coiled to obtain hot rolled black coil;

[0012] S6, solution pickling: the hot-rolled black coil is subjected to solution treatment, shot blasting and scale breaking, and then enters pickling treatment to obtain the hot-rolled white coil;

[0013] S7. Cold rolling: The hot-rolled white coil is rolled on a continuous rolling mill / a twenty-high single rolling mill to obtain a chilled coil. After surface degreasing and solution treatment, it enters electrolysis and pickling treatment, and after online leveling and straightening treatment, it obtains a cold-rolled 2B surface steel coil.

[0014] Preferably, the pretreatment in S1 includes crushing the bulk raw material to a particle size of 6-9 mm.

[0015] Preferably, the smelting temperature in S2 is 1520-1630° C., and the smelting time is 70-110 minutes.

[0016] Preferably, the refining temperature in S3 is 1510-1540° C., and the refining time is 35-55 minutes.

[0017] Preferably, the casting speed of the molten steel into the continuous casting machine in S4 is 0.9-1.4m / min, and the cooling water volume is 6-14m 3 / h, and the pulling speed is 0.9-1.1m / min.

[0018] Preferably, the heating temperature in S5 is 1090-1110° C., the heating time is 40-80 minutes, the number of hot rolling deformation passes is 9-11, and the deformation amount of each pass is 8.5-9.5%.

[0019] Preferably, the solution treatment in S6 is to heat the material to a solution temperature of 1070-1085°C at a rate of 13-17°C / s, and keep the temperature for 1.6-1.9 minutes per millimeter of thickness, and then cool the material by air cooling, mist cooling and water cooling in sequence, with a cooling rate of 105-115°C / s.

[0020] Preferably, the total deformation of the cold rolling in S7 is 57-63%, the surface degreasing uses a professional degreasing agent, the conductivity of the degreasing liquid is controlled at 6-9ms / cm, and the temperature is controlled at 65-75°C, the solution treatment is to heat the temperature to the solution temperature of 1070-1095°C at a rate of 13-17°C / s, and the insulation time is 1.6-1.9 minutes per millimeter thickness, and then air cooling, mist cooling, and water cooling are used in sequence for cooling, and the cooling rate is 105-115°C / s, the current of the electrolysis is controlled at 3800-4200A, and the temperature is controlled at 68-72°C, the flattening elongation is greater than 0.30%, and the elongation of the tension straightening is greater than 0.32%.

[0021] The present invention provides a high-antimagnetic stainless steel and a preparation method thereof. It has the following beneficial effects:

[0022] 1. This invention utilizes nickel as a key element for austenite formation and stabilization. Its presence in large quantities promotes the formation of a stable austenite structure, providing a fundamental guarantee for the excellent antimagnetic properties of the austenite phase. Manganese partially replaces nickel to stabilize the austenite structure and expand its phase range, synergistically enhancing antimagnetic properties with nickel. Nitrogen, an austenite-forming element, dissolves in the austenite to stabilize the structure and further enhance antimagnetic properties. Strictly controlling the carbon content reduces carbide formation, preventing magnetic changes caused by carbides affecting austenite uniformity. Titanium and niobium, strong carbide-forming elements, are added to preferentially bind with carbon, preventing the precipitation of chromium carbides, refining the grain size for a more uniform structure, and reducing magnetic anomalies. These elements work together to stabilize the austenite structure, reduce the impact of carbides, and refine the grain size. This solves the problem that conventional stainless steel, while inherently nonmagnetic, develops significant magnetism after deep drawing, causing such materials to fail magnetic inspections in various transportation vehicles and supermarkets.

[0023] 2. The dense chromium oxide protective film formed on the surface of stainless steel by chromium in the present invention can effectively resist the erosion of external media; molybdenum can enhance the corrosion resistance of stainless steel in reducing media, improve the resistance to pitting and crevice corrosion, and synergistically improve the stability of stainless steel in harsh corrosive environments with chromium; copper can improve the atmospheric corrosion resistance and cold working performance of stainless steel, further enhancing the overall corrosion resistance.

[0024] 3. By strictly controlling phosphorus and sulfur contents (≤0.04% and ≤0.03%, respectively), this invention effectively avoids their adverse effects on the steel's plasticity, toughness, and weldability, ensuring excellent processing properties. Furthermore, by partially replacing nickel with manganese, the use of expensive nickel is reduced while maintaining the stainless steel's basic properties, lowering production costs and expanding the stainless steel's application in cost-sensitive applications.

[0025] 4. The present invention provides a high-quality foundation for subsequent processes through raw material preparation. Smelting ensures full fusion of raw materials, refining removes impurities and accurately adjusts the composition to improve the purity of molten steel, casting accurately controls various parameters to obtain ingots with uniform structure, hot rolling refines grains and improves structure, solid solution optimizes microstructure and eliminates stress, and cold working improves surface quality and dimensional accuracy, thereby preparing plate and strip steel with precise composition, uniform structure and excellent comprehensive performance. While ensuring strength and hardness, it significantly improves corrosion resistance and stress corrosion resistance, optimizes processing performance, and reduces production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a flow chart of a method for preparing high antimagnetic stainless steel proposed in the present invention. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] Please see the attached Figure 1 An embodiment of the present invention provides a high antimagnetic stainless steel, comprising the following percentages of raw materials: carbon 0.01%-0.03%, silicon 0.2%-0.3%, manganese 11.5%-12.3%, phosphorus ≤0.04%, sulfur ≤0.03%, nickel 10%-14%, chromium 18.0%-20%, copper 0.1%-1%, nitrogen 0.15%-0.2%, titanium 1%-2%, niobium 1%-3% and molybdenum 2%-3%, with the remainder being iron.

[0029] Specifically, through the mutual cooperation of various raw materials, a complex and stable alloy system is formed. The various elements work synergistically to give full play to their own advantages and make up for each other's shortcomings. Elements such as carbon, silicon, and manganese play a significant synergistic role in improving the strength and hardness of stainless steel. The carbon content is precisely controlled at 0.01%-0.03%. While enhancing the strength and hardness, it avoids intergranular corrosion and magnetic unevenness caused by excessive precipitation of carbides, and maintains the good toughness and welding performance of stainless steel. The addition of silicon is 0.2%-0.3%. As an effective deoxidizer, it not only enhances the strength and hardness of steel, but also improves its antioxidant properties. Working together with carbon, it further enhances the overall mechanical properties of stainless steel without affecting other key properties. Manganese, at a content of 11.5%-12.3%, partially replaces nickel to stabilize the austenite structure and enhance antimagnetism, while also mitigating the adverse effects of sulfur on steel properties. This improves the steel's strength, hardness, and workability, synergizing with carbon and silicon to comprehensively enhance the mechanical properties of stainless steel. Nickel, chromium, copper, nitrogen, and molybdenum also contribute to stainless steel's corrosion resistance. Chromium, a key element in stainless steel's corrosion resistance, forms a dense protective chromium oxide film at a content of 18.0%-20%, effectively shielding it from external media. This is the foundation of stainless steel's excellent corrosion resistance. Nickel, at a content of 10%-14%, not only forms and stabilizes the austenite structure, enhancing antimagnetism, but also expands the austenite phase, further enhancing corrosion resistance. Copper, at a content of 0.1%-1%, enhances stainless steel's atmospheric corrosion resistance and cold working properties, while also improving its machinability to a certain extent, further enhancing corrosion resistance. Nitrogen is added in an amount of 0.15%-0.2%. As an austenite-forming element, it improves the strength and hardness of stainless steel without reducing plasticity and toughness. Its dissolution in austenite helps stabilize the structure, thereby improving corrosion resistance. Molybdenum content is 2%-3%, which can significantly enhance the corrosion resistance of stainless steel in reducing media (such as dilute sulfuric acid, hydrochloric acid, etc.), improve its resistance to pitting and crevice corrosion, and synergize with chromium to further improve the stability of stainless steel in harsh corrosive environments. Titanium and niobium, as strong carbide-forming elements, are added in amounts of 1%-2% and 1%-3% respectively. They can preferentially combine with carbon to form stable carbides, prevent the precipitation of chromium carbides, and avoid the occurrence of intergranular corrosion. At the same time, they refine the grains and improve the strength and toughness of the steel. The phosphorus and sulfur contents are strictly controlled at ≤0.04% and ≤0.03% respectively, effectively avoiding their significant damage to the plasticity, toughness and welding performance of the steel, and ensuring that the stainless steel has good processing properties; more importantly, elements such as nickel, manganese, and nitrogen play a key role in stabilizing the austenitic structure, thereby effectively improving the anti-magnetic properties of stainless steel.Nickel, a primary element for forming and stabilizing austenite, contributes significantly to the formation of a stable austenitic structure in stainless steel. Austenite typically exhibits excellent antimagnetic properties, making it a key factor in achieving high antimagnetic properties. Manganese can partially replace nickel to stabilize the austenite structure, expanding the austenite phase to a certain extent. This synergistic effect, along with nickel, promotes austenite formation and enhances antimagnetic properties. Nitrogen, an austenite-forming element, dissolves in austenite, helping to stabilize the structure and further improve the antimagnetic properties of stainless steel. This synergistic effect effectively addresses the problem of traditional stainless steel developing significant magnetism after deep drawing, which prevents it from passing magnetic inspections in transportation security checks and supermarkets.

[0030] A method for preparing high antimagnetic stainless steel comprises the following steps:

[0031] S1. Raw material preparation: The raw materials are taken according to percentage and pre-processed; the pre-processing in S1 includes crushing the block raw materials to a particle size of 6-9 mm.

[0032] Specifically, by taking raw materials according to percentages and pre-treating them, the uniform distribution of various elements during subsequent processing is ensured, avoiding uneven composition due to differences in raw material particle size and impurities. The bulk raw materials are crushed to a particle size of 6-9mm, which not only facilitates rapid melting during smelting, but also ensures full contact with other raw materials during mixing, improving mixing uniformity. Surface cleaning of easily oxidizable raw materials removes the oxide layer, preventing oxidized impurities from mixing into the molten steel during smelting, affecting its purity and composition accuracy. This provides high-quality, precisely formulated, and uniform raw materials for subsequent smelting processes, laying a solid foundation for the production of high-antimagnetic stainless steel that meets stable performance requirements.

[0033] S2. Melting: The pretreated raw materials are sequentially added into an electric arc furnace for melting to obtain a raw material solution; the melting temperature in S2 is 1520-1630° C., and the melting time is 70-110 minutes.

[0034] Specifically, the pretreated raw materials are sequentially added to an electric arc furnace for smelting to obtain a raw material solution, thereby fully fusing the various raw materials under high temperature. In a specific order, the majority of the iron material is added first to build the basic framework for the alloy system. Then, alloying materials such as ferromanganese and ferrochrome are added, allowing them to gradually dissolve and diffuse. Finally, precious alloying elements such as nickel and copper are added to ensure their uniform distribution. At high temperatures of 1520-1630°C, the activity of atoms is enhanced, accelerating the diffusion and fusion between elements. The smelting time is controlled at 70-110 minutes to ensure the full progress of the reaction. Through precise control of temperature and time, the raw materials are uniformly mixed at the atomic level, resulting in a raw material solution with uniform composition that meets the requirements of high-antimagnetic stainless steel. This provides good starting materials for the subsequent refining process to remove impurities and precisely adjust the composition, ensuring that the final high-antimagnetic stainless steel has stable and excellent performance.

[0035] S3, refining: the raw material solution is refined by argon oxygen decarburization process to obtain molten steel; the refining temperature in S3 is 1510-1540°C, and the refining time is 35-55 minutes.

[0036] Specifically, the raw material solution is refined using an argon-oxygen decarburization process to produce molten steel. This process utilizes the synergistic effect of oxygen and argon to effectively remove carbon and other impurities from the raw material solution. In the initial refining stage, the oxygen-to-argon flow ratio is controlled at 3:1-4:1. The high oxygen content promotes rapid oxidation of carbon to gases such as carbon monoxide, achieving rapid decarburization. As refining progresses, when the carbon content in the molten steel drops to 0.1%-0.15%, the oxygen-to-argon flow ratio is adjusted to 2:1-3:1 to prevent excessive oxidation of other alloying elements. A refining temperature of 1510-1540°C effectively ensures the chemical reaction rate while avoiding the adverse effects of excessive temperatures on equipment and alloying elements. Refining time is controlled at 35-55 minutes to ensure sufficient decarburization and impurity removal reactions. By precisely controlling the temperature, time, and gas flow rate, the carbon content in the molten steel can be reduced, harmful impurities such as sulfur and phosphorus can be removed, and the purity of the molten steel can be improved. This provides molten steel with precise composition and high purity for subsequent casting processes, creating favorable conditions for the preparation of high-performance and high-antimagnetic stainless steel.

[0037] S4, casting: casting the molten steel into the continuous casting machine, and controlling the solidification process of the ingot by adjusting the cooling water volume and the pulling speed to obtain the steel ingot; the casting speed of the molten steel into the continuous casting machine in S4 is 0.9-1.4m / min, and the cooling water volume is 6-14m 3 / h, and the pulling speed is 0.9-1.1m / min.

[0038] Specifically, by preheating the mold of the continuous casting machine at 150-200℃ for 2-4 hours, the temperature difference between the mold and the molten steel is reduced, preventing the molten steel from generating excessive thermal stress due to sudden cooling in the early stage of casting, and reducing the possibility of defects such as cracks in the steel billet. The molten steel is then poured into the mold of the continuous casting machine at a speed of 0.9-1.4m / min to ensure that the molten steel can fill the mold smoothly and continuously. During the casting process, the molten steel is poured at a speed of 6-14m / min. 3 The solidification process of the ingot is controlled in a coordinated manner by a cooling water volume of 0.9-1.1 m / min and a pulling speed of 0.9-1.1 m / min. The cooling water volume determines the solidification rate of the molten steel, and the pulling speed matches the cooling rate to ensure that the ingot maintains a uniform microstructure during the solidification process. When the cooling water volume is large, the pulling speed is appropriately reduced to allow the ingot to solidify slowly and avoid internal defects such as shrinkage cavities and porosity. When the cooling water volume is small, the pulling speed is appropriately increased to ensure production efficiency while maintaining the quality of the ingot. This achieves the goal of obtaining ingots with uniform microstructure and good quality, providing high-quality billets for subsequent hot rolling and ensuring that high-antimagnetic stainless steel can exhibit good performance during subsequent processing.

[0039] S5, hot rolling: the steel billet is heated in a zoned progressive manner, and after high-pressure descaling, rough rolling and finish rolling are carried out. After laminar cooling, it is coiled to obtain a hot-rolled black coil; the heating temperature in S5 is 1090-1110°C, the heating time is 40-80 minutes, the number of hot rolling deformation passes is 9-11, and the deformation of each pass is 8.5-9.5%.

[0040] Specifically, the steel slabs are heated in a zoned progressive manner. After high-pressure descaling, they are subjected to rough and finish rolling. After laminar cooling, they are coiled to obtain hot-rolled black coils. During the heating stage, the slabs are heated to 1090-1110°C for 40-80 minutes. During zoned progressive heating, the heating furnace is divided into 5-8 temperature control zones. Based on the surface temperature data of the slab fed back by high-precision temperature sensors and infrared thermal imagers, the central control system dynamically adjusts the heating power according to the heat conduction model. In the initial stage, the slabs are slowly heated to 1090°C at a heating rate of 5-8°C / min. The heating time in this stage is approximately 20-30 minutes. The purpose is to ensure uniform heating of the entire slab and reduce stress caused by internal temperature differences.

[0041] Then, induction heating is used to assist in heating. The induction heating frequency is 200-400kHz and the power is 500-1000kW. The temperature is quickly raised to 1110℃ within 10-20 minutes, so that the steel billet reaches a temperature suitable for hot rolling. Subsequently, hot rolling with a small deformation amount is carried out. The number of passes is set to 9-11 passes, and the deformation of each pass is strictly controlled at 8.5-9.5%. During the hot rolling process, with the help of pressure sensors, temperature sensors and displacement sensors installed on the rolling mill, the rolling force, rolled piece temperature and rolled thickness data are collected in real time. According to these data, the rolling speed, reduction and tension are dynamically adjusted, thereby achieving the refinement of the ingot grains, improving the organizational structure of the steel, and improving its comprehensive mechanical properties such as strength, toughness and plasticity, ensuring that the high antimagnetic stainless steel can meet various performance requirements in subsequent processing and use.

[0042] S6, solution pickling: The hot-rolled black coil is solution treated, and after shot blasting and scale breaking, it enters the pickling treatment to obtain a hot-rolled white coil; the solution treatment in S6 is to heat up to the solution temperature of 1070-1085℃ at a rate of 13-17℃ / s, and the insulation time is 1.6-1.9 minutes per millimeter thickness, and then air cooling, mist cooling and water cooling are used in sequence, with a cooling rate of 105-115℃ / s.

[0043] Specifically, the hot-rolled black coil is subjected to solution treatment, shot blasting and scale breaking treatment, and then enters the pickling treatment to obtain the hot-rolled white coil. During the solution treatment, high-speed induction heating equipment is used to rapidly heat the temperature to a solution temperature of 1070-1085°C at a speed of 13-17°C / s. High-speed induction heating uses the principle of electromagnetic induction to generate an induced current inside the cold-rolled steel, thereby rapidly heating it, thereby effectively reducing the residence time of the steel in the high temperature stage and reducing the risk of grain growth.

[0044] During the insulation stage, the standard of 1.6-1.9 minutes of insulation per millimeter of thickness is followed. For example, for 5 mm thick steel, the insulation time is 8-9.5 minutes. During the insulation process, the microstructure of the steel is observed in situ every 10-15 minutes with the help of a scanning transmission electron microscope (STEM), and the dissolution of the alloy elements is monitored in real time. If it is found that the alloy elements are not fully dissolved, the insulation time can be appropriately extended by 10-20 minutes or the temperature can be fine-tuned by 5-10°C to ensure that the alloy elements are fully integrated into the matrix to form a uniform solid solution.

[0045] After the insulation is completed, air cooling, mist cooling and water cooling are used to cool the steel to a cooling rate of 105-115℃ / s. Rapid cooling can fix the solid solution state at high temperature, avoid the re-precipitation and aggregation of alloy elements during the cooling process, and ensure the structural stability and performance consistency of the steel. This eliminates the work hardening and residual stress generated during the cold rolling process, makes the alloy elements evenly distributed in the matrix, optimizes the microstructure of the steel, and significantly improves the comprehensive performance of high antimagnetic stainless steel such as strength, toughness, and corrosion resistance to meet the needs of various stringent industrial applications.

[0046] S7, cold rolling: hot rolled white coil is rolled by continuous rolling mill / 20-high single rolling mill to obtain chilled coil, which is subjected to surface degreasing and solution treatment, electrolysis and pickling treatment, and online leveling and straightening treatment to obtain cold rolled 2B surface steel coil; the total deformation of cold rolling in S7 is 57-63%, and professional degreasing agent is used for surface degreasing. The conductivity of degreasing liquid is controlled at 6-9ms / cm and the temperature is controlled at 65-75℃. The solution treatment is 1 The temperature is raised to the solution temperature of 1070-1095°C at a rate of 3-17°C / s, and the insulation time is 1.6-1.9 minutes per millimeter of thickness. Then, air cooling, mist cooling and water cooling are used in sequence, with a cooling rate of 105-115°C / s. The electrolysis current is controlled at 3800-4200A and the temperature is controlled at 68-72°C. The flattening elongation is greater than 0.30%, and the tensile elongation is greater than 0.32%.

[0047] Specifically, the hot-rolled white coil is rolled on a continuous rolling mill / 20-high single rolling mill to obtain a chilled coil. After surface degreasing and solution treatment, it enters electrolysis and pickling treatment, and after online leveling and tension leveling treatment, it obtains a cold-rolled 2B surface steel coil. The steel is first passed through an induction heating device at a speed of 1-1.5m / min. The frequency of the induction heating device is 10-20kHz and the power is 200-300kW. The steel is heated to 720-780℃ within 5-7 minutes and kept warm for 2-3 minutes. The thermal activation of atoms is used to eliminate the work hardening generated during the hot rolling process. The plasticity of the steel is restored, and then it is quickly cooled to room temperature using aerosol cooling. Compressed air and cooling water are mixed and atomized and then sprayed onto the steel surface. The cooling rate reaches 50-80℃ / s to fix the restored structure. It is then placed in an electrolyte containing phosphoric acid, sulfuric acid (volume ratio 3:1-4:1) and additives (corrosion inhibitors, brighteners, etc.), a DC voltage of 2-3V is applied, and electrochemical polishing is performed for 10-15 minutes to remove tiny defects and oxide films on the steel surface, reduce the surface roughness to Ra0.2-0.3μm, and improve the surface quality.

[0048] The steel is then rolled in a tandem mill / 20-high single-mill. Based on the material properties and target thickness, the pressure distribution of each stand is optimized to maintain a total deformation of 57-63%. The reduction distribution for each stand is roughly: 15%-19% for the first stand, 13%-15% for the second stand, 10%-12% for the third stand, 8%-10% for the fourth stand, 7%-8% for the fifth stand, and 4%-5% for the sixth stand. During this process, a lubricant containing nano-additives (nano-titanium dioxide and nano-zinc oxide composite particles with a particle size of 20-50nm, added at a level of 0.5%-1% of the total lubricant) is uniformly dispersed throughout the lubricant through a special dispersion process. This forms a nano-scale lubricating protective film on the steel surface, reducing the friction coefficient by 40-50% and effectively minimizing surface scratches and cracks. This improves the steel's surface quality while precisely controlling its dimensional accuracy, further refining the grain size, and increasing its strength and hardness, ultimately resulting in the production of high-quality, anti-magnetic stainless steel.

[0049] The following is further introduced in conjunction with specific embodiments:

[0050] Example 1:

[0051] A high-antimagnetic stainless steel comprises the following raw materials in percentages: 0.03% carbon, 0.3% silicon, 12.3% manganese, 0.04% phosphorus, 0.03% sulfur, 14% nickel, 20% chromium, 1% copper, 0.2% nitrogen, 2% titanium, 3% niobium and 3% molybdenum, with the remainder being iron.

[0052] A method for preparing high antimagnetic stainless steel comprises the following steps:

[0053] S1. Raw material preparation: take the raw materials according to percentage and pre-process them;

[0054] S2. Melting: adding the pretreated raw materials into an electric arc furnace for melting to obtain a raw material solution;

[0055] S3, refining: using argon oxygen decarburization process to refine the raw material solution to obtain molten steel;

[0056] S4, casting: casting the molten steel into the continuous casting machine, and controlling the solidification process of the ingot by adjusting the cooling water volume and casting speed to obtain a steel ingot;

[0057] S5, hot rolling: the steel billet is heated gradually in different zones, and after high pressure descaling, rough rolling and finish rolling are carried out. After laminar cooling, the steel billet is coiled to obtain hot rolled black coil;

[0058] S6, solution pickling: the hot-rolled black coil is subjected to solution treatment, shot blasting and scale breaking, and then enters pickling treatment to obtain the hot-rolled white coil;

[0059] S7. Cold rolling: The hot-rolled white coil is rolled on a continuous rolling mill / a twenty-high single rolling mill to obtain a chilled coil. After surface degreasing and solution treatment, it enters electrolysis and pickling treatment, and after online leveling and straightening treatment, it obtains a cold-rolled 2B surface steel coil.

[0060] The pretreatment in S1 includes crushing the bulk raw materials to a particle size of 6-9 mm.

[0061] The smelting temperature in S2 is 1520-1630°C and the smelting time is 70-110 minutes.

[0062] The refining temperature in S3 is 1510-1540°C, and the refining time is 35-55 minutes.

[0063] In S4, the casting speed of the molten steel into the continuous casting machine is 0.9-1.4m / min, and the cooling water volume is 6-14m 3 / h, and the pulling speed is 0.9-1.1m / min.

[0064] The heating temperature in S5 is 1090-1110° C., the heating time is 40-80 minutes, the number of hot rolling deformation passes is 9-11, and the deformation amount of each pass is 8.5-9.5%.

[0065] The solution treatment in S6 is to heat up to the solution temperature of 1070-1085°C at a rate of 13-17°C / s, and keep warm for 1.6-1.9 minutes per millimeter of thickness. Then, air cooling, mist cooling and water cooling are used in sequence, and the cooling rate is 105-115°C / s.

[0066] The solution treatment in S6 is to heat up to the solution temperature of 1070-1085°C at a rate of 13-17°C / s, and keep warm for 1.6-1.9 minutes per millimeter of thickness. Then, air cooling, mist cooling and water cooling are used in sequence, and the cooling rate is 105-115°C / s.

[0067] Example 2:

[0068] This embodiment differs from the above-mentioned embodiment 1 in that:

[0069] A high-antimagnetic stainless steel includes the following percentages of raw materials: 0.02% carbon, 0.25% silicon, 11.9% manganese, 0.04% phosphorus, 0.03% sulfur, 12% nickel, 19% chromium, 0.55% copper, 0.175% nitrogen, 1.5% titanium, 2% niobium, 2.5% molybdenum, and the remainder is iron.

[0070] Example 3:

[0071] This embodiment differs from the above-mentioned embodiment 1 in that:

[0072] A high-antimagnetic stainless steel comprises the following raw materials in percentages: 0.01% carbon, 0.2% silicon, 11.5% manganese, 0.04% phosphorus, 0.03% sulfur, 10% nickel, 18.0% chromium, 0.1% copper, 0.15% nitrogen, 1% titanium, 1% niobium, 2% molybdenum, and the remainder being iron.

[0073] Table 1:

[0074] contrast Example 1 Example 2 Example 3 Standard value Yield strength (MPa) 507 472 463 205 Tensile strength (MPa) 809 745 711 520 Elongation (%) 63 51 47 40 Hardness (HBW) 246 218 197 180

[0075] The above table compares traditional high-antimagnetic stainless steel. Table 1 shows that different amounts of carbon, silicon, manganese, phosphorus, sulfur, nickel, chromium, copper, nitrogen, titanium, niobium, molybdenum, and iron can affect the structure and performance of stainless steel. Through the mutual cooperation of these elements, a stable austenite structure is constructed, the influence of carbides is reduced, and the grain size is refined. This solves the problem that although traditional stainless steel is non-magnetic in itself, it will produce obvious magnetism after deep drawing, causing this type of material to fail magnetic inspections in various transportation vehicles and supermarkets.

[0076] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A high antimagnetic stainless steel, characterized in that: The raw materials include the following percentages: carbon 0.01%-0.03%, silicon 0.2%-0.3%, manganese 11.5%-12.3%, phosphorus ≤0.04%, sulfur ≤0.03%, nickel 10%-14%, chromium 18.0%-20%, copper 0.1%-1%, nitrogen 0.15%-0.2%, titanium 1%-2%, niobium 1%-3% and molybdenum 2%-3%, and the rest is iron.

2. A method for preparing high antimagnetic stainless steel, characterized by: The high antimagnetic stainless steel according to claim 1 comprises the following steps: S1. Raw material preparation: take the raw materials according to percentage and pre-process them; S2. Melting: adding the pretreated raw materials into an electric arc furnace for melting to obtain a raw material solution; S3, refining: using argon oxygen decarburization process to refine the raw material solution to obtain molten steel; S4, casting: casting the molten steel into the continuous casting machine, and controlling the solidification process of the ingot by adjusting the cooling water volume and casting speed to obtain a steel ingot; S5, hot rolling: the steel billet is heated gradually in different zones, and after high pressure descaling, rough rolling and finish rolling are carried out. After laminar cooling, the steel billet is coiled to obtain hot rolled black coil; S6, solution pickling: the hot-rolled black coil is subjected to solution treatment, shot blasting and scale breaking, and then enters pickling treatment to obtain the hot-rolled white coil; S7. Cold rolling: The hot-rolled white coil is rolled on a continuous rolling mill / a twenty-high single rolling mill to obtain a chilled coil. After surface degreasing and solution treatment, it enters electrolysis and pickling treatment, and after online leveling and straightening treatment, it obtains a cold-rolled 2B surface steel coil.

3. The method for preparing high antimagnetic stainless steel according to claim 2, characterized in that: The pretreatment in S1 includes crushing the bulk raw materials to a particle size of 6-9 mm.

4. The method for preparing high antimagnetic stainless steel according to claim 2, characterized in that: The smelting temperature in S2 is 1520-1630° C. and the smelting time is 70-110 minutes.

5. The method for preparing high antimagnetic stainless steel according to claim 2, characterized in that: The refining temperature in S3 is 1510-1540° C., and the refining time is 35-55 minutes.

6. The method for preparing high antimagnetic stainless steel according to claim 2, characterized in that: The casting speed of the molten steel into the continuous casting machine in S4 is 0.9-1.4m / min, and the cooling water volume is 6-14m 3 / h, and the pulling speed is 0.9-1.1m / min.

7. The method for preparing high antimagnetic stainless steel according to claim 2, characterized in that: The heating temperature in S5 is 1090-1110° C., the heating time is 40-80 minutes, the number of hot rolling deformation passes is 9-11, and the deformation amount of each pass is 8.5-9.5%.

8. The method for preparing high antimagnetic stainless steel according to claim 2, characterized in that: The solution treatment in S6 is to heat up to the solution temperature of 1070-1085°C at a rate of 13-17°C / s, and keep warm for 1.6-1.9 minutes per millimeter of thickness, and then cool in sequence by air cooling, mist cooling and water cooling, with a cooling rate of 105-115°C / s.

9. The method for preparing high antimagnetic stainless steel according to claim 2, characterized in that: The total deformation of the cold rolling in S7 is 57-63%, the surface degreasing uses a professional degreasing agent, the conductivity of the degreasing liquid is controlled at 6-9ms / cm, and the temperature is controlled at 65-75°C. The solution treatment is to heat the temperature to the solution temperature of 1070-1095°C at a rate of 13-17°C / s, and the insulation time is 1.6-1.9 minutes per millimeter of thickness. Then, air cooling, mist cooling, and water cooling are used in sequence for cooling, and the cooling rate is 105-115°C / s. The current of the electrolysis is controlled at 3800-4200A and the temperature is controlled at 68-72°C. The flattening elongation is greater than 0.30%, and the elongation of the tension leveling is greater than 0.32%.

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