Low-copper stainless steel formula and preparation method thereof

Abstract

The invention relates to the field of stainless steel, and discloses a low-copper stainless steel formula and a preparation method thereof.The low-copper stainless steel formula comprises, by weight, 0.08%-0.13% of carbon, 0.2%-0.3% of silicon, 11.5%-12.3% of manganese, smaller than or equal to 0.04% of phosphorus, smaller than or equal to 0.03% of sulfur, 1.0%-1.3% of nickel, 13.0%-13.2% of chromium, 0.1%-1% of copper, 0.15%-0.2% of nitrogen and the balance iron. By partially replacing nickel with manganese, on the premise of ensuring the basic performance of the stainless steel, the use amount of expensive nickel element is reduced, so that the production cost is reduced, the competitiveness of the product in a price-sensitive market is improved, and the application range of the low-copper stainless steel is expanded; stainless steel materials with excellent performance can be used in more industries with strict cost control.

Description

Technical Field

[0001] The invention relates to the technical field of stainless steel, in particular to a low-copper stainless steel formula and a preparation method thereof. Background Art

[0002] In the modern industrial field, stainless steel, as an important metal material, is widely used in many industries such as construction, machinery manufacturing, chemical industry, and food processing. With its excellent corrosion resistance, high strength, and good processing performance, it meets the strict requirements for material performance in different scenarios. With the continuous advancement of industrial technology and the increasing diversification of market demand, the requirements for stainless steel performance are becoming more and more stringent. It is not only necessary to maintain stable performance under conventional conditions, but also to show excellent adaptability under complex and harsh working conditions.

[0003] Traditional stainless steel formulas, such as 304 stainless steel, use a large amount of nickel. Due to the high price of nickel, the production cost of stainless steel remains high, limiting its application in some cost-sensitive fields. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a low-copper stainless steel formula and a preparation method thereof, which solves the problem that traditional stainless steel formulas use a large amount of nickel elements. Due to the high price of nickel, the production cost of stainless steel remains high, which limits its application in some cost-sensitive fields.

[0005] To achieve the above objectives, the present invention is implemented through the following technical scheme: a low-copper stainless steel formula, including the following percentage raw materials: carbon 0.08%-0.13%, silicon 0.2%-0.3%, manganese 11.5%-12.3%, phosphorus ≤0.04%, sulfur ≤0.03%, nickel 1.0%-1.3%, chromium 13.0%-13.2%, copper 0.1%-1%, nitrogen 0.15%-0.2%, and the rest is iron.

[0006] A method for preparing low-copper stainless steel comprises the following steps:

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

[0008] S2, smelting: adding the pretreated raw materials into an electric arc furnace in sequence for smelting 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 the casting speed to obtain a steel ingot;

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

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

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

[0014] Preferably, the pretreatment in S1 includes crushing the bulk raw material to a particle size of 5-10 mm.

[0015] Preferably, the smelting temperature in S2 is 1500-1650° C. and the smelting time is 60-120 minutes.

[0016] Preferably, the refining temperature in S3 is 1500-1550° C., and the refining time is 30-60 minutes.

[0017] Preferably, the casting speed of casting the molten steel into the continuous casting machine in S4 is 0.8-1.5 m / min, and the cooling water volume is 5-15 m 3 / h, and the pulling speed is 0.8-1.2m / min.

[0018] Preferably, the heating temperature in S5 is 1080-1120° C., the heating time is 30-90 minutes, the number of hot rolling deformation passes is 8-12 passes, and the deformation amount of each pass is 8-10%.

[0019] Preferably, the solution treatment in S6 is to heat up to the solution temperature of 1060-1090°C at a rate of 12-18°C / s, and keep warm for 1.5-2 minutes per millimeter thickness, and then cool in sequence by air cooling, mist cooling and water cooling, with a cooling rate of 100-120°C / s.

[0020] Preferably, the total deformation of cold rolling in S7 is 55-65%, the surface degreasing adopts a professional degreasing agent, the conductivity of the degreasing liquid is controlled at 5-10ms / cm, and the temperature is controlled at 60-80°C, the solution treatment is heated to the solution temperature of 1060-1100°C at a rate of 12-18°C / s, the insulation time is 1.5-2 minutes per millimeter thickness, and then air cooling, mist cooling, and water cooling are used in turn for cooling, and the cooling rate is 100-120°C / s, the electrolysis current is controlled at 3500-4500A, and the temperature is controlled at 65-75°C, the flattening elongation is greater than 0.28%, and the elongation of the tension straightening is greater than 0.3%.

[0021] The present invention provides a low-copper stainless steel formula and a preparation method thereof, which has the following beneficial effects:

[0022] 1. The present invention partially replaces nickel with manganese, thereby reducing the use of expensive nickel elements while ensuring the basic properties of stainless steel, thereby reducing production costs, improving the competitiveness of products in price-sensitive markets, and expanding the application scope of low-copper stainless steel, allowing more industries with strict cost control to use stainless steel materials with excellent performance, thereby solving the problem that traditional stainless steel formulas use a large amount of nickel elements, and the high price of nickel leads to high stainless steel production costs, limiting its application in some cost-sensitive fields.

[0023] 2. The present invention enhances the corrosion resistance of stainless steel through the synergistic effect of elements such as chromium, nickel, copper, and nitrogen. The dense oxide film formed by chromium is the basis of corrosion resistance, nickel expands the austenite phase region and assists in improving corrosion resistance, copper further improves corrosion resistance and stress corrosion resistance, and nitrogen also makes a positive contribution to corrosion resistance, so that the low-copper stainless steel can be used stably for a long time in a variety of corrosive environments, thereby extending the service life of the product.

[0024] 3. The present invention improves strength and hardness through carbon, enhances strength and oxidation resistance through silicon, and reduces the harmful effects of sulfur and improves mechanical properties through manganese. At the same time, the phosphorus and sulfur content are strictly controlled to avoid excessive damage to toughness and welding performance, so that stainless steel can maintain stable performance under different processing and use conditions.

[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 organizational structure, hot rolling refines grains and improves organizational 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 organizational structure and excellent comprehensive performance. While ensuring strength and hardness, it significantly improves corrosion resistance, stress corrosion resistance, etc., optimizes processing performance, and reduces production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention provides a method flow chart for preparing low-copper stainless steel. DETAILED DESCRIPTION

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

[0028] Please see attached Figure 1 The embodiment of the present invention provides a low-copper stainless steel formula, including the following percentage raw materials: carbon 0.08%-0.13%, silicon 0.2%-0.3%, manganese 11.5%-12.3%, phosphorus ≤0.04%, sulfur ≤0.03%, nickel 1.0%-1.3%, chromium 13.0%-13.2%, copper 0.1%-1%, nitrogen 0.15%-0.2%, and the rest is iron.

[0029] Specifically, by adding carbon, it forms an interstitial solid solution with iron, thereby improving the strength and hardness of the steel, while affecting the toughness and corrosion resistance of the steel to a certain extent; thus, it is possible to balance other properties while meeting certain strength requirements, so that low-copper stainless steel can adapt to a variety of application scenarios. However, too high a carbon content will reduce corrosion resistance, so it is controlled within the range of 0.08%-0.13%.

[0030] By adding silicon, silicon is dissolved in ferrite, thereby improving the strength and hardness of the steel and enhancing the steel's oxidation resistance; thereby achieving the improvement of the stability of low-copper stainless steel in high temperature environments and ensuring its performance under different working conditions.

[0031] By adding manganese, nickel can be partially replaced, thereby reducing production costs. At the same time, manganese and sulfur form manganese sulfide, which reduces the harmful effects of sulfur and improves the strength and toughness of steel. This achieves the maintenance and optimization of the comprehensive mechanical properties of low-copper stainless steel while controlling costs.

[0032] By adding phosphorus, it is dissolved in ferrite, thereby improving the strength and hardness of the steel. Under the condition of reasonably controlling its content (≤0.04%), its strengthening effect is utilized while avoiding excessive negative impact on other key properties.

[0033] The addition of sulfur will form sulfide inclusions in the steel, thereby reducing the toughness, plasticity and corrosion resistance of the steel; but to a certain extent, it can improve the cutting performance of the steel. In low-copper stainless steel, the sulfur content is strictly controlled to ≤0.03%, while obtaining limited cutting performance improvement and reducing its damage to other properties.

[0034] By adding nickel, the austenite phase area is expanded, so that the stainless steel can maintain the austenite structure at room temperature, and the toughness, ductility and corrosion resistance of the steel are improved; thereby improving the comprehensive performance of low-copper stainless steel, so that it can maintain a good working condition in various environments.

[0035] By adding chromium, a dense chromium oxide film is formed on the surface of the steel, which prevents further oxidation and corrosion of the internal metal. It is the main element that determines the corrosion resistance of stainless steel. It gives low-copper stainless steel excellent corrosion resistance and meets its use requirements in different corrosive environments.

[0036] By adding copper, it works synergistically with other elements in low-copper stainless steel to improve the strength, corrosion resistance and stress corrosion resistance of the steel; thereby further optimizing the performance of low-copper stainless steel in specific environments, such as being able to work stably in some environments with stress corrosion risks.

[0037] By adding nitrogen, it is dissolved in austenite, thereby increasing the strength and hardness of the steel, while also improving the corrosion resistance of the steel; thereby achieving the goal of improving the mechanical properties of low-copper stainless steel without reducing its corrosion resistance, thereby improving its overall performance.

[0038] The addition of iron serves as the matrix of stainless steel, providing a load-bearing basis for other alloy elements and determining the basic physical and mechanical properties of stainless steel; thereby achieving the basic framework of low-copper stainless steel, allowing other elements to play their respective roles and form alloy materials with specific properties.

[0039] Through the cooperation of various raw materials, a complex and stable alloy system is formed. Each element works synergistically to give full play to its own advantages and make up for each other's shortcomings. Elements such as carbon, silicon, and manganese cooperate with each other in improving strength and hardness, and enhance the overall mechanical properties without affecting other key properties; nickel, chromium, copper, nitrogen and other elements work together to improve corrosion resistance, building a more stable corrosion resistance mechanism, thereby achieving a good balance between mechanical properties and corrosion resistance of low-copper stainless steel, so that it has both high strength and hardness, can withstand large external forces, and has excellent corrosion resistance, and can adapt to a variety of complex use environments. At the same time, by precisely controlling the content of each element, it also optimizes processing performance and reduces production costs, thus solving the problem that traditional stainless steel formulas use a large amount of nickel elements. Due to the high price of nickel, the production cost of stainless steel remains high, which limits its application in some cost-sensitive fields.

[0040] A method for preparing low-copper stainless steel comprises the following steps:

[0041] 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 5-10 mm.

[0042] Specifically, by taking the raw materials according to percentages and pre-treating them, it is ensured that the elements can be evenly distributed in the subsequent processing process, avoiding uneven composition due to differences in raw material particle size and impurities. The block raw materials are crushed to a particle size of 5-10mm, which is conducive to rapid melting during smelting and can ensure full contact with other raw materials during the mixing process, thereby improving the uniformity of mixing. For easily oxidized raw materials, the surface is cleaned to remove the oxide layer to prevent oxidized impurities from mixing into the molten steel during the smelting process, affecting the purity and composition accuracy of the molten steel. This provides high-quality, precise and uniform raw materials for the subsequent smelting process, laying a solid foundation for the preparation of low-copper stainless steel with stable performance and meeting the requirements.

[0043] S2, smelting: the pretreated raw materials are sequentially added into an electric arc furnace for smelting to obtain a raw material solution; the smelting temperature in S2 is 1500-1650°C and the smelting time is 60-120 minutes.

[0044] Specifically, the raw materials after pretreatment are added to the electric arc furnace for smelting in sequence to obtain a raw material solution, so that various raw materials are fully fused under high temperature environment. In a specific order, most of the iron materials are added first to build a basic framework for the alloy system, and then alloy materials such as ferromanganese and ferrochrome are added to gradually dissolve and diffuse. Finally, precious alloy elements such as nickel and copper are added to ensure that they are evenly distributed. At high temperatures of 1500-1650℃, the activity of atoms is enhanced, which accelerates the diffusion and fusion between elements. The smelting time is controlled at 60-120 minutes to ensure the full progress of the reaction. Through the precise control of temperature and time, the raw materials are evenly mixed at the atomic level, so as to obtain a raw material solution with uniform composition and in line with the requirements of the low-copper stainless steel formula, which provides good initial materials for the subsequent refining process to remove impurities and accurately adjust the composition, and ensures that the low-copper stainless steel finally prepared has stable and excellent performance.

[0045] S3, refining: the raw material solution is refined by argon oxygen decarburization process to obtain molten steel; the refining temperature in S3 is 1500-1550°C, and the refining time is 30-60 minutes.

[0046] Specifically, the raw material solution is refined by using the argon oxygen decarburization process to obtain molten steel, thereby utilizing the synergistic effect of oxygen and argon to effectively remove carbon and other impurities in the raw material solution. In the initial stage of refining, the flow ratio of oxygen to argon is controlled at 3:1-4:1. The high oxygen content promotes the rapid oxidation of carbon to generate carbon monoxide and other gases for discharge, thereby achieving rapid decarburization. As the refining progresses, when the carbon content in the molten steel drops to 0.1%-0.15%, the flow ratio of oxygen to argon is adjusted to 2:1-3:1 to prevent excessive oxidation of other alloying elements. At a refining temperature of 1500-1550°C, the chemical reaction rate is effectively guaranteed, while avoiding the adverse effects of excessively high temperatures on equipment and alloying elements. The refining time is controlled at 30-60 minutes to ensure that the decarburization and impurity removal reactions are fully carried out. Through precise control of temperature, time and gas flow ratio, the carbon content in the molten steel can be reduced, harmful impurities such as sulfur and phosphorus can be removed, the purity of the molten steel can be improved, and molten steel with precise composition and high purity can be provided for subsequent casting and other processes, creating favorable conditions for the preparation of high-performance low-copper stainless steel.

[0047] 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; in S4, the casting speed of casting the molten steel into the continuous casting machine is 0.8-1.5m / min, and the cooling water volume is 5-15m 3 / h, and the pulling speed is 0.8-1.2m / min.

[0048] Specifically, the mold of the continuous casting machine is preheated at 150-200℃ for 2-4 hours to reduce the temperature difference between the mold and the molten steel, prevent the molten steel from generating excessive thermal stress due to sudden cooling at the initial stage of casting, and reduce 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 0.8-1.5m / 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 5-15m / min. 3 / h of cooling water and 0.8-1.2m / min of pulling speed are used to coordinately control the solidification process of the ingot. The amount of cooling water determines the solidification rate of the molten steel, and the pulling speed matches the cooling rate to ensure that the ingot maintains a uniform organizational structure during the solidification process. When the amount of cooling water is large, the pulling speed is appropriately reduced to allow the ingot to solidify slowly and avoid internal defects such as shrinkage cavities and looseness; when the amount of cooling water is small, the pulling speed is appropriately increased to ensure production efficiency while maintaining the quality of the ingot, thereby achieving a uniform organizational structure and good quality ingot, providing high-quality billets for subsequent hot rolling, and ensuring that low-copper stainless steel can exhibit good performance during subsequent processing.

[0049] S5, hot rolling: the steel billet is heated progressively in different zones, rough rolled and finish rolled after high pressure descaling, and coiled after laminar cooling to obtain hot rolled black coil; the heating temperature in S5 is 1080-1120°C, the heating time is 30-90 minutes, the number of hot rolling deformation passes is 8-12, and the deformation amount of each pass is 8-10%.

[0050] Specifically, the steel billet is heated progressively in different zones, rough rolled and finished rolled after high pressure descaling, and coiled after laminar cooling to obtain hot rolled black coil. In the heating stage, the billet is heated to 850-1120℃ for 30-90 minutes. During the progressive heating in different zones, the heating furnace is divided into 5-8 temperature control zones. Each zone is based on the billet surface temperature data fed back by the high-precision temperature sensor and infrared thermal imager. The central control system dynamically adjusts the heating power according to the heat conduction model. In the initial stage, the billet is slowly heated to 850-900℃ at a heating rate of 5-8℃ / min. The heating time in this stage is about 20-30 minutes. The purpose is to heat the billet evenly as a whole and reduce the stress caused by the internal temperature difference.

[0051] 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 1080-1120℃ within 10-20 minutes, so that the billet reaches a temperature suitable for hot rolling. Subsequently, small deformation hot rolling is carried out, and the number of passes is set to 8-12 passes. The deformation of each pass is strictly controlled at 8-10%. 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. The rolling speed, reduction and tension are dynamically adjusted based on these data, 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 low-copper stainless steel can meet various performance requirements in subsequent processing and use.

[0052] S6, solution pickling: the hot-rolled black coil is subjected to solution treatment, and then to pickling after shot blasting and scale breaking to obtain a hot-rolled white coil; the solution treatment in S6 is to heat the temperature to the solution temperature of 1060-1090°C at a rate of 12-18°C / s, and the insulation time is 1.5-2 minutes per millimeter thickness, and then air cooling, mist cooling and water cooling are used in turn for cooling, and the cooling rate is 100-120°C / s.

[0053] Specifically, the hot-rolled black coil is solution treated, shot blasted and scaled, and then pickled to obtain the hot-rolled white coil. During the solution treatment, high-speed induction heating equipment is used to quickly heat the temperature to 1060-1090°C at a speed of 12-18°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 up, thereby effectively reducing the residence time of the steel in the high temperature stage and reducing the risk of grain growth.

[0054] During the insulation stage, the standard of 1.5-2 minutes of insulation is followed for every millimeter of thickness. For example, for 5 mm thick steel, the insulation time is 7.5-10 minutes. During the insulation process, the microstructure of the steel is observed in situ every 10-15 minutes using 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.

[0055] After the insulation is completed, air cooling, mist cooling and water cooling are used to cool the steel to a cooling rate of 100-120℃ / 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 organizational stability and performance consistency of the steel. This eliminates the work hardening and residual stress generated during the cold rolling process, evenly distributes the alloy elements in the matrix, optimizes the microstructure of the steel, and significantly improves the comprehensive performance of low-copper stainless steel such as strength, toughness, and corrosion resistance to meet various stringent industrial application requirements.

[0056] S7, cold rolling: hot rolled white coils are rolled by continuous rolling mill / 20-high single rolling mill to obtain cold hard coils, which are subjected to surface degreasing and solution treatment, electrolysis and pickling treatment, and online leveling and straightening treatment to obtain cold rolled 2B surface steel coils; the total deformation of cold rolling in S7 is 55-65%, and professional degreasing agent is used for surface degreasing. The conductivity of the degreasing liquid is controlled at 5-10ms / cm and the temperature is controlled at 60-80℃. The solution treatment is The temperature is raised to the solution temperature of 1060-1100°C at a rate of 12-18°C / s, and the insulation time is 1.5-2 minutes per millimeter thickness. Then, air cooling, mist cooling and water cooling are used in sequence, and the cooling rate is 100-120°C / s. The electrolysis current is controlled at 3500-4500A and the temperature is controlled at 65-75°C. The flattening elongation is greater than 0.28%, and the elongation of tension straightening is greater than 0.3%.

[0057] Specifically, the hot-rolled white coil is rolled by a continuous rolling mill / a twenty-high single rolling mill to obtain a cold hard coil. After surface degreasing and solution treatment, it enters electrolysis and pickling treatment, and after online leveling and tension straightening treatment, a cold-rolled 2B surface steel coil is obtained. 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 by 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 organizational structure. Then it is 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.

[0058] Then, the rolling mill / 20-high single rolling mill is used. According to the material characteristics and target thickness, the reduction distribution of each stand is optimized to control the total deformation at 55-65%. The reduction distribution of each stand is roughly as follows: 15%-20% for the first stand, 12%-15% for the second stand, 10%-12% for the third stand, 8%-10% for the fourth stand, 6%-8% for the fifth stand, and 4%-6% for the sixth stand. In this process, a lubricant containing nano additives (nano titanium dioxide and nano zinc oxide composite particles, with a particle size between 20-50nm, and an addition amount of 0.5%-1% of the total amount of lubricant) is used, which is evenly dispersed in the lubricant through a special dispersion process to form a nano-level lubricating protective film on the surface of the steel, reducing the friction coefficient by 40-50%, effectively reducing the generation of surface scratches and cracks, thereby achieving the improvement of the surface quality of the steel while accurately controlling the dimensional accuracy of the steel, further refining the grains, improving the strength and hardness of the steel, and completing the high-quality preparation of low-copper stainless steel.

[0059] The following is further introduced in conjunction with specific embodiments:

[0060] Embodiment 1:

[0061] A low-copper stainless steel formula includes the following percentage raw materials: carbon 0.13%, silicon 0.3%, manganese 12.3%, phosphorus ≤ 0.04%, sulfur ≤ 0.03%, nickel 1.3%, chromium 13.2%, copper 1%, nitrogen 0.2%, and the rest is iron.

[0062] A method for preparing low-copper stainless steel comprises the following steps:

[0063] S1. Raw material preparation: take the raw materials according to percentage and pre-treat them;

[0064] S2, smelting: adding the pretreated raw materials into an electric arc furnace in sequence for smelting to obtain a raw material solution;

[0065] S3, refining: using argon oxygen decarburization process to refine the raw material solution to obtain molten steel;

[0066] 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 casting speed to obtain a steel ingot;

[0067] S5, hot rolling: the steel billet is heated gradually in different zones, rough rolled and finished rolled after high pressure descaling, and coiled after laminar cooling to obtain hot rolled black coil;

[0068] S6, solution pickling: the hot-rolled black coil is subjected to solution treatment, and then to pickling treatment after shot blasting and descaling to obtain a hot-rolled white coil;

[0069] S7. Cold rolling: The hot-rolled white coil is rolled by a continuous rolling mill / a twenty-high single rolling mill to obtain a cold hard coil. After surface degreasing and solution treatment, it enters electrolysis and pickling treatment, and after online leveling and straightening treatment, a cold-rolled 2B surface steel coil is obtained.

[0070] The pretreatment in S1 includes crushing the bulk raw materials to a particle size of 5-10 mm

[0071] The melting temperature in S2 is 1500-1650℃ and the melting time is 60-120 minutes

[0072] The refining temperature in S3 is 1500-1550℃ and the refining time is 30-60 minutes

[0073] In S4, the casting speed of the molten steel into the continuous casting machine is 0.8-1.5m / min, and the cooling water volume is 5-15m 3 / h, pulling speed is 0.8-1.2m / min

[0074] The heating temperature in S5 is 1080-1120°C, the heating time is 30-90 minutes, the hot rolling deformation is 8-12 times, and the deformation of each time is 8-10%.

[0075] In S6, the solution treatment is to heat up to the solution temperature of 1060-1090℃ at a rate of 12-18℃ / s, and the insulation time is 1.5-2 minutes per millimeter thickness, and then cool by air cooling, mist cooling, and water cooling in turn, with a cooling rate of 100-120℃ / s

[0076] The total deformation of cold rolling in S7 is 55-65%. Professional degreasing agent is used for surface degreasing. The conductivity of the degreasing liquid is controlled at 5-10ms / cm and the temperature is controlled at 60-80℃. The solution treatment is heated to the solution temperature of 1060-1100℃ at a rate of 12-18℃ / s. The insulation time is 1.5-2 minutes per millimeter thickness, and then air cooling, mist cooling and water cooling are used in turn. The cooling rate is 100-120℃ / s. The electrolysis current is controlled at 3500-4500A and the temperature is controlled at 65-75℃. The flat elongation is greater than 0.28%, and the elongation of tension straightening is greater than 0.3%.

[0077] Embodiment 2:

[0078] The difference between this embodiment and the above-mentioned embodiment 1 is that:

[0079] A low-copper stainless steel formula includes the following percentage raw materials: carbon 0.08%, silicon 0.2%, manganese 11.5%, phosphorus ≤0.04%, sulfur ≤0.03%, nickel 1.0%, chromium 13.0%, copper 0.1%, nitrogen 0.15%, and the rest is iron.

[0080] Embodiment 3:

[0081] The difference between this embodiment and the above-mentioned embodiment 1 is that:

[0082] A low-copper stainless steel formula includes the following percentage raw materials: carbon 0.1%, silicon 0.25%, manganese 11.9%, phosphorus ≤ 0.04%, sulfur ≤ 0.03%, nickel 1.15%, chromium 13.1%, copper 0.55%, nitrogen 0.175%, and the rest is iron.

[0083] Table 1:

[0084] contrast Example 1 Example 2 Example 3 Standard value Yield strength(MPa) 550 500 530 205 Tensile strength(MPa) 850 800 830 520 Hardness(HBW) 220 200 210 180

[0085] The above table compares the traditional low-copper stainless steel formula. It can be seen from Table 1 that different amounts of carbon, silicon, manganese, phosphorus, sulfur, nickel, chromium, copper, nitrogen, and iron can affect the organizational structure and performance of stainless steel, thereby synergizing from different angles such as strength, toughness, and corrosion resistance to enhance the comprehensive performance of stainless steel. The change in carbon content will affect the strength and hardness of stainless steel. An appropriate amount of carbon can improve the strength, silicon can enhance the strength and hardness of steel, and improve oxidation resistance. Manganese can improve the toughness and processing properties of steel, nickel can improve the toughness, corrosion resistance and low-temperature performance of stainless steel, copper can improve the corrosion resistance and strength of stainless steel, nitrogen can improve the strength and corrosion resistance of stainless steel, and partial replacement of nickel can also reduce costs. Therefore, under the premise of ensuring the comprehensive performance of stainless steel, the use of nickel is reduced, the production cost of stainless steel is reduced, and the problem of large-scale use of nickel in traditional stainless steel formulas is solved. Due to the high price of nickel, the production cost of stainless steel remains high, which limits its application in some cost-sensitive fields.

[0086] Although 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 the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A low copper stainless steel formula, characterized in that: The raw materials include the following percentages: carbon 0.08%-0.13%, silicon 0.2%-0.3%, manganese 11.5%-12.3%, phosphorus ≤0.04%, sulfur ≤0.03%, nickel 1.0%-1.3%, chromium 13.0%-13.2%, copper 0.1%-1%, nitrogen 0.15%-0.2%, and the rest is iron.

2. A method for preparing low-copper stainless steel, characterized in that: A low-copper stainless steel formulation as claimed in claim 1, comprising the following steps: S1. Raw material preparation: take the raw materials according to percentage and pre-treat them; S2, smelting: adding the pretreated raw materials into an electric arc furnace in sequence for smelting 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 the casting speed to obtain a steel ingot; S5, hot rolling: the steel billet is heated gradually in different zones, rough rolled and finished rolled after high pressure descaling, and coiled after laminar cooling to obtain hot rolled black coil; S6, solution pickling: the hot-rolled black coil is subjected to solution treatment, and then to pickling treatment after shot blasting and descaling to obtain a hot-rolled white coil; S7. Cold rolling: The hot-rolled white coil is rolled by a continuous rolling mill / a twenty-high single rolling mill to obtain a cold hard coil. After surface degreasing and solution treatment, it enters electrolysis and pickling treatment, and after online leveling and straightening treatment, a cold-rolled 2B surface steel coil is obtained.

3. A method for preparing low-copper stainless steel according to claim 2, characterized in that: The pretreatment in S1 includes crushing the bulk raw materials to a particle size of 5-10 mm.

4. A method for preparing low-copper stainless steel according to claim 2, characterized in that: The smelting temperature in S2 is 1500-1650° C. and the smelting time is 60-120 minutes.

5. A method for preparing low-copper stainless steel according to claim 2, characterized in that: The refining temperature in S3 is 1500-1550° C., and the refining time is 30-60 minutes.

6. A method for preparing low-copper stainless steel according to claim 2, characterized in that: The casting speed of the molten steel into the continuous casting machine in S4 is 0.8-1.5m / min, and the cooling water volume is 5-15m 3 / h, and the pulling speed is 0.8-1.2m / min.

7. A method for preparing low-copper stainless steel according to claim 2, characterized in that: The heating temperature in S5 is 1080-1120° C., the heating time is 30-90 minutes, the hot rolling deformation is 8-12 times, and the deformation of each time is 8-10%.

8. A method for preparing low-copper stainless steel according to claim 2, characterized in that: The solution treatment in S6 is to heat up to the solution temperature of 1060-1090°C at a rate of 12-18°C / s, and keep warm for 1.5-2 minutes per millimeter thickness, and then cool by air cooling, mist cooling and water cooling in sequence, with a cooling rate of 100-120°C / s.

9. A method for preparing low-copper stainless steel according to claim 2, characterized in that: The total deformation of cold rolling in S7 is 55-65%, the surface degreasing adopts professional degreasing agent, the conductivity of degreasing liquid is controlled at 5-10ms / cm, and the temperature is controlled at 60-80℃, the solution treatment is to heat up to the solution temperature of 1060-1100℃ at a rate of 12-18℃ / s, and the insulation time is 1.5-2 minutes per millimeter thickness, and then air cooling, mist cooling and water cooling are used in turn, and the cooling rate is 100-120℃ / s, the current of electrolysis is controlled at 3500-4500A, and the temperature is controlled at 65-75℃, the flattening elongation is greater than 0.28%, and the elongation of the tension straightening is greater than 0.3%.

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