What are the types of stainless steel development

Stainless steel usually refers to steel that can resist corrosion in the atmosphere or some chemical media. According to the characteristics of the structure, it can be divided into five categories: martensite, austenite, ferrite, austenite-ferrite, and precipitation hardening. Among them, martensitic and ferritic stainless steels are chromium-based steels, and other types of stainless steels are chromium-nickel-based steels. According to different purposes, stainless steel can be processed into various varieties such as plates, tubes, shapes, wires and their products. From the perspective of the consumption structure of stainless steel, stainless steel plates and strips (including medium and thick steel plates, hot-rolled thin plates, and cold-rolled thin steel strips) account for about 75% to 80% of the total consumption of stainless steel, and other stainless steel varieties only account for 25% about. At present, the world’s major stainless steel manufacturers include Thyssen-Krupp (KTS), Arcelor, and Avesta, with an annual output of more than 2 million tons; the major stainless steel manufacturers in China are Taigang and Baosteel, there are some private enterprises. Stainless steel is widely used in construction, chemical industry, light industry, home appliances, energy, aerospace, food processing, kitchen equipment, medical equipment and catering industry because of its good oxidation resistance, corrosion resistance and decoration. It plays an increasingly important role in various industries of the national economy and people’s living consumption. In recent years, the rapid development of petrochemical industry, military industry and marine development has put forward higher requirements for stainless steel. Traditional stainless steel can no longer meet the requirements of special industries and special functional fields. Therefore, stainless steel materials are also developing in the direction of functionality and particularity. Super stainless steel and functional stainless steel that meet various special functional requirements have emerged.

Super stainless steel According to the microstructure characteristics of stainless steel materials, super stainless steel is divided into several types such as super ferritic stainless steel, super austenitic stainless steel, super martensitic stainless steel and super duplex stainless steel. Super austenitic stainless steel Super austenitic stainless steel is based on ordinary austenitic stainless steel, by improving the purity of the alloy, increasing the number of beneficial elements (Cr, Mo), reducing the carbon content, and preventing the precipitation of Cr23C6 from causing intergranular corrosion. Obtain good mechanical properties, process properties and local corrosion resistance, and replace Ti stabilized stainless steel. Super ferritic stainless steel Super ferritic stainless steel inherits the characteristics of ordinary ferritic stainless steel, such as high strength, good oxidation resistance, and excellent stress corrosion resistance. At the same time, it improves the ductility-brittle transition of ferritic stainless steel and is more resistant to intergranular corrosion. Limitations such as sensitivity and low toughness in the as-welded state. Refining technology is used to reduce carbon and nitrogen content, adding stabilizing and weld metal toughening elements, to obtain super ferritic stainless steel with high chromium, molybdenum and ultra-low carbon and nitrogen, making ferritic stainless steel resistant to corrosion and The application of chloride pitting and crevice corrosion has entered a new stage. Super duplex stainless steel Super duplex stainless steel was developed in the late 1980s, and the main grades are SAF2507, UR52N, Zeron100 and so on. This type of steel is characterized by low carbon content (0.01%～0.02%), high molybdenum and high nitrogen (Mo≤4%, N≤0. 3%), the ferrite phase content in steel accounts for 40% to 45%, which has excellent pitting corrosion resistance. Super martensitic stainless steel Martensitic stainless steel is a hardenable stainless steel with high hardness, strength and wear resistance, but its toughness and weldability are poor. Ordinary martensitic stainless steel lacks sufficient ductility and is very sensitive to stress during the deformation process, and cold forming is difficult. By reducing the carbon content and increasing the nickel content, super martensitic stainless steel can be obtained. In recent years, various countries have invested heavily in the development of low-carbon and low-nitrogen super martensitic steels, and developed a batch of super martensitic steels for different purposes. Now, super martensitic steel has been widely used in oil and natural gas extraction, storage and transportation equipment, hydroelectric power generation, chemical industry and high-temperature pulp production equipment. Functional stainless steel Since 1960, countries all over the world have put forward higher requirements on the quantity, variety and quality of stainless steel. With the changes in market demand, various stainless steels with special purposes and special functions continue to appear. Nitrogen-containing stainless steel Nitrogen-containing stainless steel is one of the stainless steel varieties that have developed rapidly in recent years and has attracted increasing attention. Nitrogen is added as an alloying element to stainless steel, which can improve the stability of austenite, balance the phase ratio of dual-phase steel, increase the strength of steel without affecting the plasticity and toughness of steel, and can partially replace Ni in stainless steel. In dual-phase steel, nitrogen delays the dispersion and precipitation of intermetallic compounds; in martensitic steel, nitrogen and other elements form nitrides distributed on the grain boundary, which can improve the hardening ability and prevent austenite and ferrite during high temperature tempering The growth of bulk crystal grains. Dual-phase steels with high nitrogen content have good resistance to uniform corrosion and localized corrosion. New type of medical nickel-free austenitic stainless steel At present, medical implant stainless steel materials are mainly chromium-nickel austenitic stainless steel (such as 316L, etc.), which has good biocompatibility and contains 13% to 15% nickel. Nickel is the main alloying element in austenitic stainless steel and has a strong effect on the formation and stabilization of the austenitic phase zone. However, nickel is a kind of sensitizer, and it is teratogenic and carcinogenic to organisms. If nickel-containing implanted stainless steel is used in the body for a long time, it will gradually be destroyed and release nickel ions. When nickel ions are enriched in the tissues near the implanted human body, it can induce toxic effects and cause adverse reactions such as cell destruction and inflammation. The chromium-manganese-nitrogen-type medical nickel-free austenitic stainless steel developed by the Institute of Metal Research of the Chinese Academy of Sciences has been tested for biocompatibility and has better performance than the chromium-nickel austenitic stainless steel (316L) currently in clinical use. Antibacterial stainless steel With the improvement of people’s living standards, people pay more and more attention to the environment and their own health, which promotes the research and development of antibacterial materials. Since 1980, developed countries represented by Japan have begun to research and apply antibacterial materials in household appliances, food packaging, daily necessities, and bathing equipment. Nisshin Steel Co., Ltd. and Kawasaki Iron and Steel Co., Ltd. respectively developed antibacterial stainless steels containing Cu and Ag. Cu-containing antibacterial stainless steel is made by adding 0.5% to 1.0% of Cu to the stainless steel and adopting special heat treatment to uniformly disperse ε-Cu precipitates from the surface to the inside of the stainless steel, which has an antibacterial effect. This Cu-containing antibacterial stainless steel is suitable for use in high-end kitchen appliances and other products and other products that require high processability and antibacterial properties. Antibacterial stainless steel with Ag has a high antibacterial effect against Escherichia coli and Staphylococcus aureus. This material can always maintain a good antibacterial effect especially when it is processed and ground or the surface is abraded. With the growth of China’s national economy and the improvement of people’s living standards, the apparent consumption of stainless steel increased from 260,000 tons in 1990 to 1.73 million tons in 2000, with an average annual growth rate of 17.73%, exceeding the world average of 5%. level. In 2002, China’s total consumption of stainless steel reached 3.2 million tons, surpassing the United States (over 2 million tons of stainless steel per year), and it has taken the first place in the world. However, according to current production estimates, China’s per capita stainless steel consumption has not reached 1.5 kg/year, which is lower than the world’s per capita stainless steel consumption of about 2 kg/year. In the past 10 years, the per capita consumption of stainless steel in western industrialized countries has increased significantly. The country with the highest stainless steel consumption is Austria, reaching 25 kg/year; the United States is second; followed by Japan, Germany, Italy, France, South Korea and the United Kingdom, reaching 25 kg/year. 10 kg ~ 15 kg/year. It can be seen that the development prospects of China’s stainless steel market are very broad. 0% Cu, and special heat treatment is adopted to uniformly disperse ε-Cu precipitates from the surface to the inside of the stainless steel, which has an antibacterial effect. This Cu-containing antibacterial stainless steel is suitable for use in high-end kitchen appliances and other products and other products that require high processability and antibacterial properties. Antibacterial stainless steel with Ag has a high antibacterial effect against Escherichia coli and Staphylococcus aureus. This material can always maintain a good antibacterial effect especially when it is processed and ground or the surface is abraded. With the growth of China’s national economy and the improvement of people’s living standards, the apparent consumption of stainless steel increased from 260,000 tons in 1990 to 1.73 million tons in 2000, with an average annual growth rate of 17.73%, exceeding the world average of 5%. level. In 2002, China’s total consumption of stainless steel reached 3.2 million tons, surpassing the United States (over 2 million tons of stainless steel per year), and it has taken the first place in the world. However, according to current production estimates, China’s per capita stainless steel consumption has not reached 1.5 kg/year, which is lower than the world’s per capita stainless steel consumption of about 2 kg/year. In the past 10 years, the per capita consumption of stainless steel in western industrialized countries has increased significantly. The country with the highest stainless steel consumption is Austria, reaching 25 kg/year; the United States is second; followed by Japan, Germany, Italy, France, South Korea and the United Kingdom, reaching 25 kg/year. 10 kg ~ 15 kg/year. It can be seen that the development prospects of China’s stainless steel market are very broad. 0% Cu, and special heat treatment is adopted to uniformly disperse ε-Cu precipitates from the surface to the inside of the stainless steel, which has an antibacterial effect. This Cu-containing antibacterial stainless steel is suitable for use in high-end kitchen appliances and other products and other products that require high processability and antibacterial properties. Antibacterial stainless steel with Ag has a high antibacterial effect against Escherichia coli and Staphylococcus aureus. This material can always maintain a good antibacterial effect especially when it is processed and ground or the surface is abraded. With the growth of China’s national economy and the improvement of people’s living standards, the apparent consumption of stainless steel increased from 260,000 tons in 1990 to 1.73 million tons in 2000, with an average annual growth rate of 17.73%, exceeding the world average of 5%. level. In 2002, China’s total consumption of stainless steel reached 3.2 million tons, surpassing the United States (over 2 million tons of stainless steel per year), and it has taken the first place in the world. However, according to current production estimates, China’s per capita stainless steel consumption has not reached 1.5 kg/year, which is lower than the world’s per capita stainless steel consumption of about 2 kg/year. In the past 10 years, the per capita consumption of stainless steel in western industrialized countries has increased significantly. The country with the highest stainless steel consumption is Austria, reaching 25 kg/year; the United States is second; followed by Japan, Germany, Italy, France, South Korea and the United Kingdom, reaching 25 kg/year. 10 kg ~ 15 kg/year. It can be seen that the development prospects of China’s stainless steel market are very broad.