The tissues born in 1910-1914 were martensitic, ferrite and austenitic stainless steels. From the chemical composition, they are mainly Fe-Cr and Fe-Cr-Ni. In the nearly three decades from the end of the First World War to the end of the Second World War, the development of stainless steel round steel, 304 stainless steel round steel stainless steel (ie 1919 to 1945). With the development of various industries, stainless steel has been differentiated to adapt to working conditions, that is, based on the three organizational states of the original two systems, many of them have been derived by increasing or decreasing the carbon content and adding various other alloying elements. New stainless steel. In the more than 30 years from the end of the second station to the present, it has developed anti-pitting stainless steel mainly for adapting to seawater or salt-corrosion candle, absorbing Y-rays and neutrons, obtaining ultra-high strength, saving nickel, etc. , Atomic energy industrial stainless steel, precipitation hardened stainless steel and manganese nitrogen nickel stainless steel. In recent years. In order to solve the problem of intergranular decay candle and stress corrosion of austenitic stainless steel, ultra-low carbon stainless steel and ultra-pure ferritic stainless steel were developed respectively. At present, there are more than 230 varieties of stainless steel that have been put on the market, and nearly 50 kinds are frequently used, of which about 80% are derivatives of austenitic stainless steel (18 chrome-8 nickel), and the remaining 20% are Developed from 13 chrome steel. The most important research and development on stainless steel grades is concentrated in two areas
◆ The first aspect is to improve the corrosion resistance of steel. The research on the problem of intercalation of 18-8 steel intergranular candle not only develops steel grade, but also proposes a process to solve this problem. Research on the passivation and corrosion mechanisms of stainless steel has also been promoted.
