1910 to 1914 was born in the organization of martensitic, ferritic and austenitic stainless steel, respectively, from the chemical composition, mainly belong to Fe-Cr and Fe-Cr-Ni two major systems. From the end of World War I to the end of World War II in nearly three decades (i.e., 1919 to 1945). With the development of various industries, stainless steel to adapt to the working conditions and the differentiation, that is, in the original two systems based on the three organizational state, by increasing or decreasing the carbon content and adding a variety of other alloying elements and the derivation of many new types of stainless steel. From the end of the second big station until now more than thirty years, mainly to adapt to the seawater or salt corrosion candle, absorb Y rays and neutrons, to obtain ultra-high strength, saving nickel and other needs and the development of pitting-resistant stainless steel, stainless steel for the atomic energy industry, precipitation hardening stainless steel and manganese nickel stainless steel.

      In recent years. In order to solve the austenitic stainless steel intergranular corrosion candle and stress corrosion problems, and the development of ultra-low carbon stainless steel and ultra-pure ferritic stainless steel, respectively. At present, the variety of stainless steel has been put into the market has reached more than 230 species, often used nearly 50 species, of which about 80% are austenitic stainless steel (18 chromium - 8 nickel) derivatives, while the remaining 20% are evolved from 13 chromium steel. The most significant research and development on stainless steel grades is focused on two aspects:

◆ The first aspect is to improve the corrosion resistance of steel, which is the study of 18-8 steel intergranular corrosion candle problem, not only the development of the steel grade, proposed a process to solve this interproblem. It also promotes research on the passivation and corrosion mechanism of stainless steel.

◆ The second aspect is the development of high-strength stainless steel (i.e. precipitation-hardening stainless steel), this steel is developed after World War II with the progress of aviation, space and rocket technology. Among them, semi-austenitic precipitation hardening stainless steel has excellent process properties (17-7PH class), solid solution treatment is very easy to process and form, and the subsequent strengthening heat treatment (aging treatment) temperature is not high deformation is very small, in the United States this steel is used for aviation structures, and has been mass production, countries also have similar steel into use.