Development of stainless steel

The microstructure of martensite, ferrite and austenitic stainless steel was born in 1910 ￣ 1914, and was mainly composed of Fe - CR and Fe - Cr - Ni system from the chemical composition. From the end of the first world war to the nearly three decades after the end of the second world war ( 1919 - 1945 ). With the development of various industries, stainless steel has been differentiated to adapt to working conditions, that is, on the basis of the three organizational States of the original two systems, many new types of stainless steel have been derived by increasing or decreasing carbon content and adding many other alloying elements. From the end of the second station to the present, for more than 30 years, mainly adapt to the anti - sea water or salt decay candle, absorb y - ray and neutron, gain ultra-high strength, save nickel and other needs, developed the anti - pitting stainless steel, atomic industrial stainless steel, precipitation hardening stainless steel and manganese - nitrogen - substituted nickel stainless steel. In recent years, in order to solve the problem of intergranular corrosion and stress corrosion of austenitic stainless steel, the ultra-low carbon stainless steel and ultra pure ferritic stainless steel have been developed. At present, the number of stainless steel in the market has reached more than 230, and there are nearly 50 kinds of them, about 80 % of them are derivatives of austenitic stainless steel ( 18 CR - 8 nickel ), while the other 20 % is made of 13 CR steel. The most important research and development on stainless steel is focused on two aspects:

 

The first aspect is to improve the corrosion resistance of steel, of which 18 - 8 steel intergranular corrosion of the candle problem, not only the development of steel, put forward the solution to this problem. The mechanism of passivation and corrosion of the stainless steel was also studied. 

 

The second aspect is the development of high strength stainless steel ( i.e, precipitation hardened stainless steel ), which developed after the second world war with the progress of aviation, space and rocket technology. Semi - austenitic precipitation hardened stainless steel has excellent technological properties ( 17 - 7PH ), it is easy to be processed after solution treatment, and the subsequent strengthening heat treatment ( aging treatment ) is not high temperature deformation is very small, in the United States, the steel is mostly used for aviation structure, and has been produced in large quantities, and similar steel has been put into use in all countries.