The basic composition of austenitic steel of bearing material is 15% chromium and 8% nickel. Various applications dependon the change of additions quantity.
Firstly, we can classify them by chemical composition. CR series include ferrite series and marten site series. CR-NI series include austenitic series, abnormal series and precipitation hardening series.
Secondly, we can classify them according to metall ographic structure. The classification includes austenitic stainless steel, ferrite stainless steel, marten site stainless steel, duplex stainless steel and precipitation hardening stainless steel.
Finally, we can also classify them according to application. From application angle, there will be nitric acid resistant stainless steel, sulfuric acid resistant stainless steel and saltwater resistant stainless steel. According to corrosion resistance type, theycan be divided into pitting corrosion resistance stainless steel, stress corrosion resistance of stainless steel, inter granular corrosion resistance stainless steel. According to the function characteristic, they can be divided into the non-magnetic stainless steel, free cutting stainless steel, low temperature stainless steel and high strength stainless steel.
However, the most widely used material is 440 C, 440, 420, 304 and 316. According to the change of chemical composition,their corrosion resistance capability increases and the hardness reduce.