Bearing steel is divided into fully hardened bearing steel, carburized bearing steel, stainless bearing steel and high-temperature bearing steel according to chemical composition, performance, processing technology and use. Fully hardened bearing steel is mainly high carbon chromium steel, such as GCr15, with carbon content of about 1% and chromium content of about 1.5%.
In order to improve the hardness, wear resistance and hardenability, some silicon, manganese, molybdenum, etc., such as GCr15SiMn, are properly added. This type of bearing steel has the largest output, accounting for more than 95% of all bearing steel output. Carburized bearing steel is a chromium, nickel and molybdenum alloy structural steel with a carbon content of 0.08~0.23%. The rear surface of bearing parts is carbonitrided to improve their hardness and wear resistance. This steel is used to manufacture large bearings bearing strong impact loads, such as large rolling mill bearings, automobile bearings, mining machine bearings and railway vehicle bearings.
Stainless bearing steels include high carbon chromium stainless bearing steels, such as 9Cr18, 9Cr18MoV, etc., and medium carbon chromium stainless bearing steels, such as 4Cr13, etc., which are used to make stainless and corrosion resistant bearings. High temperature bearing steel is used at high temperature (300~500 ℃). The steel is required to have certain red hardness and wear resistance at the service temperature. High speed tool steel is mostly used instead, such as W18Cr4V, W9Cr4V, W6Mo5Cr4V2, Cr14Mo4 and Cr4Mo4V.
