On microstructure and properties of Si modified 100Cr6 bearing steels

As an alloying element to increase the resistance to softening during tempering, silicon content was modified to investigate its effect on the microstructure and properties of 100Cr6 bearing steel. It turned out that increasing the silicon content brought about two difficulties in the manufacturing process, promoting the decarburisation during heating and/or hot rolling and retarding the spheroidisation of cementite. The maximum size of non-metallic inclusions was predicted to reduce evidently with increasing silicon content, although the total oxygen content in steels was nearly the same. There has been no fine carbide precipitation during tempering that can be attributed to the increasing silicon content, leading to the stabilisation of retained austenite due to the diffusion of carbon atoms from martensite. As a result, the new Si modified high carbon chromium bearing steel showed superior rolling contact fatigue characteristics to conventional steel.