Residual stress control on bearing steel by surface cooled induction heating fast tempering

In order to substituting carburizing while keeping the advantages of case hardening, a new Surface Cooled Induction Heating Fast Tempering (SCIHFT) process has been developed for production of bearings. This process applies to JIS-SUJ2 bearing steel and follows conventional hardening. During SCIHFT tempering, high temperature at the core of the work piece and relatively low temperature at surface cause differences in tempering level, leading to compressive stresses at the surface. As a result, the bearing made by this process has the same rolling contact fatigue life as a carburized bearing. In addition, a simulation method has been developed for residual stress distribution estimation after tempering and clarifying its mechanism. It shows that residual stresses are caused by the difference in volume change during tempering between the core and surface.