Bearing Steels for Induction Hardening – Part II

Abstract

Abstract Surface induction hardening, through induction hardening, and induction tempering of components like rolling elements or rings are established in production and are further developed in research and development. Among others, the used steel grade for induction hardening is one important factor affecting the induction hardening result. The present study benchmarks potential and existing bearing steels in terms of their induction hardening response. Steel grades with low to high carbon contents and different alloying strategies were selected. The robustness of the heat treatment result depending on the selected steels and their conditions prior to induction hardening, shall be pointed out. A dilatometer study was used to compare the sensitivity of martensite start temperature (MS), hardness after quenching, prior austenite grain size, and appearance of non-martensitic transformation products, for varied process parameters. The study showed the pronounced effect of the steels prior microstructure, prior to induction hardening, on the hardening response. The alloying with silicon and manganese reduced the amount of non-martensitic transformation products after hardening. Increasing amounts of alloying elements led in general to larger changes in MS temperature and lower hardness after hardening.