Influence of Carbide Spheroidisation Process on Wear Resistance of Hardened 100CrMnSi6-4 Steel
Co-authors: Jaromir Dlouhy, Jana Niznanska
Heat treating of bearing steels is a complex procedure, typically involving soft annealing and hardening. The purpose of soft annealing is to provide machinability and formability. Soft annealing, which essentially leads to carbide spheroidisation, may take up to tens of hours, owing to its diffusion processes. The process which was newly developed by the company COMTES FHT shortens the duration of carbide spheroidisation by orders of magnitude and provides the beneficial starting microstructure for subsequent hardening. Hardening consists of quenching and tempering. Its goal is to provide adequate hardness and wear resistance of the final parts. The resulting microstructure properties of hardened steel depend not only on the quenching and tempering parameters but on the spheroidised microstructure configuration as well. The present paper explores the properties and microstructure of hardened 100CrMnSi6-4 bearing steel with regard to its microstructural fineness after spheroidisation and the quenching temperature. Finer globular carbides lead to smaller austenite grain in the quenching process and to finer martensite. The microstructure evolution was mapped at individual stages of the process and the material’s hardness and wear resistance was evaluated by means of a tribometer.