On modelling the influence of thermo-mechanical behavior in chip formation during hard turning of 100Cr6 bearing steel

This paper deals with turning of hardened alloy steels (up to HV800). First, the research focuses on the evaluation of flow stress in machining of 100Cr6 (AISI 52100) bearing steel. A material constitutive law including work hardening, thermal softening, and strain-rate sensitivity has been looked for. The work hardening effect has been determined with the help of quasi-static compression tests performed on standard test specimens. The dynamic compression tests performed at high strain-rates using the Hopkinson bars, have shown no tendency to viscosity effects. Hot compression tests show that thermal softening plays a significant role in the the process feasibility. Cutting tests performed under various cutting conditions have highlighted the conflicting work hardening-thermal softening processes. This balance is discussed with a shear instability criterion, presenting the work hardening to thermal softening ratio through a revised material behavior law.