On modelling the influence of thermo-mechanical behavior in chip formationduring 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 100 Cr6 (AISI 52100) bearing steel. A material constitutive law including work hardening, thermal softening, and strain-rate sensitivity has been looked f or. The work hardening effect has been determined with the help of quasi-st atic compression tests performed on standard test specimens. The dynamic co mpression tests performed at "high strain-rates" using the Hopkinson bars, have shown no tendency to viscosity effects. Hot compression tests show tha t 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 i s discussed with a shear instability criterion, presenting the work hardeni ng to thermal softening ratio through a revised material behavior law.