On critical condition under adiabatic shear in high speed machining

A linear perturbation analysis is performed to derive an adiabatic shear critical condition in high speed machining and the effects of strain hardening and thermal softening on adiabatic shear are investigated for thermal softening induced plastic instability in rate dependent materials. The criterion indicates that the materials became unstable once the thermal softening overcomes the strain hardening, regardless of the strain rate. The adiabatic shear is likely to form under the conditions of smaller strain hardening index, larger thermal softening index.