On adiabatic shear fracture in high-speed machining of martensitic precipitation-hardening stainless steel

The serrated chip produced in high-speed machining of martensitic precipitation-hardening stainless steel is inevitably tore up into isolated segments due to adiabatic shear fracture with the further increase of cutting speed. The induced mechanism of adiabatic shear fracture and the corresponding damage process in high-speed machining are investigated through quick-stop tests and chip morphology examinations. The isolated segments generated due to adiabatic shear fracture which is found in the rate-related process of adiabatic shear evolution is a cyclic process of energy convergence and release with ductile-brittle damage transition. The fracture energy of adiabatic shear band approaches a stable saturation limit with the increases of cutting speed and feed. On the basis of saturation limit model, the critical fracture energy is predicted by cutting conditions and compared with the experimental results.