On Predicting Residual Stress and Chip Morphology in Pre-Stressed Hard Turning

To analyze AISI 52100 steel response in hard turning under pre-stressed conditions, an explicit dynamic thermo-mechanical finite element model (FEM) has been developed. The FEM adopts Johnson-Cook constitutive model to describe the workpiece material property; and Johnson-Cook failure model as chip separation criterion; a modified coulomb’s friction law determines the friction behavior at the tool/chip interface. 500MPa of tensile and compressive pre-stress are imposed on the workpiece to simulate the pre-tension-stress and pre-compression-stress conditions respectively in hard turning. The effect of pre-stress on hard turning is determined by analyzing and comparing the simulation results under the three different pr-stress conditions, in terms of saw-tooth chip morphology, cutting forces, plastic strain distribution and temperature distribution on chip, plastic strain distribution and temperature distribution in machined surface, and especially the residual stress in machined surface. It identifies hard cutting under pretension-stress condition is an effective approach to generate a beneficial compressive residual stress profile in hard turning characterized by a bigger value of compressive residual stress and a deeper penetration depth into the hard turned surface which are helpful to enhance the fatigue life of machined components.