Predictive modelling of microstructure changes, micro-hardness and residual stress in machining of 304 austenitic stainless steel

The machined surface integrity plays a critical role in the corrosion resistance and fatigue property of austenitic stainless steels. This work develops an analytical model for prediction of microstructural changes, micro-hardness and residual stress in machining of 304 austenitic stainless steel. The distributions of stress, strain and temperature are first modelled by building up a multi-physics framework of orthogonal cutting process. Then, the martensitic transformation is modelled based on strain-induced martensitic transformation kinetics. The micro-hardness variation is subsequently predicted by a model which accounts for both dislocation density and phase transformation evolution processes. Finally, the residual stress is derived from a relaxation procedure. Experimental tests are conducted for the model validation. The predicted results in terms of cutting force, martensite fraction, micro-hardness, and residual stress are in good agreement with the measured data.