A physically based constitutive model for predicting the surface integrity in machining of Waspaloy

During machining, surface modifications are directly related to the process dynamic affecting the thermo-mechanical properties of the materials. The physics phenomena (such as dynamic recrystallization, hardening and recovery effects) are difficult to be experimentally evaluated during the cutting operations, therefore the simulations are very important tools to understand their evolution. Orthogonal cutting experiments were conducted on Waspaloy under different cutting parameters and lubri-cooling conditions. The machined surfaces were evaluated via optical microscope and the surface integrity was analysed in terms of microstructural changes and microhardness. The deformation mechanisms that occurred in chip formation and on the machined surface were investigated in order to build-up a physically based constitutive model. Subsequently, the developed material model was implemented via sub-routine in a commercial Finite Element software. The numerical prediction strategy was validated through comparisons with experimental outcomes (cutting forces, temperature and metallurgical changes) and employed to predict the variables of scientific interest (microstructural modifications and microhardness). The overall absolute error in predicting the principal cutting force, feed force and temperature were approximately equal to 5%, 9% and 7% respectively. Furthermore, the developed model permits to explore the metallurgical changes and their evolution during the machining process varying cutting parameters and lubri-cooling conditions.