An investigation of mechanical-thermal coupling treatment on material properties, surface roughness, and cutting force of Inconel 718

It is common that Inconel 718 is difficult to cut, which limits its application unavoidably. In this study, the mechanical-thermal coupling (MTC) treatment method is applied to improve the machinability of Inconel 718. After MTC treatment on Inconel 718 surface, the severe plastic deformation is produced easily, and the grain is refined without new substance produced. Moreover, a theoretical and computational model taking account of the electric field, thermal field, and mechanical field simultaneously is proposed so as to predict the temperature and stress distributions during MTC treatment. Furthermore, the influence of peak current during MTC treatment on the material properties and the machinability of Inconel 718 in ultra-precision machining have been investigated. Results show that the workpiece surface grain size decreases and the thickness of the deformation layer increases with the increasing peak current. Moreover, with the appropriate MTC parameters, the small cutting force and the high cutting surface quality are obtained compared without MTC treatment, so MTC treatment can be used as an effective method for improving the machinability of Inconel 718 without deteriorating its base material performance, which is in favor of the application of the treated workpiece after machining.