Modelling the effects of twinning and dislocation induced strengthening in orthogonal micro and macro cutting of commercially pure titanium

This paper presents a physics based Finite Element (FE) model to explore the microstructural phenomena occurring during severe plastic deformation processes, taking into account the influence of deformation-induced twinning, dislocation accumulation, and grain size evolution. In particular, the model was exploited to analyse the strengthening behaviour of Commercially Pure Titanium (CP-Ti) subjected to orthogonal cutting processes. Orthogonal cutting experiments were performed to validate the FE model in terms of cutting forces, chip morphology, microstructure, and workpiece surface hardness. The model is also used to analyse the individual contributions of dislocation accumulation, crystal twinning, and grain size refinement phenomena to material strengthening. The results show that dislocation accumulation and twinning are the main contributors to workpiece surface hardening in cutting of CP-Ti under the conditions studied in this work. Moreover, the model was employed to investigate additional cutting conditions, demonstrating a useful capability to improve the manufacturing process to obtain superior performance.