Grain size sensitive–MTS model for Ti-6Al-4V machining force and residual stress prediction

Abstract

Material properties are significantly influenced by the parameters of the machining process. The accurate prediction of machining force and residual stress reduces power consumption, enhances material properties, and improves dimensional accuracy of the finished product. Traditional method using the finite element analysis (FEA) costs a significant amount of time, and the archived mechanical threshold stress (MTS) model without consideration of microstructure of the material yields inaccurate result. In this paper, a grain size–sensitive MTS model is introduced for the machining process of Ti-6Al-4V. A grain size–sensitive term is introduced to the modified MTS model to account for evolution of the grain size. The grain size–sensitive MTS model takes the microstructure of the Ti-6Al-4V into consideration for the calculation of machining force and residual stress. The grain size–sensitive term is introduced into the athermal stress component using the initial yield stress, strain hardening coefficient, and the Hall-Petch coefficient. The analytical result is compared with those of experimental studies and the traditional Johnson-Cook model to prove the validity in the prediction of machining force and residual stress. The proposed model explores a new area for calculating cutting forces and residual stress.