Simulation Study on Residual Stress Distribution of Machined Surface Layer in Two-Step Cutting of Titanium Alloy

Abstract

Ti-6Al-4V titanium alloy is known as one of the most difficult metallic materials to machine, and the machined surface residual stress distribution significantly affects properties such as static strength, fatigue strength, corrosion resistance, etc. This study utilized finite element software Abaqus 2020 to simulate the two-step cutting process of titanium alloy, incorporating stages of cooling, unloading, and de-constraining of the workpiece. The chip morphology and cutting force obtained from orthogonal cutting tests were used to validate the finite element model. Results from the orthogonal cutting simulations revealed that with increasing cutting speed and the tool rake angle, the residual stress undergoes a transition from compressive to tensile stress. To achieve greater residual compressive stress during machining, it is advisable to opt for a negative rake angle coupled with a lower cutting speed. Additionally, in two-step machining of titanium alloy, the initial cutting step exerts a profound influence on the subsequent cutting step, thereby shortening the evolution time of the Mises stress, equivalent plastic strain, and stiffness damage equivalent in the subsequent cutting step. These results contribute to optimizing titanium alloy machining processes by providing insights into controlling residual stress, ultimately enhancing product quality and performance of structural part of titanium alloy.