Prediction of surface residual stress of micro-milling Inconel 718 thin-walled parts considering the initial stress state

Abstract

Thin-walled micro parts generate surface residual stress after micro-milling. Due to their weak rigidity, thin-walled parts are deformed under residual stress, making it difficult to ensure machining accuracy. The life, wear resistance, and precision durability of the parts are affected by the residual stresses. Therefore, predicting the surface residual stresses on micro-milling thin-walled parts is important. Most of the simulation models for predicting surface residual stresses assume that the initial residual stress is 0, resulting in poor prediction accuracy. In view of the above problems, this paper proposes a method for predicting the surface residual stresses of thin-walled parts in micro-milling by considering the initial stress state, which is novel in that the rough machining process of blank with initial residual stress of 0 is simulated by finite element method, and the stress state of machined parts is taken as the initial condition for thin-wall micro-milling to continue simulation, so as to realize the surface residual stress prediction of thin-wall micro-milling considering the initial stress state. Based on ABAQUS, the geometric models of tools and workpieces are established, and meshing are carried out. The Johnson-Cook model is used to describe the material relationship, and the friction model is determined to establish the rough milling simulation model. The simulation result is used as the initial conditions to establish the micro-milling simulation model, which realized the simulation of the micro-milling residual stresses on the thin-walled parts of Inconel 718. The micro-milling experiments are carried out, which verified the effectiveness of the model. The results show that the thin-walled micro-milling simulation model considering the initial residual stress can accurately predict the residual stress of the machined surface. Then the causes of simulation errors are analyzed, and the research provide a reference for the prediction of residual stress in micro-milling of thin-walled parts.