Finite element simulation of residual stress in machining of Ti-6Al-4V with a microstructural consideration

Abstract

Machining-induced residual stress plays significant role in the corrosion resistance and fatigue life of the manufacturing end-product. The high temperature condition in the turning process could induce microstructure changes of titanium alloys, which would directly influence the residual stress generation in the machining process. A prediction model is proposed to calculate the microstructure evolution in orthogonal turning process. Based on the explicit calculation of grain size growth and phase transformation, a microstructure-sensitive Johnson–Cook model considering the material microstructural attributes is developed for the machining-induced residual stress prediction of Ti-6Al-4V. Grain size characterization with electron backscatter diffraction test is conducted on the machined workpiece surface. Experimental measurement on force and residual stresses are conducted for model validations. The predicted force value agrees well with the measurement data. The general trend of residual stress profile is captured by the prediction model. The mechanisms of how the residual stress would be influenced by the different machining conditions, such as surface cutting speed, and feed rate, are also studied. The proposed method provides an in-depth understanding on the machined workpiece residual stress distribution as influenced by material microstructural attributes evolution in the machining process.