Prediction model and experimental investigation of residual stress in milling of Ti-6Al-4V titanium alloy considering phase transformation

Ti-6Al-4V titanium alloy, known for its machining challenges, develops residual stresses on its surface during cutting, which significantly influence the performance of the machined parts. During the milling process, the role of phase transformation in affecting residual stress is crucial. This paper introduces a predictive model for milling-induced residual stress that integrates milling forces, thermal effects, and material phase transformation. Initially, the study examines how machining parameters, including cutting speed and feed per tooth, influence phase transformation in the surface layer of Ti-6Al-4V during milling. Subsequently, a phase transformation theoretical model is incorporated, employing finite element (FE) numerical simulations alongside the analysis of scanning electron microscope (SEM) images to determine the volume fractions of dual phases. By integrating this with a flow stress model, a comprehensive predictive model for milling residual stress is developed. Finally, experimental results are compared with the FE model predictions, showing maximum errors of 8.65% and 10.50% in the X and Y directions of residual stress, respectively, validating the model’s accuracy and effectiveness.