Residual stress and microstructure of Ti6Al4V treated by thermal-vibratory stress relief process

Abstract

The stress relief processes, such as thermal stress relief (TSR) and vibratory stress relief (VSR), are generally applied to decrease and control the residual stress in the manufacturing process. Thermal-vibratory stress relief (TVSR) is a novel stress relief method developed in recent years, which has significant advantages over traditional methods. The stress relief mechanism of TVSR and stress evolution under the coupling effect of heat and vibration still need further investigation. In this study, TSR, VSR and TVSR with different process parameters are compared to study their stress relief effect on Ti6Al4V, and corresponding FEM simulations are performed to calculate the stress evolution. The residual stress is measured using X-ray diffraction method. EBSD and TEM characterizations are carried out to investigate the influences on the phase, crystal grain and dislocation. Results show that both TVSR and TSR can eliminate over 90% of residual stress of Ti6Al4V, but the efficiency of TVSR is 4.2 times as that of TSR. The stress relief rate of TVSR is 45.04% higher than that of VSR with the same dynamic stress. Finally, the quantitative relationship between TVSR parameters and residual stress is established, and the stress relief mechanism and effective parameter region of TVSR are analyzed.