Finite Element Method (FEM) Simulation of the Residual Stress in Ti6Al4V Following Warm Laser Peening
X.K. Meng, J.Z. Zhou, C. Su, J. Sheng, X.W. Yang and H.S. Chen
Warm laser peening (WLP) is a thermo-mechanical treatment technique combining the advantages of high strain rate and high temperature, it is proved to have significant effects on the residual stress and microstructure induced by treating metals and alloys at elevated temperatures; however, the relationship between compressive residual stress (CRS) and WLP temperatures is not convincing yet. In this study the effects of laser peening at room temperature and WLP at elevated temperatures of 100 to 400°C on the CRS of Ti6Al4V alloy were investigated by finite element method (FEM). The hardening and thermal softening effects on plastic flow were analysed, the CRS before and after rebound process was obtained and thus the distribution of CRS in WLP specimens was investigated. The results showed that WLP temperatures have important influence on the amplitude and distribution of CRS. Affected by the hardening effects, the amplitude of CRS increases gradually as temperature increases from 20 to 100°C; however, when the temperature exceeds 100°C, there is a significant decrease in the amplitude of CRS due to the increasing thermal softening effects. Moreover, the uniformity, affected width and affected depth of CRS are significantly improved by the 400°C WLP.
Keywords: Warm laser peening (WLP), Ti6Al4V, compressive residual stress (CRS), finite element method (FEM), plastic flow, hardening, thermal softening