Numerical Modeling and Experimental Verification of Residual Stress in Autogenous Laser Welding of High-Strength Steel

Abstract

A three-dimensional finite element (FE) model was developed to numerically calculate the temperature field and residual-stress field in the autogenous laser welding process. The grid independence of the FE model was verified to eliminate the variation of the heat flux between adjacent elements. A cut-off temperature method with combination of the tensile testing was used to consider the effect of high-temperature material properties on the numerical simulation. The effect of the latent heat of fusion and evaporation was also taken into consideration. High compressive initial stress was presented in the selected high-strength steel plates. A subroutine was written to consider the initial stress in the FE mode. Predicted residual stress agreed well with experimental data obtained by an X-ray diffraction technique. Results showed that the transverse and longitudinal residual stresses prevailed in the autogenous laser welding process, and the thermal stress concentration occurred in the molten pool and its adjacent regions. The effect of the welding speed on the distribution of residual stress was also studied. The values of residual stress decreased with an increase in the welding speed.