Temperature and residual stress field analysis in double-pulse MIG welding of AA6061-T6 aluminum alloy thin sheets

Accurately predicting the weld temperature field and post-weld residual stress field is of utmost significance for comprehending the composition of welded structures and enhancing their service performance. In this study, the double-pulse MIG welding process of AA6061-T6 aluminum alloy thin sheets was investigated. A dynamic combined heat source model, consisting of double ellipse and double ellipsoid heat sources, was proposed based on weld bead morphology and the current variation during the welding process. The temperature and residual stress fields were numerically simulated and experimentally measured using thermocouple temperature measurements and blind hole methods, respectively. Simulation results of the combined heat source model were found to be accurate and in good agreement with the experimental data. The effects of welding fixtures and convective heat transfer coefficients on the results were also considered. The welding temperature and post-weld residual stress properties of the welded structure were thoroughly examined. During the welding process, the highest temperature is about 1500 °C and the maximum longitudinal residual stress occurs in the heat-affected zone, which is approximately 250 MPa, slightly lower than the yield strength of the base material.