Numerical Simulation of Laser Welding and Evaluation of Residual Stress and Temperature Distribution in Lap Joint of AA6061 and AA5086 Aluminum Alloys in Different Thicknesses

In the present study, using the ABAQUS 2017 finite element code and using the DFLUX subroutine, a 3D numerical analysis of laser welding in the lap joint of AA6061 and AA5086 aluminum alloys was carried out. The effect of the position of a harder and softer alloy on the upper and lower parts of the weld in two different thicknesses of the two parts was studied on such cases as: thermal distribution, the width of the different welding regions and the residual stress caused by laser welding. In total, and based on the input conditions of the problem, 8 states were prepared for simulation. Based on the results, the A4 sample has the lowest maximum temperature difference between the upper and lower parts in all of these states, which is due to the presence of harder metal with lower thickness in the upper part of the joint. In all cases, regardless of the position of the upper or lower parts, the higher longitudinal residual stresses will occur in the harder part, the AA6061 alloy, and in all states the maximum longitudinal residual stress formed over the yield stress of the harder alloy. Regarding the level of σzz in the workpiece, the best conditions are, respectively, A1 and B1, because they also experience lower residual stresses levels, and the difference in residual stress between the two upper and lower regions of these specimens is lower.