Overall Residual Stresses in the Resistance Spot Welding Joint of Dissimilar Aluminum Alloys

A thermal-electric-mechanical coupling finite element model is established based on the instrumented indentation test and the finite element theory. The resistance spot welding(RSW) process of 5083 and 7 N01 aluminum alloy is simulated. The distribution of the residual stress in the joint is obtained. The experiment of resistance spot welding is carried out. The morphology of the nugget, the distribution of hardness and residual stresses on upper and lower surfaces are obtained by using the metallographic microscope, the hardness tester and the sectioning relaxation stain-gage method, respectively. The influences of mechanical properties on values and distributions of the residual stress are discussed. The experimental results show that the nugget and the heat affected zone(HAZ) are softened after RSW. Compared with the 7 N01 base metal, the hardness and flow stress of the nugget and the HAZ significantly decreased. The simulation results show that the influence of mechanical properties on the distribution of residual stresses is small. The mechanical properties mainly influence the values of the residual stresses. The residual stress in the nugget is a three dimensional stress of tension. The peak value of the residual stress appears at the center of the nugget. The predicted residual stresses from the developed finite element model agree well with experimental results.