Evaluation of nugget formation in resistance spot welding of dissimilar materials

The scope of this research work focuses on resistance spot welding (RSW) for different material combination where the nugget formation process and microstructure were investigated using both finite element method (FEM) and experimental measurement. The finite element code SYSWELD was utilized for the simulation of a two dimensional axis-symmetric finite element model using customized electrode meshing inorder to develop a thermal-mechanical-electrical characteristic of the spot welds. The model was developed for welding dissimilar metals 1.2 mm low carbon steel and 1.0 mm DP600. The RSW simulation parameters such as welding current, electrode force, welding time and the temperature distribution of the welded sheets and electrodes were considered throughout the study. For the experimental process, similar welding parameters as used in the simulation were applied to the RSW machine. It was found that the weld nugget and HAZ size from numerical simulations were in good agreement with experimental results. Whereas for the microstructure, reasonable results were achieved between the predicted results and experimental observation.