Modeling the effect of electrode morphology on Mg/steel resistance spot welding

This study focuses on the effect of electrode morphology on Mg/steel resistance spot welding, and explores the optimal electrode combination. A thermo-electro-mechanical coupled numerical model is developed to analyze the contact area, current density, and heat generation, as well as nugget growth during the welding process. Three configurations are investigated (named domed/domed electrodes, domed/conical electrodes, and conical/conical electrodes). The results show that the contact area between sheets when using conical/conical electrodes decreases at first and then increases, while that of other electrode combinations continuously increases. The current density basically shows an opposite variation tendency to that of the contact area. For conical/conical electrodes, expulsion is prone to occur, the indentation is larger, and the wear of the electrodes is the most serious. The difference of Mg nugget diameters under different electrode morphologies is slight, and the nugget thickness is the largest when using the domed/domed electrode combination. The domed/domed configuration performs the best of the three configurations in this study. However, further research should be conducted to investigate the combined effect of electrode configuration and dimensions on the RSW process.