Effect of Electrode Patterning on Melting Behavior and Electrode Degradation in Resistance Spot Welding of A6014-T4 Alloy

Abstract

In this study, the effects of electrode surface design on the resistance spot weldability and degradation of the electrode following resistance spot welding (RSW) of aluminum 6014-T4 alloy were investigated. A new patterning method that can be produced through repetitive pressurization was applied to the electrode, producing a lattice-like pattern shape on the resulting patterned electrode. When RSW was performed using the lattice patterned electrode, the contact resistance decreased because of the effective removal of the oxide film from the surface of the aluminum alloy. As a result, heat generated by resistance on the E/S interface was reduced. Moreover, the growth rate of the weld nuggets formed with the patterned electrode in the thickness direction was lower than that of the nuggets formed with the as-received electrode, and there was comparatively less Cu-Al alloying of the patterned electrode. In addition, a continuous RSW process was performed on the alloy to observe the effect of the electrode surface design on electrode sticking. The results indicated that electrode surface shape can significantly influence resistance heat generation and electrode cooling effects, as well as produce welds with different weld morphology and microstructure. Finally, it was proved that the patterned electrode suffered less electrode degradation through EPMA on the electrode surface after the continuous RSW was completed.