Enhancing the strength of Al-Cu-Mg alloy resistance spot welds under high vacancy concentration via post-weld down-slope current

This study addresses the strength loss issue of an Al-Cu-Mg alloy resistance spot welds by in situ enhancing the mechanical properties through a novel post-weld down-slope current technique. By applying a down-slope current to actively utilize the high vacancy concentration generated during welding, the joints achieved a 22.9 % higher load-bearing capacity after 6 months of natural aging than conventional methods. The high cooling rates during welding create elevated concentrations of excess vacancies, which in turn promote solute atom clustering and accelerate the subsequent natural aging process. This method proves to enhance the mechanical properties of the joints more effectively than conventional welding techniques.