Improving mechanical properties and electrode life for joining aluminum alloys with innovatively designated Newton ring electrode

Abstract

Abstract Aluminum alloys are critical lightweight materials in the automotive industry, which can significantly reduce vehicle weight and improve vehicle fuel efficiency. However, resistance spot welding, as one of key joining approaches, faces the challenges of short electrode life and unstable weld quality when welding aluminum alloy. A novel electrode named as Newton Ring (NTR) electrode was developed to address these issues. The mechanical property, nugget evolution and electrode degradation during continuous welding of aluminum alloy with NTR electrode were investigated and compared with the typical spherical electrode. Results indicate that the mechanical property, electrode life and surface quality of the weld fabricated by NTR electrode were much better than typical one. The improvement in the weld quality with NTR electrode stems from its unique surface morphology, which changes the current density distribution during welding and creates a ring-shaped nucleation process of the nugget. Therefore, the shape and size of the nugget are more stable, and the nugget does not cause serious offset in the continuous welding test. Additionally, the wear of the NTR electrode gradually grows from concentric rings to the base ring, avoiding the random and rapid wear on the electrode weld face, thus improving the surface quality of the weld.