Aluminum alloys are widely used in lightweight structures owing to their good corrosion resistance and low density. However, achieving durable joints remains challenging when using conventional welding methods because of the formation of stable surface oxide films and the high thermal conductivity of aluminum alloys. As an alternative joining technique, self-piercing riveting is commonly employed in industrial applications; nevertheless, it often suffers from stress concentration, fretting wear, and a consequent reduction in fatigue strength. In this study, spot impact welding was explored as a potential solid-state joining method for aluminum alloys. Impact experiments were conducted on A5052 aluminum alloy under various impact velocities and impactor geometries to clarify the mechanisms of oxide film disruption and joint formation. The post-impact joint characteristics were evaluated through cross-sectional observations using optical microscopy, combined with laser-induced breakdown spectroscopy to investigate the elemental distributions near the bonding interface. The results demonstrated that changes in the impact velocity and impactor shape significantly influenced the interfacial contact behavior, oxide film distribution, and continuity of the aluminum matrix. Under appropriate impact conditions, effective oxide removal and direct metal-to-metal contact were achieved, leading to the formation of metallurgical bonding. The bonding behavior was further interpreted from a continuum-mechanics perspective, highlighting the role of shear-driven interfacial material flow in oxide removal and localized metallurgical bonding. These findings provide new insights into the interfacial mechanisms governing spot impact welding and highlight its potential applicability as a reliable joining technique for lightweight aluminum structures.
ZHU et al. (Thu,) studied this question.