Employing the electrode of different diameters to join dissimilar Al-Cu thin sheets using resistance spot welding

Abstract

This study aims to clarify the intricate connection between using different electrode tip diameters and the quality of spot joints. By investigating basic principles and process parameters, the research highlights how various combinations of electrode sizes affect weld quality. Specifically, to join aluminum (Al) and copper (Cu), two electrode sizes were employed: 4 mm and 8 mm tip diameter. Given that copper has higher conductivity (398 W/mK) and a higher melting temperature (1085 °C) compared to aluminum (237 W/mK and 660 °C respectively), efforts were made to enhance current density towards the copper side by using the smaller electrode tip diameter (4 mm) on that side. Experiments were conducted using two different combinations of sheet thicknesses (0.5 mm and 1 mm), revealing the need for optimized electrode tip diameter combinations for varying sheet thicknesses and materials with different thermos-physical properties. Overall, this study seeks to deepen our understanding of resistance spot welding, specifically focusing on the importance, challenges, and future prospects associated with varying electrode tip diameters in joining dissimilar metals.