Influence of laser beam shaping strategies on the microstructure and mechanical performance of aluminium to Hilumin dissimilar welds

With the rapid growth of electric vehicles (EV), ensuring reliable and efficient joining in battery packs has become increasingly critical, particularly for dissimilar materials such as aluminum busbars and Hilumin nickel-plated steel casings. This study aims to evaluate the feasibility and performance of laser beam welding (LBW) for aluminum busbars and Hilumin nickel-plated steel casings, with a particular emphasis on the role of beam shaping. In this work, LBW was systematically investigated under different beam-shaping configurations. The weldability window was established for various process conditions, and the resulting joints were characterized in terms of morphology, mechanical performance, and electrical resistance. The results demonstrate that beam shaping significantly influences weld formation and joint quality, with distinct effects observed at different welding speeds and power levels.Correlations between peak tensile force, electrical resistance, and weld cross-sectional area were identified, highlighting the importance of process optimization for improving joint reliability. Furthermore, the influence of intermetallic compounds (IMC) on the performance of dissimilar material joints under different beam-shaping conditions was analyzed. These findings indicate that beam shaping enables the formation of more reliable dissimilar LBW joints. Overall, this work provides a technical foundation for the application of LBW in advanced battery pack manufacturing and contributes to enhancing the safety, performance, and durability of EV power systems.