EFFECT OF ELECTRODE GEOMETRY ON RESISTANCE SPOT WELDING OF AHSS

The implementation of advanced high strength steels (AHSS) into the automotive industry offers distinct advantages relative to achieving light weighting goals and improved structural performance. The challenge for the automotive industry is a need to develop the processes and know-how to implement these new materials into their product economically. Currently the primary method used to develop spot welding practices for new material involves both extensive and costly laboratory trial and error experimentation. The finite element method was used as a low cost alternative for the fundamental development of joining practices for AHSS. Specifically, the effect of electrode geometry on nugget formation in typical AHSS resistance spot weld applications was investigated. The weld joint chosen for the study was based on an Auto-Steel Partnership (A/SP) state-of-the-art B-Pillar to rocker joint using 1.6 mm GI DP780 to 1.6 mm GI DP780 (B pillar reinforcement to rocker outer reinforcement). The effect of electrode cap geometry was modeled using SORPAS® resistance spot welding FEA software. The results were verified experimentally at the University of Waterloo Centre for Advanced Materials Joining.