Comparative effects of Al-Si and galvannealed coatings on the properties of resistance spot welded hot stamping steel joints

Al-Si coated and galvannealed (GA) hot stamping steels were resistance spot welded, and the welding current, properties and mechanical performance of the joints produced were compared. The coating significantly affected the welding current required for attaining the conventionally acceptable weld fusion zone size of 4t, and the welding current range. The coating also influenced the energy absorption and failure mode transition but had no effect on the peak failure load provided the stack consisted of sheets having similar coating. For dissimilar combination of Al-Si and GA coated sheet stack, the joint mechanical performance was significantly deteriorated.