Shear strength of CMT brazed lap joints between aluminum and zinc-coated steel

Abstract

Higher shear strength and fusion line failure were measured in CMT brazed lap joint of aluminum alloy 6061 and zinc coated steels with high strength (DP600) or thick plate (1.2mm). Lower shear strength and interface failure were observed only if aluminum was brazed with low strength (270MPa) and thin steel sheet (0.7mm). A numerical model was developed for the prediction of shear strength and failure modes of the CMT lap joints. The maximum principle stress and deformation energy at the interface layer of the CMT joints were adopted as failure criteria for interface failure prediction. The equivalent plastic strain in the weld metal, HAZ and base metal of aluminum side of the CMT brazed joints was used as a criterion for failure prediction occurred on the fusion line. The shear strength of CMT joints and the two failure modes can be accurately estimated by the developed numerical model.