Influence of preset gap on strength and failure mode of steel/aluminum CMT joint

The strength and failure mode of dissimilar materials joint between galvanized low carbon steel and aluminum alloy made by cold metal transfer (CMT) welding process were investigated. In order to enlarge the bonded area of brazed joint, preset gap was introduced between steel and aluminum alloy during CMT welding processing by means of feeler. It is found that the shear strength of steel/aluminum CMT welded joint could be improved with increasing of preset gap because the length of bonded line was improved. When I he preset gap was increased to 0.5 mm, brittle fracture occurred at the interface layer between steel and aluminum due to the existence of remained zinc at the weld toe.