Strength of resistance spot welding of aluminum alloy AA6061 to carbon steel using different filler materials

Abstract

Resistance spot welding is a process in where contacting metal surfaces for similar or dissimilar materials are joined by heat generated from resistance to electric current. Carbon steel and aluminum alloy A6061 sheets were welded by using resistance spot welding method in two stages with and without filler materials where copper and zinc were implemented as fillers, where those two materials, particularly the former, has acceptable affinity, therefor better wettability, to both welded metals. The characteristics of weld joint were investigated by measuring the effect of welding current and time on the nugget size and tensile shear strength of the weldment. The results showed that the welding current has an incremental influence on both the nugget size and tensile shear strength for the two cases studied. Also, the results revealed that the copper filler increases the strength of the weldments more than the zinc filler, which is attributed of higher affinity of the copper to both metals. The joint with the maximum tensile shear strength of 47 kN/m2 is obtained at the condition of 15 kA welding current for copper filler and 40 kN/m2 is obtained at the condition of 13 kA. The thickness of interfacial reaction layer decreased from central joints region to the surrounding area.