Microstructural and Mechanical Characteristics of 7075-T6 Aluminum Alloy Joint by Double Wire Pulsed Cold Metal Transition Welding

Abstract

In order to solve the problems of low joint strength and poor welding efficiency in fusion welding of 7075-T6 aluminum alloy, the double wire pulsed cold metal transition (DW-CMTP) welding method was used to weld 7075-T6 aluminum alloy. The microstructural and mechanical characteristics of the joints were analyzed by energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), tensile test and Vickers hardness measurement. The results showed that the DW-CMTP welded joints had good mechanical properties. The highest tensile strength of the joint is 320 MPa without post-weld heat treatment, reaching up to 63% of the basic material. The presence and distribution of micropores in weld joint were manipulate by welding parameters and weakened the joint strength. The fracture location transferred from the heat-affected zone to the fusion zone with the increase of heat input, owing to the change of pore distribution.