The effects of different weld zone characteristics on mechanical properties and fracture behavior of MIG welded 5754, 5083, and 6082 aluminum alloys

Abstract

In this study, the mechanical properties and fracture characteristics of metal inert gas (MIG)-welded joints of 5754, 5083, and 6082 aluminum alloys were studied by comparing weld microstructure. ER5356 was utilized as the filler material for the welding process, and the effects of using ER4043 as a common filler material specifically for 6082 alloy were investigated. Mechanical tests including tensile, microhardness, and bending tests were conducted on the welded joints. Microstructural investigations were performed using optical and scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The microstructure of the weld zone in each sample and the effects of their characteristics on the mechanical properties of the joint such as its hardness and strength were investigated. The results reveal that 5754 alloy plates welded with ER5356 exhibited a 15% reduction in elongation along with decreases of 23 and 24 MPa in the yield strength and ultimate tensile strength (UTS), respectively, compared to the base material. In contrast, welding 5083 base material with the same filler led to a 35% reduction in elongation and 50 and 70 MPa reduction in the yield strength and UTS, respectively, relative to the base material. In this case, using ER4043 resulted in solidification cracks at the grain boundaries and shrinkage cavities in the weld zone because of Si segregation in the interdendritic spaces, which may have contributed to the degraded mechanical properties observed during the welding of 6082 alloy in this study.