Fusion boundary microstructure evolution and mechanical properties of cold metal transfer welded dissimilar A5754 and A5083 joint

Fusion boundary microstructure evolution and its effect on tensile properties of cold metal transfer (CMT) welded joint of dissimilar A5754 and A5083 is studied. Non-dendritic equiaxed fine zone (EQZ) is newly evolved and located between PMZ and weld metal zone (WMZ). The Si films are distributed as continuous layers at grain boundaries (GBs) of EQZ, these films are comparatively less and are distributed in a non continuous manner at GBs of partially melted zone (PMZ). EQZ of A5083 side exhibits finer grains than A5754 side. The narrower EQZ width, finer grains at EQZ, finer dendrites at WMZ interface and larger distribution of secondary phase particles at PMZ and heat affected zone (HAZ) increase strength of A5083 side. (c) 2020 Elsevier B.V. All rights reserved.

Automated summary

The study reveals that the tensile strength of the joint welded by cold metal transfer is higher on the A5083 side, due to finer grains in the equiaxed fine zone, narrower fusion boundary microstructure, and wider distribution of secondary phase particles.