Microstructural and mechanical characterization of aluminum-lithium alloy 2060 welded by fiber laser

In this study, with constant welding parameters, butt joints consisting of 2.0 mm thick 2060-T8 Al-Li alloy have been fabricated by laser beam welding. A fiber laser using eutectic alloy AA4047 filler wire was employed. The joints' microstructural evolution and the effects of strain rates on the joints' mechanical behaviors were researched. Standard tensile specimens extracted from the welded plates were tested at room temperature with strain rates ranging from 10−4 to 10−1 s−1. Extensive microhardness measurements were also conducted to investigate the relationships between strain rates and microhardness distributions after fractured. It was found that solute segregations of Si and Cu occurred in the grain boundaries in the heat affected zone and fusion zone. Mechanical properties and fracture morphology showed close relationships with the tensile strain rate. The nondendritic equiaxed zone was the minimum hardness and weakest region on the whole joint.