Effect on the Property of 2195 Al-Li Alloy Laser-Welded Joints with Different Filler Materials

Abstract

In order to improve the performance of welded joints in Al-Li alloys, butt joints consisting of 2 mm thick 2195-T8 Al-Li alloy plates are fabricated by laser beam welding with different filler wires in this paper. The joints welded by ER2319CT, ER4047, and without filler are investigated in the context of microstructure, the distribution of alloying elements, the burning loss of alloying elements, and tensile strength. From the fusion boundary to the center of the weld seam (WS), the crystal morphologies vary in the sequence of fine equiaxed grains, columnar dendrite, and equiaxed dendrite. The equiaxed grains and columnar dendrite disappear in certain areas of the WS by ER2319CT. The burning loss rates of Li and Cu in the WS by filler wires are higher than those by laser welding without filler. AlLiSi and Al2Cu are identified as the strengthening phases in the WS by ER4047, while Al2Cu, Al2CuLi, and Al6CuLi3 are the strengthening phases in the WS by ER2319CT. Compared with laser welding without filler wire, more strengthening phases improve the mechanical properties of the welded joints by filler wires. Both types of welding wires can improve the performance of welded joints, and ER2319CT is more effective.