Effect of welding wire composition on microstructure and properties of 5E61 aluminum alloy TIG welded joints

To study the effect of welding wire composition on the microstructure and properties of 5E61 aluminum alloy ship plates welding joints, the tungsten intert-gas (TIG) welding of 4 mm 5E61-H116 aluminum alloy ship plate was conducted using Wire-1561, Wire-5B71 and Wire-5E61 welding wires. The welded joints' surface morphology, forming quality, microstructure, and mechanical properties were analyzed. The results showed that the welding quality of the three kinds of welding joints performed well under the same welding process, and there were no visible porosities in the welding center zone. The microstructure of the welding zones was different. The grain size of the welding zone by Wire-5B71 was the smallest, followed by Wire-5E61, and the one of Wire-1561 was the largest. Due to the solution strength of the Mg element and the refined crystalline strength of Er element, the microhardness of the welding joint by Wire-5E61 performed the highest. The extension tests of welding joints have proceeded. The results showed the fracture locations of the joints were mainly located along the columnar crystal region near the fusion lines, where the microhardness displayed the lowest. The tensile strength of weld joints prepared by Wire-1561, Wire-5B71 and Wire-5E61 were 322, 323 and 338 MPa, respectively. The welding coefficients were 0.83, 0.84 and 0.88, respectively, and the elongations after fracture were 13.0%, 14.5% and 14.5%, respectively, which can meet practical engineering applications.