An investigation on butt joints of Ti6Al4V and 5A06 using MIG/TIG double-side arc welding-brazing

An excellent butt joint of 5A06 and Ti6Al4V was achieved via MIG/TIG double-side arc welding-brazing process with Al-5Si wire. The conventional MIG welding-brazing process was carried out at the same welding heat input for comparison. Then formation and microstructure of joints were investigated, and the quality of joints was examined by tensile test. The results showed that weld formation, especially the formation of back weld, was improved obviously. The IMC layers near Ti6Al4V side were regular instead of that with a slightly serrated border near the weld, and thickness was 1-2 μm and thinner. The microstructure of the IMC layer was Al3Ti, which was more uniform. The microstructure of the weld was the Mg2Si dispersion in the α-Al matrix, which made the weld strength higher. Hence, the average of tensile strength was 250 MPa with fracture in the weld compared to 33.5 MPa with fracture in the interface by conventional MIG welding-brazing.