Investigation on pulse current-assisted stationary shoulder friction stir welded Ti-6Al-4 V joints

In this study, we investigated the effect of pulse current on the microstructure, texture, deformation behavior, and mechanical properties of Ti-6Al-4 V alloys fabricated by electrically assisted stationary friction stirring welding. With the increase of the rotation speed and peak pulse current, a lamellar structure precipitated in the stir zone became more elongated, resulting in a higher concentration of grain orientation distribution and a larger but gradually decreasing ratio of high-angle grain boundaries. Moreover, the texture strength increased, but still remained lower than that of the transition zone on both sides. The microhardness distribution of the welded joint was anisotropic in all layers, with the stir zone exhibiting the highest hardness, while the HAZ was identified as the weakest region. The joints have a maximum tensile strength of 1020.1 MPa and an elongation of 6%, respectively. The tensile strength is comparable to that of the base metal (BM), and the elongation reaches 57.7% of BM. This improvement is mainly attributed to grain refinement and uniformly distributed hardness. Furthermore, all tensile fractures were ductile fractures.