Effect of activating flux on penetration and microstructure of tungsten inert gas-welded pure titanium grade-2 plate

Activating flux tungsten inert gas (A-TIG) welding has drawn intense research focus in the present material era to overcome the wide bead geometry and shallow penetration of conventional TIG welding. This work is devoted to investigating the role of halide-based flux on the bead geometry and the microstructural evolution of 7-mm-thick pure titanium plates. Square butt joints were made in the bead on plate configuration by varying arc current in the range of 80–150 A. Halide flux was proven to be effective in narrowing down the bead geometry and increasing the penetration up to 244%. Full penetration was obtained at 150 A, while the maximum penetration was 3.2 mm without flux. The fusion zone microstructure consisted of plate-like α grains and residual β grains. Many grains were filled with lamellar α structure. The microstructure of the fusion zone with and without activating flux showed a similar kind of structure. The hardness of the fusion zone was found to be 25–30% higher to that of base metal. The hardness distribution with and without activating flux was in the same range.