How ultra high frequency of pulsed gas tungsten arc welding affects weld porosity of Ti-6Al-4V alloy

Ultra high frequency of pulsed gas tungsten arc welding (UHFP-GTAW) has been considered as a promising method to improve weld quality of titanium alloys. This paper studies the effect of UHFP-GTAW on weld porosity of Ti-6Al-4V alloy, which shows how liquid pressure/viscosity/temperature of molten pool influences nucleation, growth, detaching, and escaping of gas pore. Results indicated that compared to conventional GTAW, the liquid pressure and curvature radius of the gas pore were increased significantly while viscosity and filtration angle of the gas pore reduced simultaneously caused by UHFP-GTAW, leading to high escaping speed and easy detaching process of the weld gas pore. It is suggested that the elimination of weld porosity of Ti-6Al-4V alloy can be achieved by UHFP-GTAW process.