Study on arc shape, weldment microstructure and mechanical properties of Ti-6Al-4V welded by FFDP TIG waveform

Abstract Ti-6Al-4V titanium alloy weldments were prepared by the conventional TIG and fast frequency double pulse TIG (FFDP TIG) waveforms. Arc shape, microstructure and mechanical properties of weldments were investigated. The arc core area of the FFDP TIG shrink gradually, the weldment fusion zone (FZ) width and heat affected zone (HAZ) width reduced by 18.2% and 31.3%. The molten pool intensive stirring effect and the heat input reduction by FFDP TIG waveform, resulting in the prior β grain size decreased by 55.6% and refinement of martensite αʹ structures. Microhardness, tensile strength of FFDP TIG weldment were higher than that of conventional TIG, the tensile strength and elongation reached 98.4% and 65.6% of the base metal, respectively. The results show that FFDP-TIG process improve the Ti-6Al-4V weldment microstructure and mechanical properties and can exhibit excellent performance in the practical applications.