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

Ti-6Al-4V titanium alloy weldments were prepared using 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 shrinks gradually, and the weldment fusion zone (FZ) width and heat-affected zone (HAZ) width are reduced by 18.2% and 31.3%, respectively. The molten pool intensive stirring effect and the heat input reduction by FFDP TIG waveform resulted in the prior beta grain size decreased by 55.6% and the refinement of martensite alpha MODIFIER LETTER PRIME structures. Microhardness and 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 the FFDP-TIG process improves the Ti-6Al-4V weldment microstructure and mechanical properties and can perform excellently in practical applications.