Study on microstructure, mechanical and corrosion behavior of Ti-6Al-4V titanium alloy by Keyhole gas tungsten arc welding

In this paper, 8 mm thick Ti6Al4V titanium alloy was successfully welded by keyhole gas tungsten electrode arc welding (K-TIG) technology without special edge preparation. The microstructure, mechanical properties and corrosion resistance of the joint were studied. The experimental results show that the overall weld is nail -shaped, and there are no welding defects such as porosity, cracks, and unfused sidewalls. The weld area is mainly composed of many fine acicular -like alpha, coarse acicular -like alpha and massive alpha intertwined with each other, and the distribution ratio of high -angle grain boundaries in the heat -affected zone and weld metal area is higher than that of the base metal. The microhardness fluctuation of each region in the welded joints is not large, and the tensile strength of the welded joints reaches 96.7 % of the base metal, and the post -weld mechanical properties are good. The K-TIG welded joints and the base metal were electrochemically analyzed, and the welded joints showed good corrosion resistance.