Microstructure and properties of Ti–6Al–4V alloy welded joint by keyhole gas tungsten arc welding

In this paper, 12 mm Ti6Al4V titanium was successfully welded in a single pass using the keyhole gas tungsten arc welding technology, without special edge preparation or the addition of a filler material. The microstructure and properties of the welded joint are studied. The microstructure of the joint was classified and characterized in detail according to the difference of the effect of welding thermal cycle, and the difference of the top, middle and bottom microstructure of the joint was compared and analyzed. The microhardness of transverse joint fluctuates in the range of 50HV0.2. The difference of longitudinal microhardness is about 100HV0.2. The lowest is 280 HV0.2, and the highest is 378 HV0.2. The tensile strength of the joint reaches 925 MPa. The fracture position of the joint is located in the base metal. The Charpy impact energy of the weld center reaches 50J, which is 56% higher than that of the base metal 32J, and the weld metal shows good toughness.