Abstract: TA2 titanium plate was welded by argon arc welding, and the microstructure and mechanical properties of the as-welded and post weld heat treated joint were compared and analyzed. The results show that the weld zone width of the TA2 titanium plate argon arc welded joint is about 6 mm, and the heat affected zone width is about 4 mm, the microstructure of the weld zone is mainly composed of β equiaxed crystal, internal acicular α martensite and small amount of α′ martensite, and the microstructure of the heat affected zone is mainly composed of α lath grains. The maximum hardness of the weld zone is about 195 HV0.5, the resistivity is higher than that of base metal, and the residual stress is the largest, such as the transverse and longitudinal residual stresses reach 500 MPa and 225 MPa, respectively. When post weld heat treated at 550 ℃, the grain size of the weld zone is basically the same as that of the as-welded ones, the grain size of heat affected zone is significantly smaller, the hardness of welded joint is significantly increased, and the resistivity and residual stress are reduced. When post weld heat treated at 600 ℃, the grain size, hardness and resistivity of the welded joint are basically the same as that of the as-welded ones, and the residual stress is significantly reduced. When post weld heat treated at 650 ℃, the grain size of welded joint grows significantly, while the hardness and resistivity decrease, and the residual stress decreases significantly.

Key words: argon arc welding, titanium alloy, post weld heat treatment, microstructure, mechanical properties