Abstract: Residual stress distribution in TC2 titanium alloy thin plate welded joint and the stress relaxation effect during post-weld heat treatment were numerically simulated by using ABAQUS. Firstly, based on the simulation results of the welding temperature field of the TC2 titanium alloy thin plate, the residual stress distribution after welding was calculated, and the rationality of the simulation was verified through the measured residual stress values. Secondly, the creep model parameters of the TC2 titanium alloy were calibrated through tests to evaluate the creep effect on residual stress relaxation during post-weld heat treatment. The results indicate that during welding, the temperature in the weld zone rapidly rises to 2679 ℃, forming a quasi-steady-state temperature field. The residual stress peaks near the weld and decreases sharply with increasing distance, with a maximum Mises stress of 847 MPa. During post-weld heat treatment, the creep effect significantly reduces residual stress and improves stress distribution uniformity. With holding time prolonging, creep deformation continues in high stress regions, leading to further residual stress relaxation. However, as the creep rate gradually decreases, stress relaxation stabilizes. At the test temperature of 350 ℃, a holding time of 1-2 h results in a residual stress relaxation rate of up to 40%, after which the change slows down. Therefore, extending the holding time has a limited effect on residual stress relaxation, and in engineering applications, the holding time should be optimally controlled based on material characteristics and economic considerations.

Key words: TC2 titanium alloy plate, welded joint, welding residual stress, post-weld heat treatment, creep, residual stress relaxation