Influence of Temperature Distribution to Residual Stress of Multi-layer Welding of Semi-automatic Swing Welding in X80 Steel

In practice, weld passes undergo different thermal cycles for self-shielded flux-cored wire of semiautomatic welding. Numerous experiments show that the residual stress of welded joints is complex and the distribution of it would be affected by the different thermal cycles of each welding pass. In this study, the thermal cycle curves of swing welding are simulated by SYSWELD welding software, and the relative error between experimental and simulated thermal cycle curves is approximately 1.2% to 7.3%. Results show that the peak temperature decreases with increasing distance from heat source. As the distance from the heat source changes from 3.0 mm to 5.1 mm, the cooling times t8/5, t8/3, and t6/3 are increased by 1.5 s, 5.5 s, and 6.3 s, respectively. The transverse residual stress of the welding plate exhibits great variation during welding, but the longitudinal residual stress changes insignificantly. With the increase in weld passes, the transverse and longitudinal residual stresses of the center surface of welded joints decrease apparently. The transverse and longitudinal residual stresses are reduced by 300 Mpa and 310 Mpa, respectively. © 2019, Science Press. All right reserved.