Distribution and relaxation of welding residual stress in U-rib-to-deck joints considering actual material properties

Welding residual stress (WRS) adversely affects the fatigue cracking of U-rib-to-deck joints. The distribution and relaxation of the WRS of a U-rib-to-deck joint were calculated and analyzed by combining measurement and simulation and considering the inhomogeneity of the material. First, the initial WRS was simulated by using the actual high-temperature material properties of the base metal (BM) and weld metal (WM), and the simulation value was verified against measured data. Second, based on the simulated initial WRS, its relaxation was simulated using the Chaboche cyclic-plasticity constitutive model of BM and WM, and the influence of cycle number, stress amplitude, and stress ratio on WRS relaxation was investigated. The results show that the WRS relaxation changes its value but not its distribution trend. Most of the WRS relaxation occurs in the first cyclic loading, accounting for approximately 90% of the total relaxation. The relaxation increases with cycle number increasing until a stable state is reached after between seven and ten cycles. The WRS relaxation increases with stress amplitude or stress ratio increasing. Finally, a predicted equation for WRS relaxation was proposed based on the cycle number, stress amplitude, and stress ratio.