Generation and distribution mechanism of welding-induced residual stresses

Welding-induced residual stresses (WIRS) can have influence on the performance and service life of the welded structures. The present study experimentally and numerically investigates the reason and mechanism behind the generation and distribution of WIRS concretely. The results show that the thermal shrinkage process and phase transformation process are the main sources generating welding-induced longitudinal residual stress (σ_L^RS). Nevertheless, except for these two processes, the quenching process would be another source producing transverse residual stress (σ_T^RS). In the current work, it is found that the maximum σ_L^RS generally reaches the yield strength (σ_y) of base metal (BM) at ambient temperature (T_RT) for both transforming and non-transforming materials but located at different areas. In the single-pass weldments without external restraint, σ_T^RS profile on the top surface is usually always M-shaped for the non-transforming materials but W-shaped σ_T^RS instead for the transforming materials. The distribution mechanism behind the M-shaped or W-shaped profile is systematically clarified here.