Numerical analysis of welding residual stress for corrosion-pitted plates in marine environment‌

Aiming at the welding repair of corroded and aged plate structures in marine environments, specimens containing corrosion pits are adopted as the research object. A finite element model for the butt welding of flat plates with corrosion pits is established by means of ANSYS APDL, and the model is solved using thermo-mechanical coupling analysis. The accuracy and reliability of the proposed model are further verified through comparison with corresponding experimental results. Results show that corrosion pits change the heat transfer path in welded structures, leading to heat accumulation on one side of the weld zone. This effect is enhanced as the aspect ratio η of the corrosion pits increases. Corrosion pits raise the transverse and longitudinal residual tensile stresses by 30.60% and 24.24%, respectively, and increase the gradient between tensile and compressive stresses. With increasing aspect ratio η , the transverse residual stress increases with depth when η  < 1, decreases when η  > 1, and reaches a maximum at η  = 1. The longitudinal residual stress increases continuously in the range η  = 0.25–0.75, with the high-stress zone expanding radially around the pit. As η rises to 1-1.5, the stress peak increases, the high-stress region extends into the pit interior and wall, and the stress gradient becomes steeper. In the welding repair of corroded pit components, particular attention should be paid to deep and narrow pits with η  ≥ 1 to prevent crack propagation induced by the coupling of welding residual stress and stress concentration, thereby guaranteeing structural integrity.