Characteristics of welding distortion and residual stresses in thin-walled pipes by solid-shell hybrid modelling and experimental verification

Welding distortion in thin-walled pipes is a prominent and common problem, deteriorating the dimensional accuracy and even increasing the failure risk. The objective of this study is to improve our understanding of welding behaviors and mechanism of thin-walled pipes and thus provide reference for developing control schemes. A solid-shell hybrid model was developed to analyze the characteristics of welding distortion and re-sidual stress distribution with improved modelling and calculation efficiency. The hybrid modeled results agreed well with the experimental measurements and conventional full solid model. It was observed that the welding deformation in seam-welded pipes presents a combined form incorporating convex bending on the circumstance and axial bending toward the weld side besides the shrinkage in both directions. The maximum distortion was observed in the two ends of weld line. Self-restraint characteristics of pipe structures were clarified by analytical solutions to analyze the bending distortions in both hoop and axial directions. For welding residual stresses, the axial stress near the weld line was high tensile stress, and the value on the inner surface was slightly larger than the outer one. The hoop stress near the weld was compressive on the outer surface and tensile on the inner side with similar magnitude. The correlation between welding inherent deformation components and pipe diameter was further clarified using the proposed hybrid model. Effect of shell element percentage and size on simulated results was also discussed to provide a reference for the application of the solid-shell hybrid model.