Welding residual stresses'’ effect on the performance of a pressure-resistant ring-ribbed cylindrical shell made of dissimilar titanium alloys

This study investigates the impact of welding residual stresses on the performance and ultimate strength of deep-sea pressure-resistant structures. Residual stress distributions are quantitatified using sequentially coupled finite element simulations of K-TIG welding applied to a cylindrical structure composed of TC4 shell and TA17 stiffener. The results show that peak longitudinal tensile stresses in the heat-affected zone reach approximately 570–580 MPa, while transverse compressive stresses locally exceed 300 MPa, indicating a highly non-uniform residual stress field. Post-weld heat treatmentsignificantly reduces these stresses, lowering the maximum tensile residual stress to about 100 MPa and effectively eliminating most compressive stress concentrations. Incorporating residualstresses field into nonlinear buckling analysis further demonstrates that heat treatment yields a measurable improvement – though limited – in the ultimate external-pressure capacity of the ring-stiffened cylindrical shell. These findings underscore the importance of accurate residual- stress modeling and optimizing heat-treatment parametersfor structural integrity and reliability in deep-sea applications.