Finite Element Simulation and Residual Stress Analysis of the Whole Process of Metal Bellows Forming

In this study, the whole process finite element simulation of metal bellow welding and post-weld bulging process is performed. The distribution of the temperature field and post-weld residual stress field during welding as well as the residual stress after tube bulging was discussed. The residual stress of the formed metal bellows was detected using the x-ray diffraction method, and the simulation accuracy was verified. Results show that the peak temperature of the weld center is 1551 & DEG;C, whereas that of the heat-affected zone is half of that of the weld zone. The uneven welding temperature caused local thermoplastic deformation, leading to a large welding residual stress with a maximum value of 231.6 MPa. During bellow bulging, the base metal area at the trough produces large plastic deformation due to the extrusion of the punch and a large residual stress is generated after the mold is unloaded. The residual stress generated after the bulging of the weld zone at the trough and the welding residual stress cancel each other out, such that the weld zone at the trough has a low peak residual stress and high fatigue strength.