The Stress Simulation And Life Analysis Of The Dissimilar Steel Joint In Power Boilers

FEM software ANSYS is used in this paper to simulate the residual stress distribution of the G102 (12CrMoWVTiB)and SUS304(OCrl9Ni9) dissimilar steel joint, and the comparing analysis of the residual stress distribution under several different welding technics is also done. An optimization project about the welding technics of this kind of joint is presented here in the purpose of reducing the residual stress. Using the same method the working stress distribution under the actual working condition of this type of dissimilar joint is simulated. The results show that the working stress peak value appears in the HAZ of the G102 near the fusion line, fully explaining the early rupture invalidation in this part in the practice.The G102 (12CrMoWVTiB) and SUS304(OCrl9Ni9) dissimilar steel joints of some of the superheater and reheater tubes from the Huaibei power plant are cut to do the following experiments: the mechanics performance under high temperature and room temperature, metallographic structure, and the micro-rigidity distribution. The experiments' results show that the dissimilar joints have changed in structure and performance at different level comparing with the original one, and soften region has appeared in the HAZ of the G102, where the slowest rigidity falls with the augmentation of the temper parameter, and the softening rate is higher than the G102 mother material; the results also show that the mechanical strength and the slowest rigidity of all the tested joints are still higher than the G102 mother material, that is to say the joints haven't become the weak points of the system.