Study on Effect of Electromagnetic Pulse Treatment on Fatigue Life of Electron Beam Welded Joints of GH3535 Superalloy

GH3535 superalloy is an important structural material for molten salt reactors, and the heterogeneity of its welded joint can affect the overall fatigue life of nuclear energy system of molten salt reactor. In order to repair the fatigue damage of the welded joint and enhance the safety molten salt reactor in the cause of service, we treat the electron beam welded joint of GH3535 superalloy, which has been subjected to fatigue damage tests, using electromagnetic pulse technology, to investigate changes of the microstructure of the welded joint and the influence of electromagnetic pulse treatment on the fatigue life of the welded joint. Results indicate that the fatigue damage state of the welded joint is improved, and that the fatigue life under various stress levels significantly prolonged. The electromagnetic pulse treatment promote the multiplication and slip of dislocations within the welded joint, increasing the dislocation density and forming complex structures such as dislocation wall, which can hinder the propagation of fatigue cracks. Meanwhile, the electromagnetic pulse treatment impede the initiation and propagation of secondary cracks within the joints, improve the internal fatigue damage state of the welded joint, and contribute to the extension of the fatigue life of the welded joint.