Fatigue crack simulation of the 316L brazed joint using the virtual crack closure technique

Abstract The brazed joint has been widely used in the plate-fin structure, and the periodic pressure suffering in operation makes it very important to ensure the fatigue strength. This paper investigates the fatigue crack growth of 316 L brazed joint by experiments and simulations. Firstly, the mechanism of the fatigue crack growth behavior is analyzed via the scanning electron microscope (SEM) and the electron back-scattered diffraction (EBSD) techniques. Then, the virtual crack closure technique (VCCT) is adopted to simulate the fatigue crack propagation by developing a user subroutine. Lastly, the effect of filler metal thickness on strain energy release rate is discussed. Results show that the fatigue crack mainly propagates along the interface of the base metal and filler metal. However, the crack is still located at the filler metal and follows a transgranular fracture mode. In addition, the simulated results by VCCT agree well with the experiment, which demonstrates the feasible application of VCCT for brazed joint fatigue crack simulation. Besides, the strain energy release rate of the brazed joint has an intrinsic different mechanism compared with the base metal and the filler metal, and the strain energy release rate decreases with the filler metal increasing.