Research on low-cycle fatigue behavior of Ni-based single crystal superalloy with shaped film cooling holes at high temperature

Film cooling holes (FCHs) geometric structure significantly affects low-cycle fatigue (LCF) of the single crystal turbine blade. This study investigates the LCF behavior of Ni-based single crystal plate specimens with two different structure FCHs, including elliptical and fan-shaped FCHs, by high temperature fatigue tests and crystal plasticity simulation. The results show that the LCF life of the fan-shaped FCHs is shorter than those of the elliptical FCHs. The fracture characteristics and microstructure evolution of different structure FCHs are dissimilar. Oxidation affects the fatigue crack nucleation process at the FCH edge. The resolved shear stress (RSS) around fan-shaped FCHs is greater than elliptical FCHs under one cyclic stress, and the area with larger RSS is consistent with fatigue crack nucleation position. The early LCF failure is mainly attributed to the high temperature oxidation of the local slip deformation induced by RSS concentration around the FCHs.