Many studies over the last three decades have been made to estimate the remaining life of superalloys components focusing on crack propagation behavior.Summarizing the fatigue fracture characteristics in single crystal and directional solidified Ni-base superalloys,the crystallographic slip planes play an important role,and they reveal the typical features of Stage Ⅰ fatigue crack propagation on crystallographic slip planes at lower and intermediate temperatures.Whilst some efforts based on the fracture mechanics have been made to interpret the Stage Ⅰ crack propagation,the issues are not yet fully understood.