Abstract: The crack and fracture of blades made of a directionally solidified superalloy were analyzed. The failuremode and cause were studied in virtue of fracture observation and metallographic structure analysis. The results showthat the crack and fracture on the superalloy blades have the same failure mode resulting from surface recrystallization. Owing to the plastic deformation at the blade surface, recrystallization formed during the solid solution heattreatment . Before blade application, the recrystallization zone is already exist on its two sides and surface.

Key words: directionally solidified superalloy, blade, recrystallization, fatigue failure