Fracture reasons of three stage rotor blade of engine compressor

The blade of compressor three stage rotor of an engine fractured. The fracture reasons were analyzed by means of macroscopic observation, chemical composition analysis, scanning electron microscope and energy spectrum analysis, metallographic examination, hardness test and blade vibration modal analysis. The results show that the fracture property of the blade was fatigue fracture, and the fatigue originated from the corrosion pit about 0. 8 mm from the inlet side of the vane concave surface. Corrosion pits reduced the fatigue resistance of blades, which was the main reason for fatigue fracture of blades. The blade had 11 order resonance in the working speed range, which caused the initiation and propagation of fatigue cracks in the blade.