Failure Analysis on Fracture of Impeller Blades of High-speed Centrifugal Aircompressor

Impeller blades of high-speed centrifugal aircompressor fractured during operation process, and failure reasons was investigated by means of visual examination, chemical compositions analysis, mechanical properties testing, SEM observation, EDS analysis and metallographic examination. The results show that the main cause for fracture failure of the compressor blades was due to the high speed aluminum particles. The particles came from inter-stage cooler fins because of poor shell fluid layout design. A thick fouling layer was formed on the surface of the blades by the aluminum particles which brought about high frequency fatigue load to the opposite located blades and cracks initiated on the tip of the blades. Therefore the blade failed due to high frequency fatigue and fretting wear. The low impact toughness of the blade material also accelerated the crack propagation.