Failure Reason of the Blade of Top Gas Energy Recovery Turbine

Cracks were found in the first and second stage rotor blade root section of a wet-typed top gas energy recovery turbine (TRT) after operation for 3 a. In order to investigate the cause for cracks, the failure analysis of the blade was performed by macroscopic morphology observation, chemical composition analysis, tensile property test and microscopic morphology observation. The results show that the blade failure was a typical corrosion fatigue damage. The cracks were located in the middle of the first tenon of the blade root. The cracks were initiated from corrosion pits on the contact surface of blade root and shaft groove. Under the effect of complex alternating stress, cracks propagated further, which eventually led to the abnormal vibration and the shut-down of the TRT.