Failure analysis of a turbo-disk

A failure investigation has been conducted on the turbo-disk used in a locomotive turbochanger, which is made from GH2132 high-temperature alloy. The fracture of three teeth and the crack of 11 teeth took place, which mainly occurred at the third root near the groove. Fractographic studies indicate that the crack originated at the root and propagated along the turning direction of the turbo-disk. In the initial crack propagation zone several different failure mechanisms performed successively, which are the intergranular corrosion crack, the corrosion-fatigue propagation and the dimple fracture. The greater bending stress on the tooth root and the presence of the corrosion medium in the service circumstance should be responsible for the failure of the turbo-disk.