Abstract

An investigation on a failed turbocharger turbine blade

Author(s): Nader El-Bagoury

A failure analysis of a turbocharger blade made of Ni base superalloy is presented in this case study. Localized remelting of eutectic structure due to overheating during operating is the main cause for the failure. The  precipitates at the blade’s root, cold reference zone are fine compared to the coarse  particles found close to the crack area. Micro-cracks initiated in interdendritic regions due to the reduction of strength in these areas because of overheating. The weakenedmicrostructure andmechanical stresses caused by vibration, centrifugal forces and bending moments caused fatigue as evidence by, beach marks and tear ridges on the fracture surface. The fatigue failure is the prevailing mechanism of fracture failure in airfoil section.


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