Failure analysis on connection components of turbo-disk and main-shaft used in a locomotive turbocharger

Three bolts, three pins connecting turbo-disk and main-shaft and the navel of turbo-disk fractured during servicing, which were used in a locomotive turbocharger. Examination and analysis results show that one of location pins was not riveted into the pin hole on the plate of the main-shaft due to dislocation. The pin encountered greater hammering force and resistance to moving downward when being riveted into the hole, so corresponding impact tensile load was exerted on opposite bolt and the navel. The cracks initiated at the last engaged thread root of the bolt and the root fillet of navel and propagated in fatigue mode under the action of alternative loads. The bolt and the navel fractured first. Other components fractured in succession. Defective operation of riveting is responsible for the fracture of connection components.