Compressor impeller with stress riser

A compressor impeller for use with a boreless turbocharger is provided in accordance with this invention. The compressor impeller comprises an integral hub projecting axially therefrom that includes a partial bore therein that extends from an open to a close bore end. The bore includes a threaded portion that is configured to accommodate threaded engagement with an end of a common shaft disposed through a turbocharger housing and attached at an opposite end to a turbine wheel. The hub is specially configured so that the threaded portion has a relatively increased wall thickness when compared to a remaining portion of the bore disposed between the threaded portion and the end of the bore. The bore is configured providing a section having a reduced wall thickness, between the threaded portion and the bore closed end, for purposes of providing a preferential stress relief mechanism. Configured in this manner, the compressor impeller operates to ensure that, in the event of a stress-related compressor impeller failure, the shaft will be contained in its proper placement within the turbocharger.