Abstract: A composite compressor wheel for turbochargers and the like comprises a cast shell having aerodynamically contoured centrifugal impeller blades and a hub section defining a generally conical recess into which a hub insert of noncast material resistant to stress failure is secured as by inertia welding. In use of the composite wheel, the hub insert substantially occupies high stress regions within the wheel to improve wheel fatigue life.

Abstract: A cast austenitic stainless steel bushing for relatively high temperature turbocharger and automotive applications is provided having good hot hardness and hot strength properties and a co-effficient of thermal expansion approximating that of the parent housing alloy. Bushings made of this alloy have a composition in the range of 29-32% chromium; 4-8% nickel, 1.0-1.5% columbium and tantalum; 1.3-1.7% carbon, 0.25-0.45% sulfur, 0.3-0.4% nitrogen, up to 1.0% manganese, up to 1.0% silicon, up to 1.0% molybdenum, up to 0.1% phosphorous, balance iron.