Process for making a turbine wheel and shaft assembly

摘要

A process for making a turbine rotor includes steps of providing a shaft made of a first metal composition and having an integral pin projecting axially therefrom, providing a mold that defines a cavity for investment casting a turbine wheel, disposing the pin within the cavity of the mold, pre-heating the mold and the pin to a mold temperature, pouring a molten second metal composition into the cavity of the pre-heated mold such that the molten second metal composition envelopes the pin within the cavity, and controlling the process so that the pin acts as a chill member causing the second metal composition around the chill member to solidify with a finer equiaxed grain structure than would be the case without the chill member. The turbine wheel is joined to the shaft via the casting of the turbine wheel about the pin.