Patent ID: 8728258

Claim:
A method of using a multiple step artificial aging process for an automotive engine component made from an aluminum silicon alloy casting comprising relatively thick regions and relatively thin regions, the method comprising: a) solution heat treating the casting to dissolve alloying elements, following by cooling; b) rapidly heating the casting to a nucleation temperature in a range of 400° F. to 500° F. at a rate of at least 1.5° F./min such that a heating rate differential between the relatively thick regions and relatively thin regions is no greater than 7° F./min, and holding at a temperature at least equal to the nucleation temperature for a time sufficient to induce nucleation throughout the casting; c) cooling the casting to a temperature about 100° F. or more lower than the nucleation temperature, d) heating the casting to a temperature lower than the nucleation temperature to facilitate growing precipitates as distinct phase in the casting, and e) cooling the casting to ambient temperature.