Patent ID: 6074501
Filing Date: 2000-06-13
Classification: C22C,C22F

Abstract:
A method of increasing the tensile strength at 300.degree. C. of an aluminum alloy casting, said casting consisting essentially, by weight, of 4 to 20% silicon, aluminum, 0.1 to 2% magnesium as a required hardening constituent and 0 to 4% copper, 0.2 to 2% iron, 0 to 3% nickel as optional hardening constituents, the microstructure of said casting comprising aluminum dendrites, silicon particles and hardening particles containing magnesium and said other hardening constituents if present, said method comprising(a) heating the casting to a temperature of about 500.degree. C. to 540.degree. C. to redissolve at least some of said hardening particles and to redistribute uniformly the redissolved constituents throughout the aluminum dendrites,(b) transferring the casting to a temperature regime in the range of 350.degree. C. to 450.degree. C. and holding the casting in said regime for a period to reprecipitate hardening particles throughout the aluminum dendrites, and(c) cooling the casting to ambient temperature.