Patent ID: 7018489

Claim:
A method of artificially aging an aluminum alloy product to achieve a property in the product wherein the value of the property varies in response to aging, the method comprising: heating an aluminum alloy product over an aging period which includes a time period during which the product is in an underaged state and terminating the aging period when the property is achieved according to a mathematical formula evaluated for each temperature regime experienced by said product, wherein said mathematical formula is a time- and temperature-dependent expression of the property comprising at least two time-domain and temperature-domain evolving variables, and wherein the product is optionally age formed and, wherein the property is tensile yield strength and said time and temperature-domain evolving variables are X s and X b and wherein said time- and temperature-dependent expression of the property comprises X ( t,T )= X s −βX b wherein X is a normalized value of strength and β is a constant for the alloy and X is solved from the following equations: ⅆ Y s ⅆ t ⁢ n s ⁢ K s 1 / n s ⁢ Y s 1 - 1 / n s ⁢ ⁢ where ⁢ ⁢ Y s = ln ⁡ ( 1 1 - X s ) ; ⅆ Y b ⅆ t ⁢ n b ⁢ K b 1 / n b ⁢ Y b 1 - 1 / n b ⁢ ⁢ where ⁢ ⁢ Y b = ln ⁡ ( 1 1 - X b ) ; K s = K s o ⁢ exp ⁡ ( - Q s RT ) ; K b = K b o ⁢ exp ⁡ ( - Q b RT ) ; and wherein K x″ , K b″ , Q s , Q b , n s and n s are constants for the alloy.