Patent ID: 8333853

Claim:
A method comprising: (i) preparing a 2199 aluminum alloy for artificial aging, the preparing comprising: a. solution heat treating the 2199 aluminum alloy at a temperature of at least 800° F.; and b. quenching the 2199 aluminum alloy; and (ii) artificially aging the 2199 aluminum alloy, the artificial aging comprising: c. aging the 2199 aluminum alloy at a temperature of at least 250° F.; and d. final aging the 2199 aluminum alloy at a temperature of from 165° to not greater than 225° F. and for a duration such that the 2199 aluminum alloy realizes: (1) at least a 3% increase in tensile yield strength as compared to a similar aluminum alloy; and (2) better fatigue crack growth resistance as compared to the similar aluminum alloy; wherein the artificial aging step (ii) is completed such that the volume fraction of delta prime phase within the 2199 aluminum alloy increases during the final aging step, and wherein the claimed tensile yield strength increase and better fatigue crack growth resistance properties are realized due to such increase in the volume fraction of the delta prime phase; wherein the similar aluminum alloy is of identical composition relative to the 2199 aluminum alloy; wherein the similar aluminum alloy and the 2199 aluminum alloy are prepared identically for artificial aging; and wherein the similar aluminum alloy is artificially aged in the same manner as the first 2199 aluminum alloy, but in the absence of the final aging step (ii)(d).