Patent ID: 7744704

Claim:
A method for producing an aluminum alloy sheet or a light-gauge plate having high fracture toughness and strength, said method comprising: a) casting an ingot consisting essentially of 2.7 to 3.4 wt. % Cu, 0.8 to 1.4 wt. % Li, 0.1 to 0.8 wt. % Ag, 0.2 to 0.6 wt. % Mg and at least one grain refiner selected from the group consisting of 0.05 to 0.13 wt. % Zr, 0.05 to 0.8 wt. % Mn, 0.05 to 0.3 wt. % Cr 0.05 to 0.3 wt % Sc, 0.05 to 0.5 wt. % Hf and 0.05 to 0.15 wt. % Ti, remainder aluminum and unavoidable impurities, with the additional proviso that the amount of Cu and Li is such that Cu(wt. %)+5/3 Li(wt. %)<5.2; b) homogenizing said ingot at 490-530° C. for a duration from 5 and 60 hours; c) rolling said ingot to a sheet or a light-gauge plate with a final thickness from 0.8 to 12 mm; d) solution heat treating and quenching said sheet or light-gauge plate; e) stretching said sheet or light-gauge plate with a permanent set from 1 to 5%; f) aging said sheet or light-gauge plate by heating at 140-170° C. for 5 to 30 hours.