High fracture toughness aluminum-copper-lithium sheet or light-gauge plate suitable for use in a fuselage panel

A method for producing an aluminum alloy sheet or light-gauge plate having high fracture toughness and strength, said method comprising:

• a) casting an ingot consisting essentially of 3.0 to 3.4 wt. % Cu, 0.8 to 1.2 wt. % Li, 0.2 to 0.5 wt. % Ag, 0.2 to 0.6 wt. % Mg and at least one grain refiner selected from the group consisting of 0.09 to 0.13 wt. % Zr, 0.05 to 0.8 wt. % Mn, 0.05 to 0.3 wt. % Cr 0.05 to 0.3% 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. %)<5.0;
• b) homogenizing said ingot at 490-530° C. for a duration from 5 to 60 hours;
• c) rolling said ingot to a 2 to 9 mm final gauge sheet or light-gauge plate;
• d) solution heat treating said sheet or light-gauge plate at a temperature from 490 to 530.degree° C. for a duration from 15 minutes to 2 hours, followed by quenching;
• e) stretching said sheet or light-gauge plate with a permanent set from 2.5 to 4%;
• I) aging said sheet or light-gauge plate by heating at 140-155° C. for 10 to 30 hours.

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, 0.05 to 0.13 wt. % Zr, 0.02 to 0.3 wt % Sc and optionally 0.05 to 0.8 wt. % Mn, 0.05 to 0.3 wt. % Cr, 0.05 to 0.5 wt. % Hf and 0.01 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 to 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.