Patent ID: 7993474

Claim:
A naturally aged wrought sheet or plate product from 1 to 16 mm thick that has been treated with a solution heat treatment, quenching and cold strain-hardening, and possesses a permanent set between 0.5% and 15%, and that is clad on at least one face thereof with an alloy in the 1xxx series and further comprising an AlCuMg type alloy wherein Zn is added to said alloy in a certain controlled quantity to provide the following composition (% by weight): Cu 3.80-4.30; Mg 1.25-1.45; Mn 0.35-0.50; Zn 0.5-1.10; Fe<0.10; Si<0.10; Zr ≦0.05; Ag<0.01 other elements <0.05 each and <0.15 total, remainder Al, and wherein the galvanic corrosion current of said clad sheet or plate product is not more than 2.5 μA/cm 2 for an exposure of a riveted assembly to a corrosion test up to 200 hours, in which the cladding alloy is placed in a cell containing a solution of AlCl 3 (0.02 M, deaerated by nitrogen bubbling) and the core alloy placed in a cell containing a solution of NaCl (0.02 M, aerated).