Method for producing fine-grained, high strength aluminum alloy materials

An aluminum alloy material having a high strength, small grain size, good resistance to stress corrosion cracking and very high degree of workability is produced from an aluminum base alloy consisting essentially of 5.1 to 8.1 wt. % Zn, 1.8 to 3.4 wt. % Mg, 1.2 to 2.6 wt. % Cu, up to 0.2 wt. % Ti and at least one of 0.18 to 0.35 wt. % Cr and 0.05 to 0.25 wt. % Zr, the balance being aluminum and impurities by an improved production method described in detail in the disclosure. The improved method is particularly characterized by a special annealing step in a continuous annealing furnace under the application of a tension not exceeding 2 kg/mm2 to a coiled alloy sheet to be annealed, the annealing including rapid heating of the coiled alloy sheet to a temperature of 4000 to 5000 C. at a heating rate exceeding 500 C./min