Process for obtaining high ductility high strength aluminum base alloys

A process for the preparation of aluminum having high strength and high ductility, comprising:

• A. providing an aluminum base alloy containing from 0.05 to 1.0% iron, from 0.05 to 1.0% silicon, at least one material selected from the group consisting of less than 10.0% magnesium, less than 3.0% manganese, less than 1.0% copper, less than 0.5% chromium, less than 0.5% zinc, less than 0.5% zirconium, less than 0.5% titanium, less than 0.1% boron, others less than 0.5% each, total less than 1.5% balance essentially aluminum;
• B. working said alloy, preferably by rolling or drawing, at a temperature between 450.degree.F and 950.degree.F with a total reduction in excess of 20%;
• C. working said alloy, preferably by rolling or drawing, at a temperature below 450.degree.F with a total reduction in excess of 20%;
• D. holding said alloy at a temperature of from 250 to 650.degree.F for a period of time no greater than defined in the following formula:
• T (8.95 + log t) = 5,700, wherein T is temperature in degrees Kelvin and t is the maximum time in minutes at temperature T, so that there is no recrystallization throughout the matrix and so ther there is less than 10% loss in tenxile strength;
• and
• E. repeating step C, thereby resulting in an alloy having a subgrain size of less than 0.001 mm with the subgrain walls being formed of pinned dislocation tangles.