PURPOSE: To obtain a high strength aluminum alloy which is improved in its mechanical property in the direction of wall thickness, toughness, etc., by processing an aluminum alloy ingot containing Cu, Mg, Mn and impurity by means of a hot working after it is treated with a homogenization treatment, a cold working in a degree of more than specified rate, and then a solution treatment.

CONSTITUTION: An Al alloy ingot which contains 2.8W5.0% of Cu, 1.2W2.0% of Mg, 0.2W0.9% of Mn, and the rest composed of impurity and Al, is prepared. But Fe and Si contained as the impurity are limited to less than 0.15% and 0.1%, respectively. The Al alloy ingot is processed by means of a hot working and its cast structure is converted into a working structure after its inner structure is homogenized by a homogenization treatment at temperatures of 350W490°C. The Al alloy ingot processed with the hot working is processed with a cold working of more than 20% after it is treated with a softening treatment as occasion demands, and then the alloy is subjected to cold forging of more than 30% after it is again treated with the softening treatment. After the above mentioned procedure, a solution treatment which is usually made on 2000 series alloys is executed on the Al alloy, so that a homogenized and fine recrystallized structure may be obtained.