Patent ID: 8002913

Claim:
A method of manufacturing a wrought aluminum alloy product of an AA7000-series alloy, the method consisting of the steps of: a. casting stock of an ingot of an AA7000-series aluminum alloy having 0.15 to 0.35% Si, and at least 0.9% Cu; b. preheating and/or homogenizing the cast stock at a temperature of less than 500° C.; c. heat treating the cast stock at a temperature in a range of more than 500° C. but lower than the solidus temperature of the subject aluminium alloy; d. hot working the stock by rolling; e. optionally cold working the hot worked stock; f. first solution heat treating (SHT) of the hot worked and optionally cold worked stock; g. second solution heat treating of the worked stock at a higher temperature than the first SHT, the temperature being in a range of more than 500° C. but lower than the solidus temperature of the subject aluminium alloy; h. cooling the SHT stock; i. stretching or compressing the cooled SHT stock or otherwise cold working the cooled SHT stock to relieve stresses; j. ageing the cooled and stretched or compressed or otherwise cold worked SHT stock to achieve a desired temper, and wherein heat treatments c and g are carried out at a temperature in a range of more than 500° C. but lower than the solidus temperature of the subject aluminum alloy to dissolve constituent phase Mg 2 Si, and wherein this heat treatment step c is carried out after the homogenisation heat treatment prior to hot working.