Aluminum Company of America

Bruce A Halter

Dhruba J Chakrabarti

Robert W Westerlund

A method is disclosed for treating an aluminum alloy product in order to impart a fine grain structure and thereby improve formability and surface finish characteristics. According to this method, the product is first heated to a first temperature high enough to dissolve soluble constituent phase particles into solid solution. The product is maintained at this first temperature long enough to dissolve a major portion of the soluble constituent phase particles. Thereafter, the product is subjected to a controlled cooling process. The product is first cooled from the first temperature, at a first rate that is rapid enough to minimize the precipitation of coarse-grained constituent phase particles, to a second temperature that is below the temperature at which such coarse-grained constituent phase particles will precipitate out. Then, the product is cooled from the second temperature, at a second rate that is within a range of about 1-300 degrees F. per hour, to a third temperature that is at least 50 degrees F. below the second temperature. After the temperature of the product has been reduced to the third temperature, the product is cold worked. After cold working, the temperature of the product is raised to a fourth temperature sufficient to cause recrystallization of the product. The product so treated will exhibit improved formability and surface characteristics, and may exhibit an average grain size of less than about 30 microns.

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Bettendorf, IA, United States of America

Bruce A Halter