The rate of dissolution of a 99.99 percent pure, one way cold rolled aluminum sheet as received was determined in 1 N hydrofluoric acid, and compared with the rates obtained with a 400 to 575 C recrystallized aluminum specimen of the same quality. No significant differences in rates could be detected. There also was no difference in the dissolution rates of surfaces cut under different angles with respect to the direction of cold rolling.
The same dissolution behavior was observed with 99.998 percent pure aluminum in 0.5 N barium hydroxide solutions; there was no difference in rates of the cold rolled and recrystallized samples, except for cold hammered samples, which showed higher rates. Differential heat treatment of aluminum alloys (with 1 and 2 percent copper), however, produced different rates; the samples heat treated at 200 C exhibited lower rates of dissolution.
The conclusion reached is that cold work itself evidently does not influence the rates of dissolution of aluminum in hydrofluoric acid and in barium hydroxide solutions. However, the effect of cold work may be felt indirectly by creation of cracks and fissures in the metal, which increase the rate of dissolution. Changes in the constitution of the aluminum due to the heat treatment if the metal is impure, may also influence the rates of dissolution.
