Atmospheric corrosion characteristics of a commercial rolled zinc alloy containing 1 per cent copper and one unalloyed grade were evaluated after two- and seven-year exposures under the Committee B-3 1957 test program on atmospheric corrosion of nonferrous metals. Comparisons were made with the behavior of three unalloyed grades included in a 20-year Committee B-3 program initiated in 1931. The usefulness of tension tests for determining corrosion rates was explored in both programs.

Weight loss determination appears to be the most reliable means of assessing corrosion rates for zinc. Good agreement among zinc corrosion rates in the two programs was obtained. Zinc composition was found not to significantly influence corrosion rates.

Pitting occurred in the copper bearing alloy most probably as a result of local galvanic action. The pit depth-total penetration ratio decreases as total penetration increases. Tensile properties of zinc were not significantly affected after seven-year exposure. Therefore, pitting is not believed to be of practical importance.

Tension tests are not useful for evaluating corrosion damage in zinc unless a means of compensating for aging effects can be found.