FOUR FACTORS SHOULD be considered in selecting corrosion tests for aluminum and aluminum alloys. These are: (1) the expected service environment, (2) the type of corrosion expected in service, (3) the primary material requirements of the application which should not be excessively degraded by corrosion, and (4) whether the material requires surface protection for use in the intended environment. Some form of surface protection is almost always necessary for the high-strength 2xxx and 7xxx series alloys.