Exploratory Development of High Strength, Stress-Corrosion Resistant Aluminum Alloy for Use in Thick Section Applications

An alloy has been developed which exhibits a good resistance to stress-corrosion cracking at 25 ksi or higher stress in the short-transverse direction based on 30 days exposure in the 3.5% NaCl alternate immersion test. Estimated minimum strength of three-inch thick plate exceeds the guaranteed minimum strength of the closest competing aluminum alloy by 3 ksi and the advantage increases with increasing thickness. Eccentricities in the results of 84 day alternate immersion tests and lack of data regarding performance of alloys of this type in natural environments for longer than 10 months, however, indicate that caution must be used in extrapolating the results of the accelerated tests to predict service performance.