Influence of Environments on Constant Displacement: Stress Corrosion Crack Growth in High Strength Aluminum Alloys

摘要

An experimental investigation was carried out into the applicability of various corrosive environments for stress corrosion crack propagation testing of high strength aluminium alloys using double cantilever beam specimens. Testing under atmospheric conditions was used as a reference. It was found that stress corrosion crack growth under atmospheric conditions was influenced by the wedging action of corrosion products, making the determination of a threshold stress intensity factor less relevant. Corrosion product wedging was particularly important for testing by periodic moistening with a 3.5% NaCl solution. It crack growth promoting effect is advantageous for distinguishing differences between SCC resistant alloys. The crack growth behavior under atmospheric conditions was reflected best by alternate immersion in synthetic seawater. The amount of SCC growth found for continuous immersion in an acidified salt-chromate solution proved to be too small to distinguish between alloys with intermediate and high resistance to SCC.