Stress-Corrosion Cracking of Aluminum Alloys^[1]

In high-strength aluminum alloys, stress-corrosion cracking (SCC) is known to occur in ordinary atmospheres and aqueous environments. This article discusses the mechanisms of SCC in aluminum alloys, providing information on two main types of SCC models: those of anodic dissolution based on electrochemical theory and those that involve the stress-sorption theory of mechanical fracture. It reviews three different categories of experiments used to compare SCC performance of candidate materials for service. The categories are tests on statically loaded smooth samples, tests on statically loaded precracked samples, and tests using slowly straining samples. The article describes SCC susceptibility and ratings of SCC resistance for high-strength wrought aluminum products, such as 2xxx, 5xxx, and 7xxx series alloys, aluminum-lithium alloys, and 7xxx alloys containing copper.