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.
The purity of aluminum is generally characterized in one of two ways, by terminology or by the Aluminum Association designation system. This article reviews the properties of pure aluminum in purities from 99.99 percent through commercial purity, 99.00 percent. The mechanical properties of aluminum are discussed in terms of tensile properties, stress-strain relationships, and creep. The article also reviews the physical properties of aluminum, such as atomic structure and nuclear properties, atomic spectrum, crystal structure, density, thermal expansion, and thermal conductivity. It discusses the chemical properties of aluminum and presents a summary tabulation of the mechanical strength, ductility, and hardness of pure aluminum.