Aluminummagnesium

Aluminum–magnesium alloys, or Al–Mg alloys, are aluminum-based materials in which magnesium is the primary alloying element. The best-known subgroup is the 5xxx-series (for example 5052, 5083, and 5086), valued for light weight, good corrosion resistance, and strong weldability. Magnesium contents in these alloys typically range from about 2 to 5 percent by weight; small additions of manganese and sometimes chromium or zirconium improve strength, grain structure, and corrosion resistance. In many 5xxx alloys the strength is primarily increased by cold working rather than heat treatment; some related alloys that include silicon or other elements may be heat-treatable.

Properties depend on composition and processing but generally include high ductility, good toughness, and excellent corrosion resistance, including in seawater. The density is low, contributing to high strength-to-weight ratios. Fabrication options include casting, hot or cold rolling and extruding; welding is usually straightforward, making Al–Mg alloys popular for fabricated structures. They are commonly used in marine applications, pressure vessels, transportation components, and consumer and industrial equipment.

Limitations include reduced strength at elevated temperatures and, in some environments, sensitivity to certain types of corrosion such as pitting in chloride-rich media. Although alloying and processing have advanced, Al–Mg alloys are typically outperformed at high temperatures by other aluminum families such as Al–Mg–Si and Al–Zn–Mg–Cu when very high strength is required. Recycling is straightforward and widely practiced.