7075 aluminum has a unique composition that includes some zinc. As the primary alloying element, it enhances the aluminum’s mechanical properties. That’s why it’s such a popular alloy among aerospace companies, too. It even has improved corrosion resistance over 2000 series aluminum as well.
Stressed Structures and Aerospace Applications
Picking an alloy while designing things for high-stress environments can be difficult. But, high grade 7075 aluminum has become the leading choice for many applications. Even though it’s susceptible to embrittlement, it is ideal for airplanes. Also, it’s seen widespread use in stressed structures, owing to its enhanced stability.
Variable Mechanical Properties
Each alloy in the 7075 series has a unique set of traits. By varying tempering, it’s possible to produce alloys with different mechanical properties. For example, without heat treatment, 7075 only has a tensile strength of 40,000 psi.
However, if you’re using the T6 temper, its tensile strength increases to 75,000 psi. To produce this temper, the metal has to be kept at 450°C for several hours. Following the high-heat treatment phase, an aging phase takes another 24 hours. The alloy is stored at 120°C during this time.
Further enhancement of 7075’s strength is possible by using the T651 temper. If done properly, the final product’s maximum tensile strength can reach up to 83,000 psi. Even its failure elongation has shrunk to 3-9%. That’s significantly lower than the untreated alloy’s failure elongation rate. However, in thicker plates, they have lower strength levels.
