The 7xxx series of aluminum alloys, which contain zinc, can achieve the highest strengths among all commercial aluminum series, especially when combined with copper and magnesium.
However, these alloys generally have poorer resistance to atmospheric corrosion compared to other aluminum alloys. They are also less tough and more susceptible to stress-corrosion cracking when stressed in the short-transverse direction. Special treatments have been developed to address these issues, which become particularly important when the alloys will be exposed to high short-transverse stresses during use.
Like the 2xxx and 6xxx series, 7xxx alloys naturally age after heat treatment, so it’s crucial to carefully plan and schedule any forming operations to maximize their performance.