7xxx alloys

Description

Aluminium 7xxx alloys include zinc (Zn) and magnesium (Mg) as the major alloying elements. Copper (Cu), manganese (Mn), chromium (Cr) and zirconium (Zr) may be added to the alloys of 7xxx series as minor alloying elements. Aluminum-zinc-magnesium alloys are heat-treatable. Solution treatment followed by either artificial or natural aging allows considerable increasing the yield strength (3-5 times). Ductility of the alloy decreases as a result of the heat treatment. Hardening of the alloys from this group is achieved due to precipitation of the phases MgZn2 and Mg3Zn3Al2t occurring during aging.

7xxx alloys are the strongest of all wrought alloys, boasting strengths exceeding some steels, which is due to using zinc as its primary alloying element. The inclusion of zinc also decreases its workability and machinability, but its exceptional strength justifies these downsides.

7075 aluminum is a commonly used 7xxx alloy for aircraft applications, mobile equipment, and other highly stressed parts, as it is one of the highest strength aluminum alloys available. It has an excellent weight-to-strength ratio and is ideal for highly stressed parts. In the annealed condition, this grade can be formed and heat-treated if necessary. It can also be welded in place or flash (not recommended for arc and gas). 

Applications: 7xxx alloys are widely used in various aircraft structures (forgings, extrusions, sheets) and for manufacturing hydraulic equipment.