7075 aluminum alloy (AA7075) is an aluminum alloy, with zinc as the primary alloying element. It has excellent mechanical properties and exhibits good ductility, high strength, toughness, and good resistance to fatigue. It is more susceptible to embrittlement than many other aluminum alloys because of micro segregation, but has significantly better corrosion resistance than the alloys from the 2000 series. It is one of the most commonly used aluminum alloys for highly stressed structural applications and has been extensively used in aircraft structural parts. 7075 aluminum alloy's composition roughly includes 5.6–6.1% zinc, 2.1–2.5% magnesium, 1.2–1.6% copper, and less than a half percent of silicon, iron, manganese, titanium, chromium, and other metals. It is produced in many tempers, some of which are 7075-0, 7075-T6, 7075-T651.


Un-heat-treated 7075 (7075-0 temper) has a maximum tensile strength of no more than 280 MPa (40,000 psi), and maximum yield strength of no more than 140 MPa (21,000 psi). The material has an elongation (stretch before ultimate failure) of 9–10%. As is the case for all 7075 aluminum alloys, 7075-0 is highly corrosion-resistant combined with generally acceptable strength profile.


T6 temper 7075 has an ultimate tensile strength of 510–540 MPa (74,000–78,000 psi) and yield strength of at least 430–480 MPa (63,000–69,000 psi). It has a failure elongation of 5–11%. The T6 temper is usually achieved by homogenizing the cast 7075 at 450°C for several hours, quenching, and then ageing at 120°C for 24 hours. This yields the peak strength of the 7075 alloys. The strength is derived mainly from finely dispersed eta and eta' precipitates both within grains and along grain boundaries.


T651 temper 7075 has an ultimate tensile strength of 570 MPa (83,000 psi) and yield strength of 500 MPa (73,000 psi). It has a failure elongation of 3–9%. These properties can change depending on the form of material used. The thicker plates may exhibit lower strengths and elongation than the numbers listed above.


T7 temper has an ultimate tensile strength of 505 MPa (73,200 psi) and a yield strength of 435 MPa (63,100 psi). It has a failure elongation of 13%. T7 temper is achieved by overaging (meaning aging past the peak hardness) the material. This is often accomplished by aging at 100–120 °C for several hours and then at 160–180 °C for 24 hours or more. The T7 temper produces a microstructure of mostly eta precipitates. In contrast to the T6 temper, these eta particles are much larger and prefer growth along the grain boundaries. This reduces the susceptibility to stress corrosion cracking. T7 temper is equivalent to T73 temper.


The retrogression and reage (RRA) temper is a multistage heat treatment temper. Starting with a sheet in the T6 temper, it involves over aging past peak hardness (T6 temper) to near the T7 temper. A subsequent reaging at 120 °C for 24 hours returns the hardness and strength to or very nearly to T6 temper levels. RRA treatments can be accomplished with many different procedures. The general guidelines are retrogressing between 180 and 240 °C for 15 min 10 s.

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