7075 alloy metal aluminum sheet plate is a common alloy in 7000 series aluminum alloy sheet. 7075 aluminum sheet (Al-Zn-Mg-Cu) belongs to super-hard aluminum. As a kind of cold finished wrought alloy, it has great strength and hardness. It’s far better than mild steel. This alloy has good mechanical properties and anode reaction. 7075 aluminum sheet as a typical kind of aerospace aluminum alloy material is usually used for high-end fields.
Zinc is the main alloy element in 7075 aluminum plate. Adding magnesium to the alloy containing 3% – 7.5% zinc can form mgzn2 with significant strengthening effect, which makes the heat treatment effect of the alloy far better than that of aluminum zinc binary alloy.
Increasing the content of zinc and magnesium in 7075 aluminum plate will further improve the tensile strength, but its ability to resist stress corrosion and spalling corrosion will decrease. After heat treatment, it can achieve very high strength characteristics.
7075 aluminum plate is generally made of a small amount of copper, chromium and other alloys. Among them, 7075-T651 aluminum alloy is particularly top-grade. It is known as an excellent product of aluminum alloy, with high strength and far better than any mild steel.
Properties of 7075 aluminum alloy: cold treated forging alloy has high strength, which is much better than mild steel.
Un-heat-treated 7075 （7075-0 temper） has maximum tensile strength no more than 280 MPa （40，000 psi）， and maximum yield strength no more than 140 MPa （21，000 psi）。 The material has an elongation （stretch before ultimate failure） of 9–10%. It is very highly corrosion-resistant and has good strength.
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 aging at 120 °C for 24 hours. This yields the peak strength of the 7075 alloy. 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. Thicker plate 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 micro-structure 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 overaging 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 180–240 °C for 15 min 10 s
7075 super-hard alloy is the most representative one of 7000 series, is usually used as welding or aircraft materials. 7075 aluminum sheet is used for manufacturing of high-strength aircraft structures and other high-stress structural parts with great strength and strong corrosion resistance, such as lower wing panel, stringers, frame of the aircraft.