Aluminum 7075

Zinc-alloyed and, at 570 MPa in T6, as strong as many steels while weighing a third as much — this is the alloy that made all-metal aircraft practical. The price is that it cannot be fusion welded without cracking, it is more prone to stress-corrosion cracking than 6061, and it costs several times as much. Choose it only when the part is bolted or riveted and the strength is genuinely needed; otherwise 6061 is the better engineering answer.

Properties

Density

2,810 kg/m³ — 2.81 g/cm³

Melting range

477–635 °C

Tensile strength

220–570 MPa

Young's modulus

71.7 GPa

Thermal conductivity

130 W/(m·K)

Thermal expansion

23.6 µm/(m·K)

Floats in water

No

Magnetic

No

What it is used for

• Aircraft wing spars and fuselage frames
• Competition bicycle and motorsport parts
• Rifle receivers and rock climbing hardware
• High-load machined fixtures

How it compares

Does it rust?

No — aluminium cannot rust, because rust is specifically iron oxide and there is no iron in it. It does oxidise, immediately and constantly, but aluminium oxide is hard, tightly bonded and only a few nanometres thick, and it protects the metal beneath rather than flaking away. It does corrode galvanically when in contact with a dissimilar metal in a damp environment, which is a different mechanism.

Is it magnetic?

Aluminum 7075 is not ferromagnetic. It is often assumed to be because it is a metal, but most metals are not — only iron, nickel, cobalt and a few alloys are attracted to an ordinary magnet.