EN AW 7075 and EN AW 6082 represent two different strength steps in aluminium. The choice usually comes down to a single question: will the part be welded?
Zinc against silicon
6082 is based on the aluminium–magnesium–silicon system: silicon 0.70–1.30%, magnesium 0.60–1.20%, manganese 0.40–1.00%. That system gives moderate strength but is weldable — part of the strength can be recovered by heat treatment after welding.
7075 is an aluminium–zinc–magnesium system: zinc 5.10–6.10%, magnesium 2.10–2.90%, copper 1.20–2.00%. That composition gives one of the highest strengths attainable in aluminium; according to our datasheets its yield strength is 410 MPa and its tensile strength 510 MPa. In 6082 those are 270 and 330 MPa.
The price is welding. 7075 hot cracks in fusion welding and the weld zone loses its strength permanently; in practice it is considered non-weldable. Joining is done with rivets, bolts or adhesive.
The second difference is corrosion: the copper in 7075 lowers its corrosion resistance and brings susceptibility to stress corrosion cracking. 6082 is markedly more durable in that respect and takes anodising well.
Comparison in numbers
| PROPERTY | EN AW 7075 | EN AW 6082 |
|---|---|---|
| Zinc (Zn) | 5.10 – 6.10% | max 0.20% |
| Magnesium (Mg) | 2.10 – 2.90% | 0.60 – 1.20% |
| Copper (Cu) | 1.20 – 2.00% | max 0.10% |
| Silicon (Si) | max 0.40% | 0.70 – 1.30% |
| Manganese (Mn) | max 0.30% | 0.40 – 1.00% |
| Chromium (Cr) | 0.18 – 0.28% | max 0.25% |
| Tensile strength | 510 MPa | 330 MPa |
| Yield strength | 410 MPa | 270 MPa |
| Shear strength | 300 MPa | — |
| Elongation | 8% | 16% |
| Density | 2.81 g/cm³ | 2.71 g/cm³ |
| Modulus of elasticity | 72 GPa | 71 GPa |
| Thermal conductivity | 155 W/m·K | 170 W/m·K |
| Electrical conductivity | 33% IACS | 44% IACS |
| Weldability | Not welded in practice | Good |
| AMS | 4078 · 4124 | — |
Values are taken from our product datasheets; section thickness and the applied heat treatment regime change the result.
Which one, and when?
EN AW 7075 is required — aircraft and defence industry structural parts, machined (milled) highly loaded components, mould plates, racing and aerospace fasteners. If the part is to be machined from solid and strength is critical, 7075 is the right side.
EN AW 6082 is required — welded structures, bridge and platform members, truck and trailer chassis, crane booms, structures working outdoors. Where there is welding, 7075 cannot be used.
Neighbouring grades
For a copper-based medium-strength alternative, see our EN AW 7075 – 2017A comparison; for marine environments and welded structures, our EN AW 5083 – 5754 article.
Technical datasheets
EN AW 7075 — chemical composition, mechanical values, standard equivalents
EN AW 6082 — chemical composition, mechanical values, standard equivalents
Both grades are supplied to order in round bar, flat bar, plate, sheet, pipe and forged forms. Contact us for a quotation.