GlossaryKind of term: Manufacturing termEN AW-7075
What is EN AW-7075?
EN AW-7075 is a high-strength aluminium alloy with zinc, magnesium and copper, used where strength at low weight matters; fusion welding is not recommended.
EN AW-7075 (AlZn5.5MgCu, material number 3.4365) is a heat-treatable 7000-series wrought alloy with zinc, magnesium and copper. In T6 or T651 it is among the strongest aluminium alloys sold as standard plate and bar. It is used for aerospace parts, mould and die parts, robotics and sports components, and thin-walled precision parts. It machines well, with short chips. Fusion welding is not recommended, and its corrosion resistance is lower than that of 6082.
What does the standard say about EN AW-7075?
Composition and chemical designation are in EN 573-3, tempers in EN 515, and properties per product form and thickness in the product standards, such as EN 485-2 for plate. T651 is solution heat treated, stretched and artificially aged. T7351 is overaged after stretching: lower strength, but much better resistance to stress corrosion cracking. Aerospace parts often follow their own specifications, with requirements for temper, testing and certification; the drawing or the order then names which.
How does EN AW-7075 behave in the shop?
The harder material usually leaves less burr and a cleaner wall than 6082. It is not stiffer: the elastic modulus is nearly the same, so a thin wall deflects about as far under the same cutting force. Thick plate can move when a lot of material comes off, even in T651. It can be anodised and hard anodised, but the colour is less even and the layer behaves differently from one on 6082; for a cosmetic part, agree the finish with the anodiser in advance. If the drawing leaves the choice between 7075 and 6082 open, agree it with the designer; besides strength, price per kilo, availability and any welding or anodising requirement come into it.
What is EN AW-7075 often confused with?
7075 is not 7020, a weldable alloy of lower strength used in welded structures. T651 and T7351 are not interchangeable either: a drawing that specifies T7351 has chosen resistance to stress corrosion deliberately, and T651 is no substitute.
Frequently asked questions
When should I use 7075 instead of 6082?
When strength at low weight matters and the part does not need welding, for example in aerospace, moulds or thin-walled precision parts. For frames, plates and housings 6082 is often enough, and it welds and anodises better.
Can 7075 aluminium be welded?
Fusion welding is not recommended: the alloy is prone to hot cracking and loses strength beside the weld. If a 7000-series part has to be welded, 7020 is the usual choice. 7075 parts are normally joined with bolts, rivets or adhesive.
Is 7075 stiffer than 6082?
No. Both have almost the same elastic modulus. 7075 is stronger, so it yields later, but under the same load a wall deflects just as far. For chatter in thin-walled milling, switching to 7075 helps little.