Types of 7075-T6 Aluminium and how to choose between them
7075-T6 Aluminium is a high strength aluminium alloy with zinc as the main addition, in the T6 temper. It is used for aerospace and motorsport parts where strength to weight is the deciding factor. This entry explains what it is, what the numbers on a data sheet mean, and what to put on a drawing.
It is written from the point of view of the buyer and the drawing office: the values that are realistic in production, the ones that cost money, and the way the result is verified. Where an industry sets the requirement, automotive is used as the example: a fixed takt, because a late delivery stops the line.
The main types
7075-T6 Aluminium is not one thing. The variants below differ in what they suit, and the choice is usually made on the part rather than on preference.
- Plate – suited to aerospace fittings.
- Bar – suited to bicycle and motorsport components.
- Forging – suited to mould plates.
- Extrusion – suited to structural brackets.
How to choose
Start from the feature that has to work, then from the quantity. A automotive run suits one arrangement, a repeat run suits another, and the wrong choice shows up as cost rather than as failure.
The second question is what has to be measured. Where AS9100 with material traceability applies, the inspection requirement usually decides the route before the machine does.
Comparison at a glance
| Parameter | Value |
|---|---|
| Tensile strength | 572 MPa |
| Yield strength | 503 MPa |
| Hardness | 150 HB |
| Density | 2.81 g/cm³ |
| Machinability | good, chips break well |
| Corrosion resistance | lower than 6xxx, usually clad or anodised |
Applications
7075-T6 Aluminium is used for aerospace and motorsport parts where strength to weight is the deciding factor, and in practice it appears most often in aerospace fittings, bicycle and motorsport components, mould plates, structural brackets.
How it fits into a machining route
7075-T6 Aluminium is chosen at the drawing stage, and everything downstream follows from it: the tool geometry, the cutting data, the heat treatment and the certificate. Changing the grade later is a different part, not a different quote.The route is fixed before the first part is cut, and it is the route rather than the individual setting that holds the result: material cost is several times that of 6061. Where a drawing calls for something the route cannot hold economically, that is raised at quotation rather than after the parts are made.
Standards, documentation and what is issued
The documentation requirement is AS9100 with material traceability. Material is supplied against a certificate where the application calls for it, inspection results are recorded with the job, and the records are kept so that a repeat order can be compared with the first instead of being measured from scratch.
Standard dimensional inspection with a certificate check is the verification step. Where a customer format or a standard report is required, it is agreed before the batch starts, because a report written after the event is a report nobody can use.
Frequently asked questions
What tolerance should be specified for 7075-T6 Aluminium?
±0.01 mm is realistic in production. Tightening it beyond the functional requirement increases cost without improving the part.
Which material is usually used?
7075-T6 aluminium is the usual choice, supplied against AS9100 with material traceability.
How is the result verified?
Standard dimensional inspection with a certificate check, with the results recorded so a repeat order can be compared with the first.
What is the most common mistake?
Leaving it bare in a corrosive environment, because it pits.
How long does it take and what does it cost?
A realistic cycle is fast, but with more tool wear than 6061, and the cost driver is material cost is several times that of 6061.
Related capability
If you are specifying 7075-T6 Aluminium on a drawing and want a second opinion on the route, send the model and the quantity. The first response is a manufacturability review with the likely risk points and a quotation, so the decision can be made on facts rather than on a price alone.
Machining, inspection and documentation are handled in one place, which is why the dimensional report and the material certificate arrive with the parts rather than after them.
Related entries
These entries sit next to 7075-T6 Aluminium in the encyclopedia: Inconel 718, C3604 Brass, Splined Shafts. Reading them together gives a fuller picture of how the process, the material and the measurement affect each other.
