Why do these four alloys come up so often?
The 6xxx series are aluminium alloys with magnesium and silicon as the main additions. Together the two elements form Mg2Si, a phase that hardens the metal during heat treatment. The family extrudes well, resists corrosion, welds and accepts surface treatment, which is why most extruded profile is made from it. European standards write the designation as EN AW-6060; this article uses the short form. What follows describes general tendencies. For exact limits go to EN 573-3 for composition and EN 755-2 for mechanical properties.
How do the four compare?
| Characteristic | 6060 | 6063 | 6005A | 6082 |
|---|---|---|---|---|
| Extrudability | Very high | Very high | Medium | Low |
| Strength level | Medium | Medium | High | Highest |
| Surface appearance | Very good | Very good | Good | Fair to good |
| Quench sensitivity | Low | Low | Medium | High |
| Typical use | Architectural, decorative, heat sinks | Windows, facades | Structural frames, ladders | Structural, machinery, transport |
The table gives direction, not a ranking. Real behaviour depends on section geometry, wall thickness and process conditions.
What does extrudability mean in practice?
Extrudability describes how fast a section can be pressed, at what load and with what surface quality. The more hardening elements an alloy contains, the more it resists flow even when hot. The press needs more force, exit speed drops and the die wears faster, and all of that shows up in cost per metre. Strength and extrudability therefore tend to pull in opposite directions.
When are 6060 and 6063 the right answer?
These two are the workhorses of the industry. Their low flow stress lets thin-walled, multi-leg and hollow sections run at high speed, and their surface takes paint and other finishes well. Both can usually be cooled with forced air and then aged, which keeps production simple. Strength is medium: minimum yield strength depends on the alloy, temper and wall thickness, so use the applicable EN 755-2 table. Window and facade profiles, lighting housings, heat sinks and frames are typical examples.
Where does 6005A fit?
6005A gives more strength than 6060 and 6063 and presses more easily than 6082. It is a sensible compromise for load-bearing sections with moderate wall thickness: ladders and scaffolding, rail and road vehicle structures, machine frames. Its quench sensitivity is higher than that of 6063, so thick sections may need faster cooling than air provides. 6005A is a distinct alloy from 6005, so specify the full designation in an order.
When is 6082 chosen?
6082 is the strongest of the four. Its manganese content raises strength and also makes pressing harder: higher press load, faster die wear, lower exit speed and difficulty with thin, complex shapes. To reach full strength it usually needs a fast water quench at the press. It is chosen where strength comes first and the section suits the process: structural members, cranes, machinery and vehicle components.
How do corrosion resistance and welding differ?
None of the four contains much copper, so all show good corrosion resistance in indoor and outdoor service, and the differences between them are small. All weld well. The heat of welding, however, softens the heat-affected zone and removes part of the strength gained by heat treatment. For a welded load path, design with the reduced strength in mind and keep welds away from the most highly stressed areas where possible.
Which questions help decide?
- How much load must the part carry? Required yield and tensile strength narrow the field.
- How complex is the section? Thin walls, narrow gaps and hollows favour 6060 and 6063.
- What finish is needed? For coated or visible surfaces, surface quality matters from the start.
- Will it be welded? Account for the softened zone.
- Which temper? Strength depends on temper as much as on alloy. See the guide to tempers T4, T5, T6 and T66.
What mistakes are common?
- Asking for maximum strength everywhere. A stronger alloy than needed raises die and press cost and can compromise the surface.
- Leaving out the temper. T4 and T6 of the same alloy behave very differently.
- Treating the finish as a later step. For coated or visible parts the surface expectation is part of the alloy decision.
- Reading standard values as typical values. Standards give minimum values. Measured values are usually higher, but design should rest on the minimum.
How do alloy and section interact?
Section geometry can limit the alloy. A thin, balanced section runs easily in almost any of these alloys, while a thick, lopsided one may be impractical in a strong alloy. Decide alloy and section together; the rules for the section are in designing profiles for extrusion, and the overall route is described in the step-by-step process summary.
Which alloy suits an order is settled against your drawing and requirements and confirmed in writing in the quotation. Send the drawing and annual volume through the quote request page.
Frequently asked questions
What is the main difference between 6060 and 6063?
Both are Al-Mg-Si alloys that suit thin walls and complex sections. 6063 has a slightly wider composition window and somewhat higher minimum strength in some tempers, but for many applications the two are interchangeable.
Which alloy should I use for a structural part?
Load-bearing parts are usually drawn from 6005A or 6082. If the section is complex, 6005A is often the more practical choice because it presses more easily.
Why is 6082 harder to extrude?
Manganese and other additions raise strength but also raise flow stress, which increases press load and die wear. The alloy also generally needs faster cooling at the press to reach its strength.
Is the alloy choice enough on its own?
No. The same alloy gives different strength in different tempers, so alloy and temper should be specified together.
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