Aluminium Guide · Lesson 03

Aluminium alloys: what 6063, 6061 or 7075 mean

The alloy number tells you what was added to the aluminium. Profiles almost always use the 6000 series, and each alloy has its place.

5 minutes’ read

In short

The first digit shows the main alloying element: the 6000 series contains magnesium and silicon.
6063 is the joinery alloy, used for windows and doors: it extrudes easily and anodises very well (215 MPa in T6).
For structures, 6061 and 6082 are used (260 and 290 MPa); 7075 is the strongest, but only in simple shapes.

How to read the numbers

Alloys for extrusion and rolling are identified by four digits. The first digit tells you the main alloying element:

Series	Main element	Typical use
1000	Almost pure aluminium (99% or more)	Electrical conductors, sheet, packaging
2000	Copper	Aerospace, machined parts
3000	Manganese	Roofing sheet, utensils
5000	Magnesium	Marine, structural sheet
6000	Magnesium and silicon	Extruded profiles: windows and doors, structures
7000	Zinc	High-strength parts

The 6000 series dominates extrusion because it has good strength, flows well through the die and can be heat-treated: it hardens in the ageing oven.

The most common alloys for profiles

Alloy	Minimum strength in T6	What it is used for
6060	190 MPa	Windows and doors, decorative profiles, frames, enclosures and complex profiles with thin walls.
6063	215 MPa	The aluminium joinery alloy: windows, doors, façades, railings, furniture and architectural profiles.
6005A	270 MPa	Lightweight structures, tubes and hollow profiles for demanding uses, rails, vehicle bodies, transport and ladders.
6061	260 MPa	Structural and machined parts, marine, bicycles, brackets, flanges and machine components.
6082	290 MPa	The strongest of the 6000 series: structures, bridges, cranes, scaffolding, trailers and highly stressed parts.
7075	540 MPa	Aerospace, moulds, highly stressed mechanical parts and sports equipment. It is extruded as bars and simple profiles.

Minimum tensile strength according to EN 755-2 for profiles with small wall thicknesses. It varies with the thickness and the type of profile.

How to choose

If the finish matters (windows and doors, furniture, shopfronts): 6063 or 6060.
If it is a lightweight structure with hollow profiles: 6005A.
If it will carry loads or be machined: 6061 or 6082.
If you need maximum strength and the part will not be welded: 7075.

More strength is not always better: harder alloys extrude more slowly, do not allow such thin walls and give a poorer anodised finish.

Frequently asked questions

What is the difference between 6063 and 6061 aluminium?

6063 extrudes more easily and anodises better: it is the alloy for windows and doors (215 MPa in T6). 6061 is stronger (260 MPa) and machines better, which is why it is used for structural parts.

Which aluminium alloy is used for windows?

6063 and 6060, in T5 or T6 temper.