Aluminium, General

Is Extruded Aluminium Pure Aluminium?

Extruded Aluminium

Choosing the right metal for your project is important for making sure it’s strong, durable, and safe. But with so many options available, it can be tricky to know which one is best.

One option you might be looking at is extruded aluminium. This is a type of aluminium made by pushing aluminium through a die to create specific shapes – kind of like squeezing toothpaste out of a tube, where the shape of the opening determines how it comes out.

Before you decide, it’s a good idea to know exactly what extruded aluminium is made of and why it matters – like whether it’s pure aluminium or mixed with other metals. This can help you figure out if it has the right qualities for your project.

MG Metals has been supplying custom aluminium extrusions in all shapes and sizes for over 20 years, so we know a thing or two about it. Keep reading to find out everything you need to know about aluminium purity and why it’s important!

How Pure Is the Aluminium Used in Extrusions?

Typically, extruded aluminium isn’t made from pure aluminium, but from aluminium alloys. These alloys mix aluminium with other metals like copper, magnesium, or zinc to make it stronger, harder, and more resistant to corrosion, making it more useful for a wider range of applications.

Pure aluminium is softer and not as durable than alloyed aluminium, so it’s not ideal for most structural or industrial uses. However, it’s still great for things like electrical wiring or heat sinks, where its excellent electrical and thermal conductivity really shine.

Why Is Extruded Aluminium Usually Made of Alloyed Aluminium?

Extruded aluminium is usually made from alloyed aluminium rather than pure aluminium for several key reasons:

1. Improved Strength and Hardness

Pure aluminium is relatively soft and has low tensile strength, which makes it much less useful in structural applications. When alloyed with elements like magnesium, silicon, copper, or zinc, it becomes much stronger, harder, and more resistant to wear. This makes alloyed aluminium a better choice for load-bearing and structural components.

2. Higher Corrosion Resistance

All aluminium forms a protective layer that helps prevent corrosion, but when you mix in elements like magnesium, silicon, or zinc, it becomes even more resistant. This makes it especially well-suited for things like saltwater environments or industrial settings. Different aluminium alloys offer varying levels of protection, depending on what they’re needed for.

3. Better Extrudability

Alloying can improve the extrudability of aluminium, allowing it to flow more smoothly and consistently during the extrusion process. Alloys like the widely used 6000 series, which contain magnesium and silicon, strike a great balance between easy extrusion and strong mechanical properties. This makes them ideal for producing complex shapes and thin walls without compromising the material’s strength.

4. Improved Machinability

Many aluminium alloys are easier to machine and shape compared to pure aluminium, which is softer and more likely to cause galling (metal buildup on cutting tools). This improved machinability results in cleaner, more precise surfaces that need less post-processing to achieve a smooth finish.

5. Thermal and Electrical Conductivity Balance

Pure aluminium has excellent electrical and thermal conductivity, but many applications need a better balance between conductivity and strength. Alloyed aluminium sacrifices a bit of conductivity but gains the extra strength needed for more demanding applications (e.g. heat sinks, structural elements in electronics) in its stead.

6. Heat Treatability

Heat treatment improves the mechanical properties of metals by altering their internal structure through methods such as quenching, ageing, or tempering. This works thanks to alloying elements like magnesium, silicon, copper, and zinc, which form precipitates in the aluminium to boost its strength and hardness.

If you try to heat-treat pure aluminium, it won’t change much since it doesn’t have the right alloying elements. It will remain soft and won’t gain the extra strength and durability seen in heat-treated alloys.

7. Improved Surface Finish

Alloyed aluminium responds better to surface treatments like anodising or coating. Elements like silicon and magnesium in the alloy help create more consistent and uniform oxide layers, resulting in a smoother and more durable finish. In contrast, pure aluminium forms a weaker oxide layer, making it more prone to wear and damage.

8. Cost Efficiency

In many cases, alloyed aluminium is a more cost-effective option because it allows manufacturers to use less material or thinner sections while still maintaining the required strength and performance. Since pure aluminium is softer and weaker, it would need more material to achieve the same strength, making it a less economical choice.

As you can see from the points above, alloyed aluminium is the go-to choice for most extrusions for good reason – it offers the perfect blend of strength, corrosion resistance, formability, and cost-effectiveness that many industries need. Pure aluminium, while offering excellent corrosion resistance and conductivity, simply doesn’t have the mechanical robustness needed for structural uses, which is why alloyed aluminium dominates in extrusion processes. 

Premium Aluminium Extrusions, Cut to Your Exact Needs

Now that you’ve got a good grasp of aluminium extrusions, you might be thinking about sourcing the perfect ones for your project. The great news? You won’t have to search far.

As the UK’s top supplier of custom-cut aluminium extrusions, MG Metals is here to provide exactly what you need. We’ve got a wide range of sections ready for you to choose from, including:

All our extrusions come in different grades, sizes, and thicknesses and can be cut to your exact measurements for a perfect fit. We also offer finishing options like anodising and powder coating, so you can start using them right away!

Ready to give your project the materials it needs to succeed? Get a free quote online or give us a call on 01794 521070 today!