Can I make my chassis out of Aluminium?

Frequently Asked Questions about The Edge Buggies answered here!

Can I make my chassis out of Aluminium?

Postby Baboon » Sat Apr 26, 2008 1:33 pm

All Edge chassis & parts are made out of Mild Steel for ease of manufacture & to keep the costs reasonably cheap.

Yes it’s possible to make a buggy chassis from Aluminium.

But Aluminium has characteristics that make it much more difficult to work with compared to mild Steel.

Welding a heat treated alloy anneals the heat affected area.
So the strength of the welded area becomes the same as that material in annealed condition.
This means the welded area becomes softer than the rest of the bar work.

Unless you heat treat the whole chassis it’s going to be very weak.

Without heat treating the chassis welds & the surrounding area will be soft & prone to failure.
To beef up the structure to combat this lack of strength will add weight.

There are very few Aluminium alloys that are suitable for the welding task.
The high tensile 7000 series alloys are not suited to welding.
This is the reason that many of the early aluminium tubbed race cars were riveted.
By riveting sheet aluminium you can then use the tensile grades of this alloy.
Only the 6000 series Aluminiums are weldable, 6061 being the most suitable.
Ultimate tensile strength around 45ksi, but falls off to 24ksi when welded, heat treating will bring it back up to 45ksi.

As a guide aluminium would have to be 1.44 the thickness of steel to achieve the same bending stiffness.
But the aluminium would only be .48 of the weight even though its thicker.
So there is a good weight advantage.

When welding aluminium allot of effort has to be put into creating a stiffer joint.
Gusseting corners, extra bracing to create more stiffness.
Aluminium does not tolerate flexing at weld joints, it cracks.
This is because Aluminium fatigues very quickly.
You can flex steel all day long & it will withstand this stress.
Aluminium will fatigue & fail with only 1/3rd the amount of cycles compared to steel.
So there needs to be extra wall thickness in the tube as well as care not to have undercuts at the weld.

Corrosion is another factor.
When an object is pushed close to its mechanical limit it only takes the slightest amount of corrosion to bring it to the point of failure.

Aluminium needs to be protected from the elements as it corrodes quickly.

When all said & done you need to be skilled in the art of Aluminium fabrication.
You need to understand its advantages & disadvantages to be successful in achieving a good strong structure.
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