If you’re planning to fabricate your tank or bodywork from aluminium (“aluminum” for my North American friends ?) you’ll most likely need to “anneal” the sheet of metal.
This video will show you how to do it.
The aluminium sheet I buy locally is a 5005 alloy (aluminium mixed with other elements) and it comes supplied in a “H34” temper – which is a type of heat treatment of the metal, and to be precise it is “Strain-hardened and stabilized – 1/2 hard”.
While it is supplied “1/2 hard”, I can make it “fully soft” and much easier to work with. We have to change the structure of the metal and we do this with heat, which is called “annealing”.
Annealing is simply the process of heating the metal up to a point where the microstructure of the metal changes – effectively eliminating the temper it was supplied with – then letting the metal cool in the air.
Depending on the sheet metal you have available in your local area, annealing may not be necessary. I have seen other metalshapers in the USA suggest purchasing aluminium alloys in the 3000-3003 range as they are much softer. That is fine for the USA, but here in Australia I simply don’t have that choice. I have to use what I can find.
In the case of aluminium, it is relatively easy to perform annealing with an oxygen/acetylene torch. And after you have been hammering on aluminium for a while, it tends to “work harden” and you can repeat the annealing process again to soften the metal. Then keep hammering, then soften again. You can repeat this a number of times until you have achieved the shape you want.