Annealing aluminum

[mrollings53]

I've got a sheet of 6061-T6 I got for free from work. I plan on using it to make a fan shroud, only problem is I can't bend it as is. Anyone have any pointers on annealing it. I've read of rubbing soap on the sheet or covering it in soot from an acetylene torch and then heating it until the soap turns black or the soot burns off. Also of wiping oil on it and then heating until the oil burns off. I'm just not certain on which process will guarantee results and how long I will have to work with the metal. Of course I could always build a kiln and do it the proper way. Thanks for the tips.

[hazelnut]

Never tryed to myself with aluminum but i did see how it was done on one of these bike building shows. Guy showed a piece of sheet aluminum and it was stiff and wouldnt bend at all for him a he was going to make a gas tank out of it. So he layed it on the bench and heated it up with a mapp gas torch and just let it sit and slow cool on its own. They showed him picking it up after it cooled and it was flexable, He beat and banged it into 1/2 of a fuel tank and when he was finished with it and wanted to make it hard again he heated it up again and poured water on it to cool it. He picked it up and started pushing and pulling on it to show that it was stiff again for the camera. Ive did it to steel doing body work and dont see why it wouldnt work on aluminum.

[champdog]

look on you tube. tons of how too's and I saw a bunch on Annealing aluminum. Champdog

[flyboy71]

Soap method works, so does a shaprie marker heating till it disappears. Be aware of the grain direction too on that alloy especially since its not a good one for bending. Any sharp bends in line with the grain will crack sooner than bends perpendicular to the grain.

[mrollings53]

Thanks for the info flyboy. Do you think a propane torch (the big ones not the little bottle ones) would do, or should I use an acetylene torch? How long do I have before the metal ages back to T6?

[flyboy71]

A propane torch might work but my experience has been using acetylene minus the oxygen. Just watch the marker till it disappears and keep the torch moving. If youre doing a large area youll need a lot of heat, if youre bending in one spot you only need to mark and heat down the bend line. Let the piece cool gradually. As far as age hardening Im not quite sure. Just the act of annealing and then bending or shaping will work harden it some. If youre talking a fan shroud this isnt as big of a deal as it would be if its structural.

[mrollings53]

I'm not worried about structural integrity. I need to know if I anneal it in the evening will I have enough time, before it hardens back, to shape it the next day. Now I just need to find an acetylene torch.