View Full Version : Annealing extruded aluminum

04-14-2006, 01:58 PM
Can this be done? I knew you could do this with brass and copper but never heard of it with aluminum. I have pre formed aluminum extrusion that is meant to wrap around the side of a curved surface and it was shipped slightly bent (not a perfect curve). I thought after it was bolted down, since there are hold downs ever 12" or so that it would just even itself out but no go. Someone told me you could actually heat the area with a torch and then quench and hammer it over the radius you need.


04-14-2006, 05:04 PM
This is surmise and opinion, more than solid fact, but my guess is:

A lot depends on which of the gazillion aluminum alloys it happens to be. Saying "aluminum" doesn't really say much when it comes to describing properties.

Regardless of the alloy, I doubt that any aluminum alloy is annealable the way copper is. Copper will get dead-limp soft when annealed, but I don't think you're going to get that kind of behavior with any aluminum alloy.

Beyond that I won't even guess.

Quite likely somebody with more experience than I have may be able to help your out with more solid information.

04-14-2006, 05:32 PM
The few instances I've needed to reshape aluminum I've just heated it "pretty hot" and worked it that way. But your question aroused my curiosity for a more authoritative answer, and I found this:

"Annealing is the term used for softening metal with heat. Non-heat treatable aluminum alloys are annealed by heating to 650 0 F and then simply allowing them to cool gradually. Some stress relief may occur as an added benefit. Heat-treated alloys are annealed by heating to 775 0 F for 2-3 hours and cooling slowly to 500 0 E"

Taken from Tinmantech here: http://www.tinmantech.com/html/repairing_aluminum_article.php

Allan Dimmock
04-14-2006, 05:34 PM
Isn't it just a matter of rubbing on a bit of old fashioned soap and heating the aluminium until the soap turns black ?

04-15-2006, 01:35 PM
I was playing with some 6061 t6 this week, 1" x1/8" thick. Wanting to bend it at 90 degrees. First time i heated it, ended up melting it in half. (Oops!!) Next time I heated it, then bent it, and craked it into two pieces. Not hot enough. Third time, I blackened it with the O/A first (used acetylene by itself), then heated it until the black burnt off. Bent ok this time. No expert by any means, but it worked ok for me. One thing with aluminum is that it transfer heat readily, it's not necesary to have the heat completely even. (Although I did try to heat as evenly as possible with the torch.)