ohiomoto wrote on 01/29/18 at 04:05:18:What's your annealing method? Do you use soap, marker, thermometer or anything to gauge temperature? This is something I've been interested in.
For 5052 I use a mapp gas torch for heat and a tempilstik that has a 650f melt. You blast the area you want to anneal holding the torch in one hand and the tempilstik in the other. Occasionally withdraw the torch and swipe with the stik, when it reaches temp the stik will will leave a heavy melted trace of wax.
Alternatively premark the area you want to anneal with scribble of a permanent marker and proceed with heating. The marker fades to almost nothing at you reach annealing temp. I think this is akin to the old method of flaming with an acetylene torch to leave a black soot on the surface. The organic smudge that the torch or marker leaves will essentially evaporate around that 650 F.
Either way the sound when you tap it with anything hard changes substantially once it's annealed, it will go from a ting ting to a much lower pitch when annealed. They say it only takes an instant at 650 F, quenching rate is of no consequence and the melt temp of 5052 aluminum is about 1100 F so it's a pretty easy process anneal without melting.
This process works for 5052 but won't work for 6061 with any kind of temper. The heat treat on 6061 is far more involved to anneal. I think it will also work on any aly alloy that only work hardens but google your alloy to be sure.
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