I agree, especially if you want to normalise or temper a piece of steel when you really need it to cool as slowly as possible. The old trick is to bury it in broken pieces of brick and heat the whole lot up till the steel is red hot. The bricks let it cool at a sufficiently slow rate to have the desired effect.
I do take on board the point about not making a whole hearth of them though, maby that is not such a bright idea after all.
Um, AIUI you anneal aluminium (and copper ?) by heating it then quenching it. It's steel that you anneal by letting cool slowly.
That's pretty much it, except that quenching aluminum or copper alloys is not required to make it softer, the heat takes care of that. Quenching does limit the time that the metal is exposed to the higher temperatures, though, and thus reduces the oxidation that is faster at elevated temperatures.
Once softened, there are only some of the aluminum alloys that can be hardened by heat treatment while the others, as well as many of the copper alloys, require work hardening to harden up at all.
Cheers Trevor Jones
The point is that you don't need bright orange heat to anneal ally, the temperature of charred household block soap works for me, and therefore a hearth full of SH blocks would maybe be quite a good thing. But OTOH, quite counterproductive if used as a brazing hearth.
Hoo!
Yes, I did eventually realise you meant that :-)
Have something to add? Share your thoughts — no account required.
Ask the community — no account required