I am trying to fix up some body sheet metal that got pretty banged up a long time ago, after which somebody bashed it into more or less the right shape and put tons of lead over it. I’ve removed the lead and started trying to smooth the metal with hammer and dolly and a stud welder, but it has gotten so many creases and dents that it’s gotten hardened like spring steel, and seems to simple refuse to change shape. (This is a fairly high-crown area in the roof, right above the doors, and there are braces and stuff behind it that make it hard to get access from inside.)
Is there any way that I can anneal the metal or otherwise make it easier to work? What would happen if I just heated the whole area red-hot with a torch and let it cool slowly?