I recently found a few old hatchet, axe blades in the garage of a house I bought 7 years ago. There are not OLD, but a little rusty and no handles. I have enjoyed metal working over the years. More so than woodworking and I need a new Zen hobby. Anyway, I want to try my hand at shaping, engraving and salt water etching with these things. I have seen some examples on youtube that are pretty nice. I took a file to them and they are definitely hardened. What would be the easiest way to anneal these heads so that they are easier to cut/engrave? They will be wall hangers if I am even lucky enough to get one of them there. I have a small outdoor firepit, but I just don`t know if I need forge level heat or what. How do I soften these bad boys up?