Originally Posted by
Thom Sturgill
A file will break if dropped because it is hardened, but generally not tempered. Tempering takes away some hardness and a file needs all the hardness it can get. My father used to make carving tools from old files, but part of the process was tempering the steel by baking it in the oven. I believe because of the manufacturing method, "crucible steels" like Dougs high vanadium steel and Dave's Cobalt steel require complete heating to finish the sintering process. Also the cryo tempering requires the entire piece be treated. While carbon steel hardens in the 8-900F range, which can be reached with a mapp gas torch, HSS (M2) requires 1450-1500F and is often quenched in molten salt.