Simple Heat Treating for a High Carbon Steel Knife Blade – Part 2, by Steve A.
(Continued from Part 1. This concludes the article.) The blacksmith would heat the steel to a bright cherry red, check it with a magnet, bank the forge fire over the steel, and let it cool in the dying fire overnight, ensuring a very slow cooling rate. A modern heat treat shop would heat the steel to temperature in an atmosphere-controlled furnace and then turn the furnace off until the steel has cooled sufficiently. Another way to do this starts by clamping the file by its tang upright in a metal vise and annealing it with a torch. If you slowly …