Hobbies And Interests
Things You'll Need
Instructions
Light the torch or forge. Small pieces, such as knives, can be heat-treated with a torch. For larger objects a forge is more effective due to the limited amount of oxygen present.
Heat the metal evenly by constantly moving the white tip of the torch's flame over the surface. Monitor the temperature with a laser pyrometer: when the steel reaches at least 1333° F it is ready. Alternatively, hold a magnet to the steel. When the magnet is no longer attracted to the metal, it has transformed from ferrite to austenite, which means it is ready to be rapidly cooled and hardened. Hold the piece of metal only with long-handled tongs whenever you need to manipulate or move it. In the case of using a forge, measure the temperature in the same fashion, with either a laser pyrometer or the magnet technique. Using a forge will heat the metal far more evenly and uniformly as well as to prevent oxygen from drawing out carbon atoms.
Quickly and evenly, submerge the piece of steel completely in a bucket filled with peanut oil. Ensure you have enough oil to allow the piece of metal to be completely submerged. The oil should be at room temperature and the metal left in it until cool. Peanut oil has a very high flash point, lessening the risk of fire, but you should use long-handled tongs and keep a fire extinguisher handy just in case. Once cooled, the metal will be extremely hard.
Set the oven to 325° F. Place the piece of steel into the oven directly on the rack and let it temper for about 15 minutes. Turn off the oven and allow the metal to cool naturally. It should now have a yellow, straw-like color to it, and will be the appropriate hardness to keep an edge.