I made a knife of sorts once. It was no protean hero Rambo forging with finnish maids reciting the Kalevala ! I found a railroad spike and managed to heat and bang it into a semblence of a knife and then file a "edge" of sorts. The spike head made for a nice hammer and I split a billet of wood. I later learned the spikes are indeed made into knives. They have a high manganese content and seem to actually "work harden" under the stress of passing trains.