In many cases tool-steel is still more closely designated according to the smelting processes from which it has resulted, such as ingot-steel, weld-steel or according to the method of production, such as Bessemer steel, Martin steel, crucible steel, puddled steel, shear steel, etc.; further accord ing to certain peculiarities, such as natural or self-hardened steel, hard-centred steel, soft-centred or mild-centred steel, tungsten-steel, chrome-steel, nickel-steel, etc; and finally, according to the purposes to which it is to be applied, such as knife-steel, scythe-steel, magnet-steel, punch-steel, chisel steel, etc.