The process of spreading nitrogen over the surface of the material to create a hardened surface. These processes are most commonly used on low alloy steels. Ammonia, which is rich in nitrogen, is usually used in the nitriding process. When ammonia comes into contact with the metal at high temperature, it decomposes into Nitrogen and Hydrogen. Nitrogen diffuses to the surface of the material and forms a nitride layer. In this way, the surface and depth of the material up to a certain point reaches a very high degree of hardness compared to the core under the influence of the nitride layer. Nitriding process is generally applied to gears, crankshafts, camshafts, valve parts, die casting parts, forging dies, weapon parts, extrusion and rolling dies, injectors and plastic moulding tools.