Requirements for a Suitable Nitriding Steel

In the early years of nitriding, Adolph Fry at Krupp Steel recognized that certain steels responded better from a metallurgical standpoint in terms of surface hardness, core hardness, distortion, cycle time at temperature, and the formation of stable nitrides. Fry discovered that certain elements respond more readily than others to form stable nitrides during the nitriding process, and this led to the development of the Nitralloy group of steels. Of the alloying elements commonly used in commercial steels, aluminum, chromium, vanadium, tungsten, and molybdenum are beneficial in nitriding because they form nitrides that are stable at nitriding temperatures.