Nitriding is used to enrich the surface layer of ferrous materials with nitrogen or - in the case of nitrocarburising - with nitrogen or carbon. This enhances not only the hardness, but also the wear resistance, fatigue strength, and corrosion resistance. Also the antifriction properties are improved. Moreover, there is no transformation of austenite to martensite, so the workpiece retains its geometry to a large extent.
This process generally achieves hardness depths of up to 0.8 mm. Following a development by Dr.-Ing. Helmut Reese ("Profundieren"), nitriding hardness depths in excess of 1.0 mm are now possible on certain materials. With its low distortion properties, nitriding can be used in many cases instead of case or surface hardening - provided that suitable steels are used. Nitriding steels are listed in DIN 17211 and EN 10085.