Gas Nitriding and Nitrocarburizing
Gas nitriding is based on the decomposition of ammonia (NH3) at temperatures between 500 and 600°C (930 and 1110°F) according to:
NH3 = Nsoluted + 3/2H2
The nitriding potential (KN), which is connected with the formation of different phases in the surface layer and therefore acts as one of the key factors to control the process, can be derived from the reaction as:
KN = pNH3/pH23/2
The graph shows the Lehrer diagram for the formation of four iron phases in ammonia-hydrogen mixtures.
Volume 4D, Heat Treating of Irons and Steels -> Tool Steels -> Introduction to Heat Treating of Tool Steels -> Heat Treatment Applied to Tool Steels
