2. Preliminary heat treatments

2.1 Quenching and tempering

With the exception of nitriding on austenitic stainless steels and nitrocarburizing on unalloyed carbon steels, the state of heat treatment of the material to be nitrided is particularly important and, in many cases, decisive for the quality of the final product. In general, most steels are used in the quenched and tempered condition, and we have already pointed out that in this case it is necessary for the final tempering to have been carried out at a higher temperature than the nitriding temperature, so that the characteristics of the base metal do not change. As treatment times can be very long, it is important to ensure that the temperature/tempering parameters for nitriding and tempering before nitriding are matched. Generally speaking, an annealing...