1. In the process of two-stage nitriding a layer with a dense zone of e carbonitrides is formed, which ensures dimensional stability of machine parts and good operating characteristics. Grinding can be replaced with light polishing. 2. The properties are best for the nitrided case with a thin (several μm) dense layer of e carbonitrides. The presence of a dense layer accelerates internal nitriding despite the low nitrogen potential of the atmosphere in the second stage of nitriding. 3. To obtain a nitrided layer of smaller thickness (parts of machines not subjected to overhaul) one can use brief gas nitriding with a given nitrogen potential for each steel.