Active Screen Hydrogen Free Plasma Nitriding Steel

The paper presents the results of experiments on strengthening the flat surface of cylindrical samples (AISI 5140 steel) by hydrogen-free nitriding in a glow discharge plasma with an active screen. Two nitriding regimes were compared in which the samples were either under the cathode or floating potentials. Nitriding was carried out at 550°C for 3 hours. A homogeneous hardened layer with a thickness of ~150 μm was formed over the entire surface of the samples treated under a floating potential. On the surface of samples under the cathode potential, hardening is observed only in the form of a cylindrical edging at a distance of no more than ~ 2 mm from the sample edge.