Glow Discharge Plasma Nitrocarburizing and Post Oxidation Treatments of SCM 435 Steel

Glow Discharge Plasma Nitrocarburizing and Post Oxidation Treatments of SCM 435 Steel

Plasma nitrocarburizing and post oxidation were performed on SCM435 steel by a pulsed plasma ion nitriding system. Plasma oxidation resulted in the formation of a very thin 1-2 f.l m ferritic oxide layer on top of a 15-25 f.l m E - Fe2-3(N,C) nitrocarburized layer. The growth rate of oxide layer increased with the treatment temperature and time. However, the oxide layer was easily split from the compOlmd layer either for oxidation temperatures above 450'C, or for oxidation time more than 2 hours at oxidation temperature of 400 'C. It was confirmed that the relative amount of Fe203, compared with Fe304, increased rapidly with the oxidation temperature. The amounts of r-Fe₄(N,C) and θ-Fe₃C, generated from dissociation of ε-Fe2-3(N,C) phase during O₂ plasma sputtering, were also increased with the oxidation temperature.