Effect of cathodic cage size on plasma nitriding of AISI 304 steel

• Studied the influence of cathodic cage size on active screen plasma nitriding.
• High surface hardness for smaller cathodic cage size.
• Phase transformation from γN to Fe2–3N, Fe4N at 400 °C, 4 h; without CrN.
• Enhanced corrosion resistance for smaller cathodic cage size.

The aim of this work is to investigate the influence of cathodic cage size on active screen plasma nitriding of AISI 304 stainless steels. The specimens are nitrided in fixed processing conditions while using CC with diameters of 13, 15, 17, 19 and 21 cm. The surface morphology, compound layer thickness and elemental composition, phase composition, hardness profile and corrosion resistance of the processed specimens is assessed. The results show that when the CC diameter is reduced, surface hardness profile and corrosion resistance significantly improve, while iron nitrides (Fe2−3N,Fe4N)(Fe2−3N,Fe4N) are formed along with the expanded austenite phase (γN)(γN).