EFFECT OF PLASMA NITRIDING TEMPERATURES ON CHARACTERISTICS OF AISI 201 AUSTENITIC STAINLESS STEEL

Abstract

Samples of AISI 201 austenitic stainless steel were produced by plasma nitriding at 350[Formula: see text]C, 390[Formula: see text]C, 420[Formula: see text]C, 450[Formula: see text]C and 480[Formula: see text]C for 5[Formula: see text]h. Systematic characterization of the nitrided layer was carried out in terms of micrograph observations, phase identification, chemical composition depth profiling, surface microhardness measurements and electrochemical corrosion tests. The results show that the surface hardness and the layer thickness increased with increasing temperature. XRD indicated that a single S-phase layer was formed during low temperature ([Formula: see text][Formula: see text]420[Formula: see text]C), while Cr2N or CrN phase was formed besides S-phase when nitrided at 450[Formula: see text]C and 480[Formula: see text]C. The specimen treated at 390[Formula: see text]C presents a much enhanced corrosion resistance compared to the untreated substrate. The corrosion resistance deteriorated for samples treated above 450[Formula: see text]C due to the formation of chromium nitrides.