N.Z. Negm

Formation and properties of a carbonitrided layer in 304 stainless steel using different radio frequency plasma powers

Abstract Radio frequency (rf) inductively coupled plasma was used for carbonitriding the surface of AISI-304 austenitic stainless steel (ASS) samples at different input plasma powers (300–650 W). The morphology and the microstructure of the treated surfaces of carbonitrided austenitic stainless steel samples (CNASS) were examined by optical microscopy (OM) and scanning electron microscopy (SEM). The surface hardness of the treated surfaces as well as the microhardness profile of the samples was measured. X-Ray diffraction was employed to investigate the structure of product phases as a result of carbonitriding process. The results indicate that by using the rf plasma technique, we can greatly improve the tribomechanical properties of these materials. The high rate of carbonitriding (1 μm 2 /s) and the high hardness of CNASS (1375 Hv, 0.1) at plasma input power 550 W have been interpreted in terms of nitrogen and carbon concentration gradients, and microcracks formed in the surface during the plasma process in the compound layer.

RF plasma carbonitriding of AISI 304 austenitic stainless steel

Abstract The rf plasma carbonitriding of AISI-304 austenitic stainless steel was examined as a function of plasma time. The properties of the carbonitrided layer were determined using optical microscopy, scanning electron microscopy, X-ray diffraction and microhardness testing. For the sample treated for 10 min, the rate of carbonitriding was calculated to be ∼0.5 μm 2 /s. The surface hardness of the carbonitrided layer processed for 10 min was 1715 Hv, 0.1 as compared to 228 Hv, 0.1 for the untreated surface. The high rate of carbonitriding and the excellent microhardness of the compound layer have been explained in terms of nitrogen and carbon concentration gradients, microcracks formed in the surface during the plasma process and temperature gradients.

Corrosion Performance and Tribological Properties of Carbonitrided 304 Stainless Steel

In general, the solid solution austenitic phase (γ) with high chromium content (12 % 20 %) is responsible about the excellent corrosion performance of austenitic alloys. This advantage allows these alloys to use in biomedical, food and chemical, pulp and paper chemical, petrochemical, heat exchange and nuclear power plant industries [1-4]. However, most of these applications are suffering from their relatively low hardness and poor tribological properties.