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

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 μm2/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. [Copyright &y& Elsevier]