RF plasma carbonitriding of AISI 304 austenitic stainless steel

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 μm2/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.