Plasma nitriding is one of the techniques used in surface engineering to increase the surface hardness and wear resistance of the austenitic stainless steels. This process, when carried out at low-temperatures (350-400 °C), can increase the corrosion resistance of the produced layer, in relation to the substrate, due to the formation of the "S" phase rich in nitrogen with high resistance to pitting formation. In the present work, samples of AISI 316L austenitic stainless steel were plasma nitrided at temperatures of 400, 450 and 500 °C in a d.c. plasma with a gaseous mixture of 80%H2 - 20%N2. The structures and properties of the nitrided layers were investigated through optical microscopy, microhardness measurements, scanning electron microscopy coupled with EDS, and X-ray diffraction analysis. All of the layers presented an accentuated increase in their hardness, in relation to the hardness of the substrate.
