Radiofrequency cold plasma nitrided carbon steel: Microstructural and micromechanical characterizations

► C38 carbon steel samples were plasma nitrided using a radiofrequency (rf) nitrogen plasma discharge. ► RF plasma treatment enables nitriding for non-heated substrates. ► The morphological and chemical analyses show the formation of a uniform thickness on the surface of the nitrided C38 steel. ► Nitrogen plasma active species diffuse into the samples and lead to the formation of FexN. ► The increase in microhardness values for nitrided samples with plasma processing time is interpreted by the formation of a thicker nitrided layer on the steel surface.