Abstract

It is well known that plasma nitriding improves the mechanical, tribological, and corrosion-resistance properties of low-alloy steels. Nitride formation on the surface of the material could be the cause of these changes. However, there is no information specifically regarding the analysis and quantification of microstructural parameters produced after a nitriding plasma treatment on AISI 4140 steel. This work aims to determine the microstructural parameters (crystallite size and microstrain) and to quantify the nitride phases formed on the surface of the alloy by the nitriding treatment in order to find a possible correlation with the values of microhardness. The microstructural parameters and phase quantification were calculated from a Rietveld analysis using Materials Analysis Using Diffraction (MAUD) software. The results indicate that characteristics, such as phase, composition and thickness, can be easily changed by varying the working parameters. The obtained microhardness value increases with the presence of a gamma '-Fe4N phase. Correlations between the microhardness, and corresponding microstructural parameters and phase quantification of the nitrided surface are discussed.