Graded Hardness Design in the Surface Modified Steels by Plasma Nitriding

Plasma nitriding behavior of various Fe-Cr alloys has been studied in order to investigate surface design for improving mechanical properties of the steels. It was observed that microstructure and properties of nitrided layer strongly depends on the chromium content and process parameters. In the case of plasma nitrided low chromium content alloys the hardness decreased gradually from the surface toward the nitriding front, in contrast with plasma nitrided high chromium content alloys which the hardness kept constant through the nitirided layer. However, controlling nitriding parameters properly, resulted in graded hardness profile of nitrided phase, even in the case of high chromium content alloys. A frictional wear examination results on plasma nitrided Fe-Cr steels, showed that graded hardness nitrided layer should be a good candidate for improving wear resistance and other mechanical properties of the steels.