Study of the wear behavior of ion nitrided steels with different vanadium contents

Powder metallurgy tool steels are technologically well established, being employed in several applications. However, for certain situations, as in the case of components submitted to severe wear, it is necessary to enhance its surface properties. Among the surface hardening techniques, ion nitriding has proven to be a good candidate for treating powder metallurgy tool steels, since the parts are less susceptible to distortions, as can occur on other conventional surface treatments. The objective of this work was the verification of the effect of vanadium on ion nitriding and, consequently, on wear behavior. The alloys with different vanadium contents were ion nitrided at 550 °C for 1, 3, and 5 h. The nitrided layers were characterized by microhardness test, optical microscopy (OM), scanning electron microscopy (SEM) with energy-dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), and pin-on-disk test. The hardness values of the layers enhanced significantly after ion nitriding treatment, due to the formation of VN. The wear test revealed that hardness enhancement resulted in a lesser mass loss for a compound layer of VN and γ′-Fe4N. The treatment time did not influence the shape and size of carbides present in these steels.