Effects of surface roughness and alloying element on surface morphology and tribology of low-alloy steel after gas-nitrocarburizing

Abstract

This paper aimed to study the effects of initial surface preparation and Chromium (Cr) content on morphology and tribological properties of gas nitrocarburized AISI 1015 steel and AISI 4115 steel. Two different surface preparation methods, i.e., polishing and machining, were employed in order to achieve different surface roughnesses and topologies. Surface treatment was performed using nitrocaburizing technique. After the surface treatment, white layers formed by gas nitrocarburizing were observed and analyzed by following techniques; surface roughness test, optical microscopy, scanning electron microscopy, X-ray diffraction, microhardness test, and pin-on-disk test. It was found that morphology and tribological properties of the nitrocaburized steels were significantly influenced by the initial surface roughness. The results indicate that the wear volume loss increases with an increase in the initial surface roughness, whereas increasing of Cr element increases the surface hardness of steel, but decreases the wear resistance.

Keywords

• gas nitrocarburizing
• surface roughness
• low alloy steel
• wear