Dry sliding wear behaviour of plasma nitrocarburised AISI 304 stainless steel using response surface methodology

Abstract

This paper deals with preparation of plasma nitrocarburised layers on austenitic stainless steel sample and subsequent assessment of its wear resistance. Plasma nitrocarburising was carried out on AISI 304 stainless steel samples at temperatures 400–450 and 560°C for 6 h using pulsed glow discharge plasma in a gas mixture of 78%H2, 20%N2 and 2%C2H2. Characterisation of the coating was carried out through hardness survey, XRD and optical microscopy. The sliding wear behaviour was studied using conventional pin-on-disc equipment. Experiments were designed using response surface methodology. The wear rate was studied as a function of applied load and sliding velocity to obtain empirical model. Worn surfaces were analysed using SEM. The wear mechanism of plasma nitrocarburised surface is found to be mild and dominated by oxidation and microabrasion, while in the uncoated, it is characterised by strong adhesion and severe plastic deformation.