Sliding and Pitting Wear Resistance of Plasma and Pulse Plasma Nitrided Steel

Abstract

In the present paper, the wear resistance of dc plasma and pulse plasma nitrided AISI 4140 steel has been evaluated under lubricated sliding and pitting wear conditions. Quench hardened specimens were used as a reference. The nitrided specimens were characterised using metallographic, microhardness, residual stress, and surface examination techniques. After surface treatment, lubricated sliding wear tests were performed on a pin on disc machine in which surface treated pins were loaded against hardened ball bearing steel discs. Pitting wear tests were performed on a standard FZG machine. Experimental results indicate that the wear resistance of AISI 4140 steel, especially pitting wear resistance, can be greatly improved by means of plasma and pulse plasma nitriding. However, plasma and pulse plasma nitrided AISI 4140 steel showed very similar sliding and pitting wear resistance.