A study of the wear performance of duplex treated commercial low-alloy steel against alumina and WC balls

Abstract

The objective of this work is to study the improvement of the tribological properties of low alloy steel using a duplex treatment of low pressure carburizing and the deposition of a Cr–(WC–Co) coating by dual RF magnetron sputtering. The treatments result in a 500μm thick carburized layer and a sputtered coating thickness of ~2μm. Tribological tests were made with a ball-on-disk tribometer under dry conditions with low load and low speed. The worn surfaces of the disk, the wear counterpart, and resulting debris were analyzed by X-ray diffraction, optical microscopy, optical profilometry, and a scanning electron microscope equipped with an energy-dispersive X-ray spectrometer. The wear performance of the samples was evaluated in terms of wear rates and friction coefficients during the sliding processes against two different counterparts. Experimental results have shown that sliding wear, of the investigated duplex treated low alloy steels, is strongly dependent on the counterface materials. Under testing conditions, the overall wear performance of a Cr–WC coating (Cr/W ratio of 1.12:1) deposited onto the surface of a carburized low alloy steel (0.61wt.% C; HV=654±5) can be recommended as the best. The duplex-treated samples suffered severe, concentrated wear when against alumina. This wear is characterized by a combination of delamination, mild abrasion and oxidative wear. However, the wear mechanism seems to be oxidative and adhesive when against WC balls.