On the Sliding Wear Characteristics of Steel Treated by Gas Boronizing

Abstract

This paper deals with the wear characteristics and the mechanism of sliding wear, under unlubricated conditions of boride layers, FeB and Fe₂B formed on S45C steel by gas boronizing.
The results showed that wear characteristic curves of FeB and Fe₂B layers gave similar patterns, and that the wear conditions, under which the maximum wear rates were observed, were 0.30 m/sec in sliding velocity for the FeB specimen and 0.50 m/sec for the Fe₂B specimen. Under these wear conditions, the mechanical wear caused by scratching and oxidative wear coexisted. Under mild wear conditions, oxidative wear preferentially occurred and destruction of the sliding surface was brought about by thermal stress under heavy wear conditions.
From the results of X-ray diffractions, it was found that the wear debris were chiefly composed of iron oxides (α-Fe₂O₃, Fe₃O₄) formed by the oxidative wear and α-Fe and borides (FeB, Fe₂B) scratched by the mechanical wear.