Formation of a wear-protective glaze layer on GCr15 bearing steel under dry sliding at room temperature

Abstract

The formation of a protective glaze layer during sliding in high-temperature environments usually enhances the wear resistance of metallic materials. However, GCr15 bearing steels typically operate at temperatures below 160 °C, making it difficult to form a glaze layer within this temperature range. In this work, surface mechanical rolling treatment (SMRT) is used to produce a ∼750 μm-thick gradient nanostructured (GNS) surface layer on GCr15 bearing steel. The friction and wear properties of the SMRT samples were investigated to explore if a wear-protective glaze layer can be formed during dry sliding at room temperature. Analyses on the surface morphologies and compositions revealed that the glaze layers were successfully generated on the worn surface for the SMRT samples, mostly related to abundant oxides generated on the worn surface as a result of fast grain boundary diffusivities and high nucleation rates in the nano-grained surface layer. The formation of a protective glaze layer consists of Fe₂O₃ and SiC results in the significant decreases in the coefficients of friction and wear volumes by inhibiting the occurrence of severe adhesion. After sliding for 9000 cycles, the wear volume of the SMRT samples was reduced by ∼53.2 % relative to that of as-received (AR) samples at a load of 110 N. In comparison, adhesion induced Si-rich amorphous phases on the worn surface might hinder the diffusion of oxygen and suppress the formation of glaze layer on the AR samples under dry sliding.