Effect of lattice defects on tribological behavior for low friction coefficient under lubricant in nanostructured steels

Abstract

The effect of lattice defects on the tribological behavior for low friction coefficient under lubricant was investigated in the nanostructured steels produced by heavy plastic deformation processes. In the surface-nanostructured SUJ2 bearing steel, the stable tribological behavior with low friction coefficient was observed in the ball-on-disk tests under PAO (Poly-α-Olefin 17) - oil or ester - oil, in comparison with the non-deformed steel. This phenomenon was enhanced by using the lubricant with polarity (ester - oil). In addition, the similar phenomenon was observed in the ULC (ultra-low carbon) steel with high-density of lattice defects (grain boundary, dislocation and so on). This reason seems that the molecules of lubricant interacted strongly with the nanostructured surface due to the deviation of electrons (polarization) at the region with high-density of lattice defects.