Material Response to Rolling Contact Loading

Abstract

The material response to rolling contact loading has been analyzed using quantitative X-ray diffraction methods. This has led to the discovery of preferred crystalline orientation in very narrow subsurface regions of endurance-tested 6309 deep groove ball bearing inner rings. The high hydrostatic pressure field, derived from the load-induced three-dimensional stress field in each Hertzian contact load cycle, allows substantial microplastic deformation to be accommodated in the subsurface layers. This microplastic deformation is accompanied by transformation of retained austenite, decay of martensite and the development of texture and residual stresses, one of which is a subsurface tensile stress in a direction normal to the surface. Both the preferred orientation and the tensile residual stress allow for crack propagation parallel to the rolling contact surface. Based on these findings, an outline of a qualitative model for rolling contact fatigue is presented.

The evolution of hardness and tribofilm growth during running-in of case carburized steel under boundary lubrication

“…The indentation loads of 50-gf and 500-gf used in this study corresponded to depths of 1.4 μm and 4.8 μm respectively, which exceed the range of tribofilm thickness (50 -200 nm) seen in literature [62,82]. Another reason the tribofilm may have had little effect on the observed hardness gains was because of its relative difference in hardness compared to the base material.…”

Strain-induced martensite decay in bearing steels under rolling contact fatigue: Modelling and atomic-scale characterisation

“…However, this process can be reactivated if a dislocation-assisted carbon flux is present. It is believed that the microstructural alterations in bearing steels occur at the plastic shakedown stage of RCF where a steady state plastic flow is present [25]. According to the analysis in Ref.…”

Observations and Location of Acoustic Emissions for a Naturally Degrading Rolling Element Thrust Bearing

“…The L10 is defined as the number of hours in service that 90% of a group of bearings subjected to the same conditions (load, speed, and lubrication) will survive before the onset of fatigue. It should be noted that the theoretical estimation of rolling contact fatigue is known to be subject to variability or scatter when compared to experimental results and this has been attributed to the probability of inclusions in the steel material located in the highest load zones of the race [12]. It is also worth noting that the actual test period leading to visual damage on the race was much faster than the theoretical calculations.…”