Assessment of surface and subsurface evolution under rolling contact fatigue of a pearlitic steel

The assessment of surface and subsurface evolution of rolling/sliding elements manufactured of pearlitic rail steel is investigated using a rolling contact fatigue (RCF) test. The experiments are carried out under different contact pressures in boundary lubricated condition, with 0 % and 2 % slide-to-roll ratios (SRR). The micro-pit area on the contact surface was greater for 2 % SRR than for 0 % SRR. As the load cycles continue, these micro-pits are going to become macro-pits. Under higher load and more SRR, these macro-pits link to form surface-initiated spalls in subsequent RCF tests. The anisotropic surface was destroyed with applied SRR conditions in each RCF test, as the distribution of power spectral density (PSD) became nearly uniform in each direction after the RCF test. The rolling element's subsurface shows the breaking and bending of pearlite. Plastic shakedown and ratcheting response are accountable for deforming subsurface, and as a result, subsurface hardness increases. Subsurface fatigue cracks are visible from MnS inclusion. Changes in surface topography characteristics are also investigated since they impact surface fatigue.