Stresses higher than anticipated can also accelerate rolling contact fatigue, which is a known precursor to WECs. WECs commence at subsurface during the initial phases of their formation, particularly at non-metallic inclusions. As the sliding contact period extended, these cracks extended from the subsurface region to the contact surface, ultimately leading to flaking. Furthermore, there was an observable rise in the extent of microstructural modifications near the cracks, suggesting that the presence of the crack is a precursor to these alterations.
The direction of sliding on the bearing surface played a significant role in WEC formation. When the traction force opposed the direction of over-rolling (referred to as negative sliding), it consistently led to the development of WECs. Conversely, when the traction force aligned with the over-rolling direction (positive sliding), WECs did not manifest. The magnitude of sliding exerted a dominant influence on WEC formation. Tests conducted at a sliding-to-rolling ratio (SRR) of -30% consistently resulted in the generation of WECs, while no WECs were observed in tests at -5% SRR. Furthermore, the number of WECs appeared to correlate with variations in contact severity, including changes in surface roughness, rolling speed, and lubricant temperature.