A Mechanistic Approach to Understand Rolling Contact Fatigue (RCF) Induced Microstructural Alterations

Rolling bearing elements under rolling contact fatigue (RCF) exhibit subsurface microstructural alterations e.g. dark etching regions (DERs) and white etching bands (WEBs). The formation mechanism for such microstructural alterations is debatable and requires further understanding. Current research work presents a systematic approach where bearing balls of standard AISI-52100 steel are tempered at 400°C for 240 mins and then subjected to RCF test in a rotary tribometer at 5 GPa contact stress, 160°C till 37M cycles. Another virgin sample was RCF tested and subjected to a similar heat treatment. Subsurface microscopic analysis for pre and post tempered RCF tested samples have revealed that the formation of these microstructural alterations is a combined effect of dislocation assisted carbon flux along with thermally activated carbon diffusion. Additional tests have been carried out to conduct the parametric study with variations in operating temperature, cyclic frequency, and applied load.