Micromechanical response of dual-hardening martensitic bearing steel before and after rolling contact fatigue

Material decay in bearing steels under rolling contact fatigue (RCF) leads to fatigue initiation and failure. This study examines the local structure-property relationship in decayed material through in-situ compression testing of micropillars prepared from a dual-hardening martensitic bearing steel (Hybrid 60) before and after RCF testing. The results demonstrate a pronounced decline in local yield strength (1755–1780 MPa) compared to non-decayed regions (2200–2340 MPa). Discontinuous yield behavior and higher initial stress requirements for dislocation glide are attributed to the presence of ferrite microbands. Crystal plasticity simulations corroborated these findings, confirming a significant increase in critical resolved shear stress (CRSS) and reduced strain hardening in decayed micropillars.