Damage behavior and microstructure evolution of ER8C wheel steel under rolling wear conditions

In this study, the damage behavior and microstructure evolution of ER8C wheel steels at strip-quenched martensite white-etched areas (WEA) of a rail steel surface were studied based on rolling wear experiments. The results showed that with an increase in the number of rolling cycles, the wear rate appeared stable even though the friction coefficient decreased continuously. The surface wear mechanism of friction with a rail steel substrate area (S-CA) and that of friction with martensite white-etched area (WEA-CA) changed from oxidation wear and adhesion wear to oxidation wear and fatigue wear. The proeutectoid ferrite and pearlite in both areas underwent severe plastic deformation in the surface layer, resulting in the ferrite being elongated and refined into fibers and the cementites in the pearlite being fractured and partially dissolved. The surface hardness increased, and the depth of the hardened layer also increased. Fatigue cracks propagated mainly along the deformed proeutectoid ferrite and pearlite interface after surface formation. Under the same wear parameters, the plastic deformation degree and hardening degree of the WEA-CA were considerably higher than those of S-CA, indicating that the martensite WEA on the rail surface accelerated the wear of the wheel. Therefore, an increase in the slip ratio (0.5%–1%) promoted the wear and microstructure evolution process. • The S-CA and strip WEA-CA wear mechanisms are different. • The crack propagation mechanism is studied. • The surface microstructure refinement is serious and the hardness is the highest. • Strip WEA-CA damage, microstructure refinement and hardness are greater than S-CA.