A Study on the Damage Behavior of Hybrid 60 and 52100 Steel during Rolling Contact Fatigue

This study investigates and compares the evolution of subsurface hardness and microstructure of Hybrid 60 and 52100 steels under rolling contact fatigue (RCF) testing. Similar microstructural decay was identified for both Hybrid 60 and 52100 steel, evidenced by the formation of elongated ferrite and ferrite microbands during the first stage of the microstructural decay. Nano-sized ferrite grains were also observed in the region with maximum Hertzian stress after 1 × 108 stress cycles for both steels. In addition to the common microstructural decay in the two steels, the 52100 steel experienced microstructural decay in the form of dissolution of residual cementite and tempered carbides. The present study shows that the Hybrid 60 steel develops less microstructural decay than the 52100 steel at the same RCF conditions suggesting that Hybrid 60 could be suitable for replacing 52100 in applications where higher RCF is needed. The improved microstructure stability in Hybrid 60 is attributed to the more stable secondary carbides and intermetallic precipitates as compared to the cementite in the 52100 steel.