Influence of Material, Heat Treatment, and Microstructure in Resisting White Etching Crack Damage
SourceIn this study, steels that had undergone different heat treatments resulting in different microstructures were tested under rolling contact fatigue (RCF) and under specific test conditions known to cause white etching cracks (WECs). The test conditions included high slide-to-roll ratios and a lubricant known to promote WECs. It was observed that case-carburized AISI 3310 steel showed longer fatigue life than martensitically through-hardened 52100 steel with respect to a WEC damage mode. To understand how and why the case-carburized steel showed longer life, other material heat-treated combinations were tested and different material strengthening mechanisms were considered. The study examined carburized steel that had been heat treated differently and RCF tested. The 3310 steel was carburized at a lower carbon potential, and post carburize austenitization was done at a lower temperature so that lesser solute quantities would dissolve into the austenite phase prior to the quench step. The carburized steel samples with less solute dissolution showed higher hardness and more compressive stresses than the original carburized steel; however, they showed 75% shorter RCF life than the original carburized steel. These results suggest that solid solution strengthening is the prime contributor to fatigue resistance under WEC damage conditions. In addition, coarse microstructure morphologies obtained through high austenitization temperatures were shown to exhibit poor WEC damage resistance.