In this study, the fatigue failure behaviors of carburized 12Cr2Ni alloy steel were examined in the long-life regime between 10 4 and 10 8 cycles with about 100 Hz under R = 0. Results showed that this alloy steel exhibited the double S-N characteristics with surface failure and interior failure. From a statistical point of view, the correlation coefficient further proved that the fine granular area (FGA) governed the fatigue performance of carburized 12Cr2Ni alloy steel. Based on the generalized extreme values (GEV) distribution and test data, the predicted maximum defect size was about 23.4 µm. Considering the effect of tensile limit, material hardness, and crack size characteristics, the fatigue strength prediction model under stress ratio of 0 could be established. The predicted fatigue limit for carburized 12Cr2Ni alloy steel at 10 8 cycles under R = 0 was 507.86 MPa, and the prediction error of fatigue limit was within 0.04. Therefore, the results were extremely accurate.

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