the effect of interaction between hardness, inclusion and microstructures on the fatigue behavior of steel

in this study, the fatigue behavior of alloy steels with different hardness values was tested. results showed that the fatigue limit increases by the increment of hardness up to 400 vickers whereas it drops when the hardness value exceeds 400 vickers. fractographic observations using scanning electron microscopy revealed non-metallic inclusions as the dominant fatigue crack initiation sites. by predicting the threshold stress intensity, with the aid of scanning electron microscope observations of the fracture surface and comparing the fatigue limit of the steels, the appropriate effect of hardness on the fatigue behavior of the steel can be presented. finally, simple and accurate models were proposed for the estimation of the fatigue limit by means of hardness.