Role of the Cyclic Stability of Retained Austenite in Fatigue Performance of Carburized 14NiCr11 Steel

The role of retained austenite in the fatigue strength of carburized 14NiCr11 steel was studied by considering two gas-carburizing treatments leading to two maximum retained austenite fractions of 20 and 40%. These states led to endurance limit improvements evaluated at 40 and 10%, respectively, compared with the untreated state. These improvements were explained by the evolution of retained austenite during the cyclic loading using the dispersive x-ray diffraction technique. This reveals that the best fatigue strength is attributed to the homogeneous transformation of the retained austenite fraction in the treated layer during the cyclic loading.