Effect of Retained Austenite on Fatigue Strength of Carburized Steel

Abstract

In order to evaluate the effect of retained austenite on the fatigue strength of carburized steels, the rotating bending fatigue tests were carried out by the steel used for marine propulsion gears.
It was found that the fatigue strength has a maximum value at a certain quantity of retained austenite in the specimen with an effective carburized depth. The reason for the presence of this optimum retained austenite quantity is considered on the basis of the residual stress, microstructure and the fracture surface of the carburized surface layer.