A new method for prediction of nodular cast iron fatigue limit

This paper is concerned with the ability of the different existing fatigue strength theories to predict the fatigue limit of a nodular cast iron. Different studies exist on the effect of small defects, such as micro-shrinkage cavities or pores and graphite nodules (shape and size), and of microstructure, on the fatigue strength of nodular cast iron. However poor fatigue life predictions are obtained for the nodular cast iron with the existing models. It will be shown on this study that the role of geometrical features such as shape, size, and relative position of either casting defects as well as graphite nodules is an important parameter on the definition of the fatigue limit. A new correlation of fatigue limit with an improved accuracy as compared to existing models is proposed. The new model takes into consideration both intrinsic properties as well as some new geometrical material features.