Prediction model for fatigue life and limit of steel based on small crack micromechanics

Abstract It is very important to predict fatigue life and limit of steels for material design and they are affected by microstructures. Although a model for the prediction based on microstructural information was proposed, such model doesn’t consider the other important factors, the stress distribution and the crack closure. This study employed the weight function in order to describe the effect of the stress distribution. For the crack closure, a crack closure equation for small fatigue cracks was employed. Also, tension/compression fatigue experiments using three different steels were carried out to validate this model. Predicted fatigue lives and limits showed good agreement with experimental results for all steels. These new extensions expanded the application of this model, e.g. bending conditions.