A fatigue assessment approach involving small crack growth modelling for structural alloy steels with interior fracture behavior.

Highlights • The rougher morphology of FGA reveals the rather distorted crack growth path. • A fatigue strength evaluation model is developed. • The predicted crack growth rate reflects the discontinuous crack growth behavior. • An assessment method is proposed for predicting allowable fatigue strength. Abstract A fatigue assessment approach for interior inclusion-FGA (fine granular area)-fisheye induced fracture was proposed through experimental investigation of very high cycle fatigue properties of two high-strength low-alloy steels. The rougher morphology of FGA reveals the rather distorted crack growth path and slow crack growth rate. A strength evaluation model related to defect size and fatigue life was developed, using which the predicted results are in agreement with the experimental results. Based on the modelling of micro-crack growth rate, the evaluated value can be less than the magnitude of one Burger's vector, which reflects the discontinuous crack growth behavior within FGA. [ABSTRACT FROM AUTHOR]