Microstructure-Fatigue Relationships for Cast Irons

A microstructural fatigue crack nucleation model is developed for cast irons with graphite inclusions of different shapes, based on Eshelby’s solution for ellipsoidal inclusions and the Tanaka-Mura-Wu model for fatigue crack nucleation. This model is used to analyze ductile cast iron with nodular graphite microstructure, gray cast iron with flake-like graphite microstructure, and compacted graphite iron with vermicular graphite microstructure. Excellent agreements are found between the model predictions and the experimental data or the Coffin-Manson-Basquin best-fit correlations. This has established an analytical microstructure-fatigue prediction approach, which saves the time and cost of fatigue design with regards to these materials.