Fatigue crack growth behaviour in ferritic ductile iron with surface crack under reverse bending

In this paper, fatigue crack growth behaviour of ferritic ductile cast iron containing 3.26%C and 4.18%Si was studied. Materials were produced and reverse bending fatigue test specimens were cut from the casting with the thickness of 24 mm. Process annealing heat treatment was applied to the specimens. Semi-elliptical surface cracks were formed and reverse bending fatigue tests were carried out. Fatigue crack growth rates were determined. Stress intensity factors (ΔK) were obtained by Newman–Raju’s equations. Fatigue crack growth material constants (n and c) were determined in Paris–Erdogan’s equation. Fractured surfaces of the specimens were examined by using SEM.