Effect of Graphite Shape and Matrix on Fatigue Strength Characteristic of Cast Iron Using for Engine Component

Abstract

Effect of graphite shape and matrix on fatigue strength characteristic of cast iron was studied. According to result of fatigue test in gray cast irons, effect of difference in matrix on fatigue strength was not significantly observed. Therefore, shape and size of graphite might be more dominant on the fatigue strength. Fatigue strength was well predicted by threshold stress intensity factor range and the maximum graphite size by assuming semi-circular crack in gray and spheroidal cast irons. In case of vermicular cast iron, stress shielding effect due to crack branching should be taken into account to predict the fatigue limit.