Fatigue crack growth in a coarse-grained iron-silicon alloy

The fatigue crack growth in a coarse-grained Fe-2 wt% Si alloy is investigated in considerable detail. At room temperature, the material is quasi-brittle and the failure mode is mixed cleavage. Under a mode-I cyclic loading, the crack can overcome the barrier effect of grain boundaries, which dominates the overall damage evolution. Associated with the geometrically necessary crack front branching, there are two possible break-through modes for a fatigue crack to propagate across a high-angle grain boundary.