Interactions of plasticity and oxide crack closure mechanisms near the fatigue crack growth threshold

An advanced analytical model developed earlier has been utilized to predict interactions between plasticity and oxide crack closure mechanisms that influence near-threshold fatigue crack growth behavior. Near-threshold closure is complex because multiple closure mechanisms are likely, including plasticity and oxide-induced crack closure. A series of experiments has been performed to validate analytical results. Analytical and experimental results suggest that interactions between plasticity and oxide result in high closure levels near the fatigue crack growth threshold. At sufficiently low ΔK, the combined effects of plasticity and oxide completely closes fatigue cracks resulting in high fatigue crack growth threshold values.