Fatigue crack propagation in β Ti–15Mo–5Zr–3Al alloy

This paper describes the fatigue crack propagation (FCP) for five materials having different microstructures of β Ti–15Mo–5Zr–3Al alloy. With one exception, the microstructure was found to have very little or no influence on FCP behavior. The one exception was the material having the largest β grain size, which showed higher FCP resistance than all other materials due to higher crack closure levels. The effects of stress ratio on the FCP behavior could not be realized solely in terms of the crack closure mechanisms, because static fracture mechanisms operated during FCP depending on the magnitude of the maximum stress intensity factor, Kmax. Furthermore, it was found that the FCP resistance of all the materials was considerably lower than that of α/β Ti–6Al–4V alloy, which was primarily attributed to lower crack closure levels of the β alloy.