Effects of microstructure on fatigue crack growth behavior of Ti–6Al–2Zr–1Mo–1V ELI alloy

In this paper, fatigue crack growth behavior of Ti–6Al–2Zr–1Mo–1V ELI alloy with differences in the lamellar structure was investigated at room temperature. Heat treatments were performed in order to produce the microstructures that vary in α lamella width and colony size. Results show that, with adequate mechanical properties, the microstructure formed through air cooling from the β-phase field presents better fatigue crack propagation behavior than microstructures formed by other heat treatment paths. The fatigue crack growth proceeds along the planes either perpendicular or parallel to the long axis of α lamellae. The explanation for this behavior is related to prismatic slip along the a1 [21¯1¯0] and a2 [112¯0]/a3 [1¯21¯0] directions.