Comparison of the fatigue and fracture of Ti–6Al–2Zr–1Mo–1V with lamellar and bimodal microstructures

The present study compares the high cycle fatigue (HCF) properties of the Ti–6Al–2Zr–1Mo–1V alloy with lamellar and bimodal microstructure. This comparison study includes the high cycle fatigue (resistance against crack initiation) with different ratio of stress (R = 0.1 and −1) and different notch concentration factor (Kt = 1 and 3), and the fatigue crack propagation behavior. The comparison principally showed much lower high cycle fatigue strength for bimodal microstructure as compared with lamellar microstructure for smooth and notched specimens at positive load ratio. Whereas, the difference of the high cycle fatigue strength result at negative load ratio is small for the two microstructures. The results of fatigue crack propagation test show that the lamellae structure also provides higher crack growth resistance than the bimodal structure, and the lamellar microstructure displayed a more tortuous and deflected crack path.