Cyclic softening behavior of Ti-6Al-4V alloy at macro and micro-scale

The cyclic softening behavior of Ti-6Al-4V alloy with three typical microstructures at room temperature has been studied through cyclic deformation experiments at macro-scale and cyclic nanoindentation experiments at micro-scale. Strain control cyclic deformation tests were conducted on specimens with equiaxed, duplex and Widmannstatten microstructure, respectively. Displacement control nanoindentation tests were conducted on the specimen with duplex microstructure. Results show that equiaxed microstructure shows distinct softening since the first cycle, while, duplex and Widmannstatten microstructures exhibit hardening phenomenon at the initial several cycles and then exhibit cyclic softening in subsequent cycles. Cyclic nanoindentation results indicate that both primary and lamellar α phase exhibit cyclic softening phenomenon at micro-scale and the amplitudes of softening vary with grain orientations.