Strain-controlled fatigue in B-modified Ti–6Al–4V alloys

The strain-controlled fatigue behaviour of Ti–6Al–4V alloy with up to 0.11 wt.% B addition was investigated. Results show significant softening when the strain amplitudes, ΔεT/2, are ⩾0.75%. B addition was found to improve the fatigue life for ΔεT/2 ⩽ 0.75% as it corresponds to the elastic regime and hence is strength dominated. At ΔεT/2 = 1%, in contrast, the base alloy exhibits higher fatigue life as TiB particle cracking due to strain incompatibility causes easy crack nucleation in the B-modified alloys.