The HCF behavior and life variability of a Ti-6Al-4V alloy with transverse texture

In this study, the microtexture effect on HCF behavior of a hot-rolled Ti-64 plate was investigated. The fatigue life scatter was relatively small and the life variability exhibited a single distribution mode due to microstructural and textural effects. All samples exhibited the Stroth-type crack initiation and the number of pile-up locations between the initiation facet and surrounding propagation facets was related to the life variability. Cracks tended to initiate at the boundary of two microtextured regions (MTRs) located in sample surface area and this is likely caused by the preferred dislocation pile-up between “hard” and “soft” α grains at MTR boundary. During early facet propagation period, crack front was deflected when crossing MTR boundaries. There was no crack front deflection when striation propagation mode became dominant in the high ΔK regime. The closely orientated grains within MTRs provided an easy path for microcracks to propagate and caused the overall deterioration of fatigue properties.