Mechanical study of crystalline orientation distribution in Ti-6Al-4V: An assessment of micro-texture induced load partitioning

Abstract

Microtextured regions are known to have a detrimental effect on the fatigue performance of near α and α/β titanium alloys. Due to the elastic anisotropy of α titanium, stress heterogeneities are expected to result from such microstructural features. The present work is an assessment of their influence on the elastic stress field, using Fast Fourier Transform-based computations on a 2D extruded aggregate built from a real microstructure. The contribution of the microtextured regions was then isolated by comparing simulations obtained on a synthetic aggregate with similar grain morphology and texture but removed microtextured regions through a redistribution of crystalline orientations. The analysis of the computed fields revealed that the average stress experienced by α grains is only weakly affected by the neighborhood and mostly determined by the elastic anisotropy of α titanium. Nevertheless, complex mechanical interactions between microtextured regions were evidenced. Indeed, load partitioning and non-local influence on the stress field were found to result from the presence of microtextured regions. The implications on fatigue crack initiation are discussed in light of these results.