How macrozone size and morphology influence yield in titanium alloys investigated using fast Fourier transform-based crystal plasticity simulations

Abstract

Titanium alloys exhibit complex microstructures containing heterogeneities at different lengthscales. Although the size of primary α grains is typically in the micrometer range, processing of α/β titanium alloys can introduce millimeter long clusters of α particles with the same or nearly the same crystallographic orientation. These microtextured regions (MTRs), also called macrozones, are known to have a detrimental influence on the alloy performance under cyclic loadings. Recent studies evidenced an effect of the degree of microtexture on the yield strength of polycrystalline aggregates. In the present work, numerical simulations of the macroscopic response of large 3D aggregates containing MTRs with different shapes and sizes were performed using a fast Fourier transforms-based crystal plasticity model. Both macroscale response and microscale stress and strain fields were found affected by the presence of MTRs and their features. A mechanistic understanding of the relation between the mechanical behavior at different scales is discussed to obtain insights into the, still poorly understood, effect of microtextured regions on tensile properties.