Influence of microstructural and crystallographic inhomogeneity on tensile anisotropy in thick-section Al–Li–Cu–Mg plates

Abstract

Thick-section plates made from a recently developed Al–Cu–Mg–Li alloy have been evaluated to understand the influence of microstructure on the anisotropy of tensile strengths after natural and artificial ageing treatment. Pancake-shaped grains with a coarse substructure and strong crystallographic texture with a β-fibre orientation at the mid-thickness position are observed. In addition, an inhomogeneous distribution of T1 precipitates through the plate thickness has been revealed with the volume fraction of intragranular precipitates ∼40% higher at the plate centre than the ¼ thickness position. Altogether these microstructural features contribute to the in-plane anisotropy of tensile strengths that is ∼5% higher at the mid-thickness position than the ¼ thickness position. The variation of ageing-induced T1 precipitates through the plate thickness further contributes to the through-thickness anisotropy that is ∼3% higher in T8 temper as compared to T3 temper.