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

TL;DR

This study investigates how microstructural and crystallographic inhomogeneities in thick Al-Li-Cu-Mg plates influence tensile anisotropy, revealing microstructure-driven variations in strength across the plate thickness.

Contribution

It provides new insights into the microstructural factors affecting tensile anisotropy in thick-section Al-Li alloys, highlighting the role of grain structure and precipitate distribution.

Findings

Inhomogeneous T1 precipitate distribution affects tensile strength.

Mid-thickness position exhibits ~5% higher in-plane anisotropy.

T8 temper shows ~3% higher through-thickness anisotropy than T3.

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 beta-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 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 1/4 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.