Effect of Natural Ageing on Strength and Anisotropy in Aluminium Alloy AA 6005C

Abstract

During processing of age-hardenable AA 6xxx series alloys for automotive applications the sheets may experience significant time spans between solution heat treatment at the aluminium supplier and age hardening upon the final paint bake cycle at the carmaker. Natural ageing during these pause times is known to greatly affect materials properties of autobody sheet. In the present study we explore the impact of natural ageing on the tensile properties and the in-plane anisotropy of alloy AA 6005C. Materials properties at various degrees of natural ageing are modelled with the help of a nanoscale material model NaMo, which consists of a precipitation model simulating the formation of clusters and phases upon natural ageing as input to a mechanical model simulating the evolution of yield strength and work hardening. Plastic anisotropy is modelled from the materials crystallographic texture by a visco-plastic self-consistent polycrystal-plasticity code VPSC.