Effects of pre-deformation on microstructure, mechanical properties and corrosion performance of an Al-Cu-Mg-Ag alloys

Abstract

The influence of pre-deformation on the microstructure, mechanical properties, and corrosion behavior of AA2029-T8 was investigated. The pre-deformation may potentially impede the formation of Mg-Ag clusters during the early stage of aging, altered the normal precipitation sequence of the alloy, and significantly increased dislocation density that facilitated non-uniform nucleation of S phase at dislocations, resulting in finer dispersion of precipitation. Moreover, it led to a decrease in Ω phase volume fraction and comparable aspect ratio(diameter/thickness). With increasing deformation, aging response was accelerated, leading to shorter time to peak strength but reduced plasticity. Additionally, the width of precipitate-free zone (PFZ) remained relatively unchanged with increasing pre-deformation; however, average size of grain boundary precipitates (GBPs) decreased while becoming more discontinuous. This resulted in narrowing intergranular corrosion (IGC) channels and decreased maximum corrosion depth as well as a transition from IGC to pitting corrosion behavior. These findings suggest that the mechanical properties and corrosion resistance of the alloy can be improved by increasing pre-deformation levels.