Effects of pre-stretch on microstructure, mechanical properties and corrosion resistance of 2A14 aluminum alloy

The microstructure, mechanical properties and corrosion behaviors of the peak-aged 2A14 aluminum alloys subjected to pre-stretch prior to artificial aging were investigated. The results indicate that the hardness and strength of the peak-aged alloy can be greatly enhanced via introducing pre-stretch due to the formation of dense and finer θ′ precipitates with dispersed distribution in alloy matrix. Pre-stretch prior to peak aging evidently enhances the peak aging hardness and shortens the peak aging time of the alloy. A pre-stretching degree of 7.5% leads to a distinct inhomogeneous distribution of θ′ phase, which decreases the ultimate tensile strength. As pre-stretching degree increases, the plasticity, impact toughness and exfoliation corrosion (EXCO) resistance of the peak-aged alloy all gradually decrease, but its resistance to intergranular corrosion (IGC) increases and then decreases.