Effects of re-solution and re-aging treatment on mechanical property, corrosion resistance and electrochemical behavior of 2196 Al-Cu-Li alloy

Abstract

The effects of re-solution (RST) and re-aging (RA) treatment on the mechanical property, microstructure, corrosion resistance and electrochemical behavior of 2196 Al-Cu-Li alloy were investigated by tensile testing, conductivity testing, intergranular corrosion and electrochemical corrosion testing. The results show that RST and RA treatment can improve the corrosion resistance without sacrificing the strength compared to T6 temper. The aging precipitation process is reversible, and the number and distribution of δ’, T1 and θ’ precipitates can be effectively regulated by the RA treatment, so that the strength of the alloy approximately reaches the level of T6 temper and the ductility is improved. The corrosion mode of the alloy changed from pitting into intergranular corrosion during RST and RA treatment. The coarsening and discontinuous distribution of grain boundary precipitates as well as the increase of precipitate-free zone (PFZ) width inhibit the generation and propagation of stress corrosion cracking and thereby improve the corrosion resistance of the alloy. The increase of Cu content in grain boundary reduces the electrochemical corrosion sensitivity of the alloy. The optimal process parameters of RST and RA treatment for 2196 Al-Cu-Li alloy are finally determined to be 515 °C for 90 min and 170 °C for 24 h.

Keywords

• Al-Cu-Li alloy
• Re-solution and re-aging
• Mechanical property
• Corrosion resistance
• Electrochemical behavior