Effect of rolling temperature on mechanical properties and corrosion resistance of Al-Cu-Mg-Ag alloy

The Al-Cu-Mg-Ag alloy with a low Cu/Mg ratio was hot rolled at different temperatures (410 °C, 440 °C, 470 °C) following by solution and under-aged treatment to reveal the effect of hot rolling temperature on microstructures, mechanical and corrosion properties. This work was investigated by transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) and electron backscattering diffraction (EBSD) techniques. The results showed that the tensile strength of the alloy slightly reduced by only 1.5% when the rolling temperature decreased from 470 °C to 410 °C, but greatly improved its corrosion resistance. The strengthening of the alloy mainly came from the synergistic effect of solution strengthening and cluster strengthening. The corrosion susceptibility of the alloy hot rolled at a lower temperature was suppressed, due to the increase in the low-angle grain boundary (LAGB) fraction and the discontinuous distribution of the precipitated S phases at the grain boundary. It was also found that Ag atoms were segregated at the grain boundary by mapping.