Effect of creep-aging processing on corrosion resistance of an Al–Zn–Mg–Cu alloy

• Corrosion resistance of Al–Zn–Mg–Cu alloy is sensitive to creep-aging processing.
• The increase of applied stress can enhance the corrosion resistance.
• The increased temperature first increases and then decreases corrosion resistance.
• Discontinuous GB precipitate and narrow PFZ improve can corrosion resistance.

Creep-aging forming, combining both the aging treatment and forming process, has recently drawn much attention of researchers. In this study, the effects of creep-aging processing on the corrosion resistance of an Al–Zn–Mg–Cu alloy are studied. Results show that the corrosion resistance of the studied Al–Zn–Mg–Cu alloy is sensitive to creep-aging processing parameters (creep-aging temperature and applied stress). With the increase of creep-aging temperature, the corrosion resistance first increases and then decreases. Increasing the applied stress can deteriorate the electrochemical corrosion resistance and improve the exfoliation corrosion resistance. The creep-aging processing can change the size and distribution of precipitates in the aluminum matrix, which significantly affects the corrosion resistance. The discontinuous grain boundary precipitates and narrow precipitate-free zones can enhance the corrosion resistance.