The contribution of hydrogen to the corrosion of 2024 aluminium alloy exposed to thermal and environmental cycling in chloride media

This work is focused on the role of hydrogen in corrosion damage induced by the cyclic exposure of 2024 aluminium alloy to chloride media with air emersion periods at room and/or negative temperatures. Various analysis and microscopic observation techniques were applied at intergranular corrosion defects. A mechanism involving the contribution of hydrogen to the degradation of the alloy mechanical properties is presented. Several consecutive stress states appear during cycling, resulting from volume expansion of the electrolyte trapped in the intergranular defects during emersion phases at −20 °C. These stress states lead to hydrogen diffusion, transport and trapping.

► We examine the role of hydrogen in corrosion mechanisms of AA 2024.
► Cyclic thermal exposures of AA 2024 to chloride media are considered.
► We demonstrate that hydrogen is produced during the corrosion reactions.
► A volume expansion of electrolyte trapped in corrosion defects is observed at −20 °C.
► Hydrogen diffusion, transport and trapping occur due to several stress states.