Effect of Processing on Grain Size and Corrosion of AA2024-T3

Recent works on high-purity materials have indicated that microstructural modification via grain refinement can alternately reduce or enhance corrosion, depending on the specific material-environment combination. Generally, however, a paucity of information exists in understanding how microstructural alteration and processing, in combination with grain refinement, affects corrosion. In this work, the effect of microstructural refinement on an alloy containing a high number density of precipitates and intermetallics is explored. Grain-refined AA2024-T3 (UNS A92024) samples were produced through severe plastic deformation processes and their corrosion response was compared to control samples of commercial ingot and sheet across the pH range. Microstructure and grain size were characterized using a combination of electron backscattered diffraction and transmission electron microscopy. It is revealed that there is a difference in corrosion between the specimens (which possess nearly the same bulk chemistry) as based on anodic potentiodynamic polarization, current transient, and exposure/profilometry experiments in sodium chloride (NaCl) electrolytes. However, in all cases, the effect is dominated by the environment, micro-chemical differences, and grain size.