Intergranular corrosion of AA6082 Al–Mg–Si alloy extrusion: The influence of trace Cu and grain boundary misorientation.

In the present work, the influence of trace level Cu on intergranular corrosion (IGC) in AA6082 Al–Mg–Si alloy is studied using correlative accelerated corrosion testing and high resolution electron microscopy. Further, grain boundary structure and its correlation to IGC are also investigated using electron backscatter diffraction (EBSD) and transmission Kikuchi diffraction (TKD). It is found that in AA6082-T6 alloy with very low Cu content (0.06 wt%), about 13% of high angle grain boundaries have Al 2 Cu precipitates, which promotes IGC at the grain boundaries. • In AA6082-T6 alloy with 0.06 wt % Cu, Al 2 Cu precipitates are present at 13% of high angle grain boundaries. • Low angle grain boundaries in the AA6082-T6 alloy are almost free of precipitates. • The presence of Al 2 Cu precipitates at high angle grain boundaries increases susceptibility to IGC in acidified NaCl solution. • Low angle grain boundaries show low susceptibility to intergranular corrosion in acidified NaCl solution. [ABSTRACT FROM AUTHOR]