Corrosion behaviour of AA6082 Al-Mg-Si alloy extrusion: Recrystallized and non-recrystallized structures

• Recrystallized region in AA6082 alloy extrusion is susceptible to intergranular corrosion. • Non-recrystallized region is susceptible to both intergranular and intragranular corrosion. • Corrosion morphology is related to crystallographic defect density. • Corrosion penetration rate and propagation path are related to grain structure. • Heavily deformed non-recrystallized region is more susceptible to corrosion. In the present study, the corrosion behaviour of AA6082 Al-Mg-Si alloy extrusion, consisting of a recrystallized surface region and non-recrystallized fibre structure core, is investigated. It is found that the corrosion penetration rate and propagation path are closely related to grain structure and local plastic deformation. Corrosion morphology changes from intergranular corrosion in recrystallized region to both intergranular and intragranular corrosion of the heavily deformed subgrains in non-recrystallized region. Further, local plastic deformation is quantified by electron backscatter diffraction and transmission Kikuchi diffraction and correlated to corrosion propagation path.