Filiform corrosion behaviour on machined AA7150 aluminium alloy

The microstructure and the filiform corrosion behaviour of machined AA7150 aluminium alloy were investigated using scanning and transmission electron microscopies combined with potentiodynamic polarization and filiform corrosion testing, respectively. It is found that the grain refinement, redistribution of alloying elements, and elements segregation at grain boundaries are evident within the near-surface region on the machined AA7150 aluminium alloy. The corrosion susceptibility of machining introduced near-surface deformed layer is significantly improved caused by the modified microstructure associated with severe deformation. Filiform corrosion resistance on the machined surface is obviously decreased, due to the surface roughness associated with machining tracks and the presence of the electrochemically more active near-surface deformed layer introduced by machining.