Influence of grain structure on anisotropic localised corrosion kinetics of AA7xxx-T6 alloys

Abstract

Aluminium alloys of the AA7xxx series can have very high strength but are generally susceptible to localised corrosion. In the present study, the localised corrosion kinetics for different plates of AA7xxx-T6 were investigated in different orientations, using the foil penetration method. Multiple breakdown potentials were observed on the polarisation curves and they were independent of plate orientation. The grain size and aspect ratio were measured for each plate and were shown to be important factors for the localised corrosion growth kinetics. Anisotropic localised corrosion kinetics were observed on rolled plates owing to the microstructural anisotropy and equiaxed material had localised corrosion kinetics that were independent of orientation.

Keywords

LOCALISED CORROSION KINETICS AL ALLOY MICROSTRUCTURE GRAIN ASPECT RATIO BREAKDOWN POTENTIAL

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