Pitting Corrosion Behaviour of the 6056-T78 Aluminium Alloy

Abstract

The morphology and propagation of corrosion pits on a 6056-T78 aluminum alloy in a sulfate and chloride-containing solution have been investigated and the influence of different parameters has been studied: the passivation potential for passive film growth, the pitting potential i.e. the applied potential during the pitting process and the time for pit propagation. The passivation potential did not influence the pit morphology and the pit propagation; it only influenced the pit density. On the contrary, it was found that the pitting potential and the time had a similar influence on the pit growth. For low pitting potentials or short times, the pit depth to pit radius ratio was high (about 0.7) whereas it decreased to a value close to 0.4 for higher pitting potentials or longer times.