The effect of chromate on the pitting susceptibility of AA7075-T651 studied using potentiostatic transients

The effect of chromate on metastable pitting of AA7075-T651 as determined via potentiostatic polarisation is reported. A systematic study of metastable pitting and its correlation with stable pits was conducted in various concentrations of sodium chromate (Na2CrO4), revealing the metastable pitting rate was able to provide a quantitative metric for pitting corrosion. The size and number of metastable pits decreased significantly in the presence of chromate. The present study is intended as a general baseline for the assessment of future chromate replacement technologies, as elaborated herein.