One obvious breakdown potential, Epit, exhibited in all the curves of samples abraded with abrasive papers of 600 grit, 200grit and 5000grit. The Epit was found to be much higher than the corrosion potential (Ecorr), which indicated that all of the sanded samples exhibited passivation behavior and showed clear passive ranges. With increasing grit number from 600 to 5000, a shift in Ecorr and Epit to more noble values was detected, while the shift in Epit (about 200mV) was relatively larger than that in Ecorr (about 86 mV). Therefore, with increasing grit number from 600 to 5000, the passive ranges of 2A12 aluminum alloy increased