Recently, stamped wrought Al alloy 6451 is implemented to produce automotive enclosures such as tailgates, which often suffer harsh environment during service. The corrosion resistance of Al alloy 6451 needs to be improved essentially. In this study, oxide coatings were applied on stamped wrought Al 6451 with the help of Plasma Electrolytic Oxidation (PEO) technique to enhance its corrosion resistance. A potentiodynamic polarization test was conducted to investigate corrosion resistances of uncoated and coated samples. The results of the potentiodynamic polarization tests revealed that the corrosion resistances of uncoated, thin-coated, and thick-coated Al 6451 samples were 7282.5 Ω·cm2, 11583.3 Ω·cm2, and 41,151 Ω·cm2, respectively. These findings clearly demonstrate that the growth of the coating layer significantly enhances the substrate’s ability to withstand corrosive environments. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) were employed to investigate the variation of surface morphologies and chemical composition of the PEO coatings. The SEM observation indicated that the coating layers exhibited a smooth surface compared to the as-coated condition, and pitting corrosion occurred on the corroded coating surfaces. The EDX spectra showed a reduction in the calculated Al/Si intensity ratio before and after the corrosion tests.
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