Crack Formation and Corrosion Behavior of 6061 Al Alloy in Sulfuric Acid

The 6061 aluminum alloys (AA6061) specimens were anodized in the sulfuric acid solution. The crack formation and corrosion behavior of the AA6061 oxide films were investigated in a wide range of sulfuric acid concentration (1 similar to 5 M) and current density (0.3 similar to 3 A/dm(2)). A number of cracks were formed on the surface of the anodized AA6061 oxide film at a high electrolyte concentration of 5 M and low current density of 0.3 A/dm(2). Moreover, increasing current density could suppress crack formation at a high concentration of 5 M while decreasing electrolyte concentration was also helpful for eliminating cracks at a constant current density of 1 A/dm(2). The more the cracks, the higher the corrosion current was. Suppressing crack formation was crucial for promoting corrosion resistance of the AA6061 film with less corrosion current. The best corrosion resistance of the anodized film with I-corr=l.433x10(-10) A/cm(2) was obtained at a current density of 1 A/dm(2) and a concentration of 1 M sulfuric acid, that could be potentially used for long-term anti-corrosion coatings on many AA6061 alloy products.