Initial corrosion behavior in different atmospheric environments of 6061Al alloy anodized in boron-sulfuric acid solution

The initial corrosion behavior and mechanism of 6061 aluminum alloy anodized in a solution of mixed boron- sulfuric acidswere studiedthrough outdoor exposure tests in industry-marine and northernsemi-ruralatmospheric environments at Qingdao and Beijing respectively by means of weightloss measurement, mechanical property testand morphology observation of surface andfracture surface. The results show that after exposed in the industry-marine and the northernsemi-ruralatmospheric environment for one year, the average corrosion rates of the anodized alloy decrease 43.3% and 10.1%, respectively in comparison to the naked alloy, thus the anodic treatment impedes the corrosion and this effect is much efficient in the severer environment. The break elongation of the naked alloy exposed in industry-marine environment for one year decreases 35% in comparison with the original one, but the decrease for the anodized alloy is 23%. Therefore, the anodization with boron-sulfuric acid is not enough to prevent the plasticity deterioration of the alloy; correspondingly, ductile fracture of the surface layer has changed to brittle cleavage. Nevertheless, the above results provide an important reference to the corrosion and protection of aviation materials.