Corrosion caused by the atmosphere on 1050 aluminum in the Basque country

After exposing aluminum samples to five atmospheres (rural industrial and marine-industrial) in the Basque Country, the number and depth of the pits formed for different exposure times were measured. During the four years of exposure, sulphur dioxide and chloride ion levels, together with relative humidity and temperature, were determined. From these results, a linear increase of the pit density with time and a bilogarithmic one of the pit depth with time, were determined. An important effect of the synergistic action of SO₂ and chloride in the formation and growth of pits was found. A statistical treatment is proposed to predict the pit density to be formed when the 1050 aluminum is exposed to the atmosphere.