Materials and Corrosion 7/2013



The upper photograph shows a part of a fastening construction of a photovoltaic system after 3 years exposure to marine atmosphere. The profiles of the frame consist of the aluminum alloy EN AW-6063 (Al Mg0.7Si) and the bolt connections are made of stainless steel with the material number 1.4301 (XCrNu18-10). The lower photograph shows a part of the bolt connection after cleaning and pickling. In the area shown here, due to insufficient cleaning effects by rain and due to new loading and accumulation of chloride ions bimetallic corrosion between the material combination stainless steel/aluminum alloy occurred. The corrosion effects concerned relate solely to the aluminum surfaces. In the area influenced by bimetallic corrosion the surface of the aluminum alloy suffers significant material loss due to pitting corrosion. (Photo: Courtesy of BAM)