Corrosion Resistance at Defect of Paint Film for Sn-Bearing Steel

The corrosion resistance at defect of paint film for Sn-bearing steels exhibiting superior atmospheric corrosion resistance under high chloride content environments was investigated by an accelerated corrosion test. It was found that the delaminated area and corrosion depth around the defect of paint film for the Sn-bearing steels after the test were drastically suppressed, comparing with that for carbon steels. Even on rusted and Cl--contaminated surfaces simulating insufficient surface preparation when repairing the paint film, the Sn-bearing steel showed the superior corrosion resistance. Sn ion dissolved at the defect by anodic reaction can inhibit the anodic dissolution of Fe.