Filiform corrosion behavior of lightly tin (Sn)-coated steel (LTS) for welded cans was studied in relation to the free Sn coating weight (free Sn coating weight = total Sn – alloyed Sn). Filiform corrosion was found to be retarded by high cathodic polarization in the region where the free Sn coating weight was > 0.35 g/m2 and in the region where the free Sn coating weight was < 0.1 g/m2 but where the electrochemically determined chromium (Cr) coating weight was high. In the region where the free Sn coating weight was 0.1 to 0.35 g/m2, microcells were formed by the coupling of free Sn and the tin-iron alloy below the lacquer film, resulting in acceleration of filiform corrosion.

Subject
Coatings, Materials, Corrosion resistant alloys, Corrosion currents, Metal surfaces, Cathodic polarization curves, Acidity, Epoxy coatings, Anodic reactions, Steel, Corrosion resistance, Alloys, Filiform corrosion
Keywords:
chromium, corrosion resistance, filiform corrosion, free tin, microcell, oxygen overpotential, polarization curve, tin, tin-free steel, tin-iron alloy
NACE International
1994
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