General Pitting of Carbon Steel

Pitting is defined as localized corrosion attack occurring on openly exposed metal surfaces in the absence of any apparent crevices.

Pitting corrosion occurs when a protective surface layer breaks. After local breakdown of the film/layer, an anode forms where the film breaks down.   The unbroken film (or protective layer) acts as a cathode. Localized attack and pits develop at the anodic spots. The electrolyte inside the growing pit may become very aggressive has metal ions migrate out and anions, such as chlorides, migrate into the pit.

Robert R. Odle, Ph.D.   robert@metallurgicalviability.com, 443-616-4339

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