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E: ssas@bssa.org.uk
The corrosion resistance of stainless steel arises from a passive, chromium-rich, oxide film that forms naturally on the surface of the steel. Although extremely thin at 1-5 nanometres, (i.e. 1-5 x 10-9 metres), thick, this protective film is strongly adherent, and chemically stable, (i.e. passive), under conditions which provide sufficient oxygen to the surface. The affects of alloying elements nickel, molybdenum and nitrogen on localised forms of corrosion attack is discussed. The mechanisms include crevice corrosion, pitting corrosion, Intercrystalline, (or intergranular), corrosion, (ICC), stress corrosion cracking, (SCC), and galvanic, (bi-metallic), corrosion and are often associated with chlorides or acid conditions.
SSAS4.01-Introduction to Corrosion Resistance