Like all steels, stainless steels are iron-based alloys. They are considered a special class of steels because of their high alloy content and their special properties as compared to plain-carbon and low-alloy steels. As their name indicates, this class of metals has good corrosion resistance, which comes from the formation of an adherent chromium-oxide film on the surface of the metal. This film, though very thin, prevents the degradation of the base iron. On the whole, stainless steels have fairly high strength and relatively good ductility.