Stainless steel is an alloy of iron (Fe) and chromium (Cr), with a controlled amount of carbon (C). They are a family of steels containing a minimum of 11% chromium, whose primary property is that of corrosion resistance. If 11% of more chromium is added, a protective, passive film will form. The higher the chromium content, the stronger the passive film. Carbon steel generally contain .3% to 4% chromium

Other elements such as molybdenum (MO) and Nitrogen (N) further strengthen the passive film and improve corrosion resistance. If the passive film is removed or damaged, it will spontaneously re-form in the presence of air or water.