British metallurgist Harry Brearley developed stainless steel in 1913 searching for a better lining for cannons. He discovered that chromium had the ability to create an oxide lining, and that steel made from iron and chromium resisted many corrosive chemicals.
Stainless steel coating is a thin, transparent film of iron oxide and chromium. This prevents soap, food, water, and air from getting to the metal below and eating it away. Stainless steel is very sanitary since its coating is so smooth. Bacteria, fungi, and dirt have nowhere to hide and are easily washed away. For this reason, commercial kitchen surfaces and cooking equipment are often made of stainless steel.
Stainless steel can “heal” itself! If scratched or nicked, the protective oxide immediately recoats the damaged area. Because of its great ability to resist rusting , it is an ideal material for cutlery, pots and pans.
Stainless steel differs from carbon steel by the amount of chromium present. Unprotected carbon steel rusts readily when exposed to air and moisture. This iron oxide film (the rust) is active and accelerates corrosion by forming more iron oxide; and, because of the greater volume of the iron oxide, this tends to flake and fall away.
Stainless steels contain sufficient chromium to form a passive film of chromium oxide, which prevents further surface corrosion by blocking oxygen diffusion to the steel surface and blocks corrosion from spreading into the metal’s internal structure, and, due to the similar size of the steel and oxide ions, they bond very strongly and remain attached to the surface.
Stainless steel’s resistance to corrosion and staining, low maintenance and familiar lustre make it an ideal material for many applications. There are over 150 grades of stainless steel, of which fifteen are most commonly used. The alloy is milled into coils, sheets, plates, bars, wire, and tubing to be used in cookware, cutlery, household hardware, surgical instruments, major appliances, industrial equipment (for example, in sugar refineries) and as an automotive and aerospace structural alloy and construction material in large buildings. Storage tanks and tankers used to transport orange juice and other food are often made of stainless steel, because of its corrosion resistance. This also influences its use in commercial kitchens and food processing plants, as it can be steam-cleaned and sterilized and does not need paint or other surface finishes.
Stainless steel is used for jewelry and watches with 316L being the type commonly used for such applications. It can be re-finished by any jeweler and will not oxidize or turn black.
Some firearms incorporate stainless steel components as an alternative to blued or parkerized steel. Some handgun models, such as the Smith & Wesson Model 60 and the Colt M1911 pistol, can be made entirely from stainless steel. This gives a high-luster finish similar in appearance to nickel plating. Unlike plating, the finish is not subject to flaking, peeling, wear-off from rubbing (as when repeatedly removed from a holster), or rust when scratched.
Some automotive manufacturers use stainless steel as decorative highlights in their vehicles.