by Gary Coates, Technical Director, Nickel Institute and Dr. David Jenkinson, Director Nickel Institute Australasia.

“Stainless steel is the name given to a group of corrosion resistant and high temperature steels. Their remarkable resistance to corrosion is due to a chromium-rich oxide film which forms on the surface. When ordinary carbon steel is exposed to rain water, for example, it corrodes forming a brown iron oxide, commonly called rust, on the surface. This is not protective and eventually the entire piece of steel will corrode and be converted to rust. But when enough chromium (more than about 10%) is added to ordinary steel, the oxide on the surface is transformed – it is very thin, virtually invisible and protective in a wide range of corrosive media. This is what we call stainless steel and there are several different types, and many different grades.”