Stainless steel represents a group of high temperature and corrosion resistant steels. Stainless steel’s exceptional resistance to corrosion is due to a high chromium oxide film which is formed on the surface. Normally when carbon steel comes in contact with water, it corrodes forming a brown iron oxide called rust on the surface. Eventually steel will corrode and be convert to rust. But when sufficient chromium (more than about 10%) is added to ordinary steel, transforming the oxide on the surface it is very thin,protective and virtually invisible in a wide range of corrosive media. This is called stainless steel and there are different types and grades under this group.