stainless steel, any one of a family ofalloy steels usually containing 10 to 30 percent chromium. In conjunction withlow carbon content, chromium imparts remarkable resistance to corrosion andheat. Other elements, such as nickel, molybdenum, titanium, aluminum, niobium,copper, nitrogen, sulfur, phosphorus, or selenium, may be added to increasecorrosion resistance to specific environments, enhance oxidation resistance,and impart special characteristics.

Most stainless steels are first melted inelectric-arc or basic oxygen furnaces and subsequently refined in anothersteelmaking vessel, mainly to lower the carbon content. In the argon-oxygendecarburization process, a mixture of oxygen and argon gas is injected into theliquid steel. By varying the ratio of oxygen and argon, it is possible toremove carbon to controlled levels by oxidizing it to carbon monoxide withoutalso oxidizing and losing expensive chromium. Thus, cheaper raw materials, suchas high-carbon ferrochromium, may be used in the initial melting operation.

There are more than 100 grades of stainlesssteel. The majority are classified into five major groups in the family ofstainless steels: austenitic, ferritic, martensitic, duplex, andprecipitation-hardening.