| Stainless
steel is essentially a low carbon steel which contains
chromium at 10% or more by weight. It is this addition
of chromium that gives the steel its unique stainless,
corrosion-resisting properties.
The chromium content of the steel allows
the formation of a rough, adherent, invisible, corrosion-resisting
chromium oxide film on the steel surface. If damaged
mechanically or chemically, this film is self-healing,
providing that oxygen, even in very small amounts, is
present. The corrosion resistance and other useful properties
of the steel are enhanced by increased chromium content
and the addition of other elements such as molybdenum,
nickel, and nitrogen.
There are more than 60 grades of stainless
steel. However, the entire group can be divided into
five families. Each is identified by the alloying elements
which affect its microstructure and for which each is
named.
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