Stainless Steel

Etymology of Stainless Steel

STAIN + LESS STEEL

Stainless steel means steel which is hardly got rusty (A word, stain meaning rust plus suffix “less” meaning denial)
(Chinese character : 不銹鋼 )

History of Stainless Steel

Motive for Development

Development of integrated steel mill technology enabled the mass production of iron from the end of 19th century to the early 20th century. But rust on iron was a problem. Research was been carried out to solve this problem, such as surface treatment, electric protection and additive of alloy, including research for control of rust by addition of double alloy elements which motivates the development of stainless steel.

Reason why Stainless Steel is Hardly Got Rusty

When stainless steel maintains chrome(Cr) more than 12%, it naturally forms thin Cr₂O₃ layer (10~50 Å) (passivity layer) to protect steel from the entrance of oxygen.

Structure of Passivity Layer

Classificaction	Normal Carbon Steel	Stainless Steel
Configuration	Fe-oxide	Cr₂O₃
Coating Feature	Oxygen easily enters from the outside since it has thick and perforate coation.	Oxygen hardly enters from the outside since it has thin and close coating.