Handy Guide of Stainless

Properties of stainless

Stainless steel has been known as less rusty steel as its name shows.
The property of stainless has been due to its oxide film that covers stainless surface.
This oxide film has generally been called as passivate film that is created when chrome, being ingredient of stainless, is exposed and oxidized by the oxygen in the air.
That is why the film can regenerate in the air, even if the film gets any damage by chance.
Since the stainless steel has been covered by this remarkable film, stainless steel retains the superior corrosion resistance, in other word hard to be corroded.

Stainless steel is a general term of the steel of ferrous metal being superior in corrosion resistance that contain about 11% and more chromium and in order to improve its corrosion resistance and mechanical feature, alloy element such as nickel and molybdenum are to be added.
Then highly protective film called passivate film is formed on the surface.
This passivate film is an oxide compound (hydroxide) that contains very thin iron and chromium and the film is extremely thin as thin as being below one hundredth of 1μ.
Therefore, though the film is very vulnerable mechanically and base naked metal will easily be exposed, the film will soon be recovered by the contact with oxygen and vapor and thus regains the corrosion resistance.

• The image of oxide film recovery
• Composition of
  oxide film