Stainless steel

In metallurgy, stainless steel (inox) is defined{{ref|AISI}} as a ferrous alloy with a minimum of 10.5% chromium content. The name originates from the fact that stainless steel stains, or rusts, less easily than ordinary steel. Stainless steel has higher resistance to oxidation (rust) and corrosion in several environments.

Related Topics:
Metallurgy - Ferrous - Alloy - Chromium - Steel - Oxidation - Rust - Corrosion

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High oxidation resistance in air at ambient temperature is normally achieved with additions of more than 12% (by weight) chromium. The chromium forms a layer of chromium (III) oxide (Cr2O3) when exposed to oxygen. The layer is too thin to be visible, meaning the metal stays shiny. It is, however, impervious to water and air, protecting the metal beneath. Also, when the surface is scratched this layer quickly reforms. This phenomenon is called passivation by materials scientists, and is seen in other metals, such as aluminium. When stainless steel parts such as nuts and bolts are forced together, the oxide layer can be scraped off causing the parts to weld together. When disassembled, the welded material may be torn and pitted, an effect that is known as galling.

Related Topics:
Air - Temperature - Chromium - Oxygen - Water - Passivation - Materials scientists - Aluminium - Nut - Bolt - Weld

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