The destruction of metals by electrochemical (dissolving in water-air or water environment of the electrolyte) or chemical (formation of metal compounds with chemical agents high aggression) interaction with the external environment. Corrosion process in metals can develop only in some parts of the surface (local corrosion), to cover the entire surface (uniform corrosion), or to break the metal along the grain boundaries (intergranular corrosion).
The metal under the influence of oxygen and water becomes friable light-brown powder, more commonly known as rust (Fе2O3·H2O).
This process occurs in environments that are not conductors of electrical current (dry gases, organic liquid — petroleum products, alcohols, etc.), and the intensity of corrosion increases with increasing temperature — as a result, the surface of the metal oxide film is formed.