It is the deterioration of a metal with loss of properties because of its interaction with the surrounding environment. It is produced by the loss of material on the surface of a piece by chemical action with exchange of electrons between two chemical species (electrochemical phenomenon).
Corrosion may occur by chemical oxidation-reduction reaction or by dissolution of material in an electrolyte (such as moisture).
The consequences of generalized corrosion are the weight loss of the material and the dimensional variation. In localized corrosion, the consequence may be losses of mechanical characteristics.
Depending on the main mechanism of corrosion different types are defined: galvanic, generalized, by cracks, microbiological, pitting or stress corrrosion.