Corrosion may affect the entire surface of the metal in contact with the aggressive medium (general corrosion) or only specific points around (localized corrosion) or at high temperatures appear.
Crevice corrosion starts in caves or crevices or confined spaces conducive to the accumulation of chemical species and the acidification of the environment locally leading to the breakdown of the passive layer allowing corrosion of the alloy.
Stress corrosion cracking is starting out in a corrosive environment after a long incubation period. This is mainly due to the simultaneous action of a corrosive environment and a state of stress.
Intercrystalline or intergranular corrosion occurs in the form of chemical attack at the grain boundaries of the areas that have been heated to between 500 and 800 ° C, said heating having a driven sensitization (phenomenon caused by the welding operation on the affected area HAZ heat.
High temperature corrosion following different mechanisms depending on whether the act in oxidizing or reducing atmospheres.