Corrosion is the interaction between the metal and the environment. The results in the changes in the metal properties which leads to significant functional impairment. Corrosion is the naturally occurring phenomena. It is just like all the other natural processes, corrosion of materials is unforced.
It is a uniform thinning of the metal without the localized attack. This type of corrosion can happen is the environment like the dry and wet atmosphere, acids, brines, etc.
Pitting Corrosion is a form of localized corrosion of the metal surface where the small areas can lead to the formation of the cavities. It is the most damaging form of corrosion. Pitting cause failure by penetration with a small percent of weight-loss for the entire structure.
Intergranular Corrosion is a form of attack that progresses advantageous along with the grain boundaries. The identification of the type of corrosion usually requires the microstructure examination under the microscope.
Stress Corrosion is the severe degradation mode of the failure of the nuclear, petrochemical and other industries. The stress corrosion is cracking due to the process and because of the straining of the metal due to the residual and applied stress. The stress corrosion cracking is the brittle, practically without the material loss, and the visible corrosion products. This normally occurs when one has the material such as susceptibility, involved tensile stress and an aggressive environment.
Galvanic corrosion is also known as Two-Metal Corrosion, as a result, this occurs when the alloys are electrically coupled while the exposure to an electrolyte. This metal is more reactive n the particular environment that experiences corrosion.