Galvanic Corrosion Galvanic corrosion is a very common form of corrosion that results from contact between dissimilar metals. The process is driven by a difference in the electrode potential of the two metals and the difference in the size of the dissimilar metals. Galvanic corrosion is responsible for much of the corrosion in military aircraft
Pitting Pitting is another form of corrosion that results when an electrochemical reaction occurs on a metal that has a large surface area relative to the surrounding metals. The rate of attack (acidification) on this metal is greater, thus corrosion occurs at a much faster rate.
Crevice Corrosion Crevice corrosion is a form of localized corrosion that occurs near an area of a metal surface adjacent to another metal that is sheltered from full exposure to the environment. The reaction between the oxygen in the crevice and the rest of the metal causes a gradient in the oxygen concentration, and thus a difference in electrode potentials and a flow of current.
Intergranular Corrosion Intergranular corrosion occurs at or adjacent to the grain boundaries of a metal or alloy. The actual mechanism of the corrosion varies with metal system. This attack at the grain boundaries can cause entire metal grains to become dislodged. Leakage of corrosive fluids, loss of effective cross sectional area, and mechanical failure can result.
Erosion-Corrosion Erosion-corrosion, as its name suggests, results from the actions of corrosion and erosion in the presence of a moving corrosive liquid, causing accelerated loss of the metal.
Environmental Cracking Environmental Cracking results from the combined action of a tensile stress and a corrosion reaction in an environment susceptible to cracking. This form of corrosion often causes an otherwise ductile metal to fail. Failures resulting from environmental cracking are often disastrous because they occur in metals that usually have good corrosion resistance.
Stress Corrosion Cracking Stress Corrosion Cracking, similar to environmental cracking, results from the combined effects of a tensile stress and a specific environment. (Much attention has been paid to determining which environments that metals become susceptible to stress corrosion cracking.)
