Intergranularkorroosioon

Intergranularkorroosioon, also known as intergranular corrosion, is a localized form of corrosion that occurs along the grain boundaries of a metal or alloy. This type of corrosion is particularly insidious because it can significantly weaken the material without obvious external signs. It typically affects metals and alloys that are susceptible to sensitization, a process where certain elements or compounds precipitate out at the grain boundaries, making them more chemically active and prone to attack.

Commonly observed in stainless steels and some aluminum alloys, intergranular corrosion is often triggered by specific heat treatments or exposure to corrosive environments at elevated temperatures. For instance, in stainless steel, improper welding or prolonged heating can lead to the formation of chromium carbides at the grain boundaries. This depletes the adjacent areas of chromium, which is the primary element responsible for stainless steel's corrosion resistance, leaving these areas vulnerable to corrosive attack.

The consequence of intergranular corrosion is a substantial loss of mechanical strength and ductility, even if the overall metal loss is not visually apparent. This can lead to premature failure of components, especially in applications subjected to stress, such as pipelines, pressure vessels, and aircraft structures. Prevention strategies often involve controlling the alloy composition, employing specific heat treatments to avoid sensitization, or using protective coatings. Regular inspection and material selection based on the intended service environment are also crucial for mitigating this corrosion phenomenon.