intergranular corrosion
The localized spots of corrosion show up along the grain boundaries of a metal and are called intergranular corrosion. Such corrosion usually occurs due to chemical segregation or impurities at the grain boundaries as a result of which the material fails without much damage to the surface.
Key Features:
- Mechanism of Corrosion: Depletion or enrichment of a particular element at the interface grain boundaries. Those metals which have been subjected to improper heat treatment typically get exposed to corrosive environments. It generally affects stainless steels, aluminum alloys, and nickel-based alloys.
- Affect Property: Structural Integrity: It weakens the metal by creating pathways for propagation of cracks through the grain boundaries.
- Varied Challenges & Applications: Aerospace & Marine: Parts exposed at high temperatures and corrosive media, such as components within aircrafts and ships, are susceptible to intergranular corrosion. Pipelines & Chemical Processing: Stainless steel pipes and equipment in chemical plants can suffer if heat-treated improperly.
In preventing intergranular corrosion, methods used by manufacturers include stabilizing alloys with titanium or niobium, performing the right heat treatment (solution annealing) and selecting suitable corrosion-resistant grades of metal.