Intergranular corrosion

Metallic corrosion involves the loss of metal at a spot on an exposed surface. Intergranular corrosion occurs at grain boundaries. Intergranular corrosion is also called intercrystalline corrosion.

Generally, metallic corrosion involves the loss of metal at a spot on an exposed surface. Corrosion occurs in various forms ranging from uniform attacks over the entire surface to severe local attacks.

As the name implies, intergranular corrosion occurs at grain boundaries. Intergranular corrosion is also called intercrystalline corrosion. Typically, this type of corrosion occurs when chromium carbide precipitates at the grain boundaries during the welding process or in connection with insufficient heat treatment. A narrow region around the grain boundary may therefore deplete in chromium and become less corrosion resistant than the rest of the material. This is unfortunate because chromium plays an important role in corrosion resistance.

Examples of metals that are subject to intergranular corrosion:

  • Stainless steel - which is insufficiently welded or heat-treated
  • Stainless steel EN 1.4401 (AISI 316) in concentrated nitric acid




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