Which corrosion type involves attack along grain boundaries due to sensitization?

Which corrosion type involves attack along grain boundaries due to sensitization?

• A. Intergranular Corrosion
• B. Uniform Attack
• C. Pitting
• D. Crevice

Answer: (A)

Attack along grain boundaries caused by sensitization is intergranular corrosion. When certain stainless steels are exposed to temperatures that cause chromium carbide precipitates to form at the grain boundaries, chromium is locally depleted near those boundaries. This reduces corrosion resistance specifically at the boundaries, so corrosive media attack travels along the grain boundaries rather than through the grain interiors. That distinctive path—along the boundaries between grains—defines intergranular corrosion. In contrast, uniform attack wears the surface evenly, pitting forms isolated small pits, and crevice corrosion happens in confined spaces where chemistry inside the crevice differs from the outside environment.

Attack along grain boundaries caused by sensitization is intergranular corrosion. When certain stainless steels are exposed to temperatures that cause chromium carbide precipitates to form at the grain boundaries, chromium is locally depleted near those boundaries. This reduces corrosion resistance specifically at the boundaries, so corrosive media attack travels along the grain boundaries rather than through the grain interiors. That distinctive path—along the boundaries between grains—defines intergranular corrosion. In contrast, uniform attack wears the surface evenly, pitting forms isolated small pits, and crevice corrosion happens in confined spaces where chemistry inside the crevice differs from the outside environment.