Intergranular corrosion occurs where?

Intergranular corrosion occurs where?

• A. Within the grains
• B. On the surface
• C. Along the grain boundaries
• D. In coatings

Answer: (C)

Intergranular corrosion is corrosion that travels along the interfaces between individual crystals in a metal. Those grain boundaries are regions of higher energy and can become sites where impurities segregate or precipitates form, creating local differences in electrochemical potential. In stainless steels that have been sensitized, chromium carbides can precipitate at the boundaries, depleting chromium in adjacent areas and making the boundaries more anodic relative to the grain interiors. This sets up microcells that drive corrosion along the boundaries, so the attack follows the grain edges rather than cutting through the grains themselves. It’s not simply surface corrosion, nor is it limited to coatings, and it’s not confined to the inside of a grain.

Intergranular corrosion is corrosion that travels along the interfaces between individual crystals in a metal. Those grain boundaries are regions of higher energy and can become sites where impurities segregate or precipitates form, creating local differences in electrochemical potential. In stainless steels that have been sensitized, chromium carbides can precipitate at the boundaries, depleting chromium in adjacent areas and making the boundaries more anodic relative to the grain interiors. This sets up microcells that drive corrosion along the boundaries, so the attack follows the grain edges rather than cutting through the grains themselves. It’s not simply surface corrosion, nor is it limited to coatings, and it’s not confined to the inside of a grain.