The mechanism
for intergranular corrosion in ferritic stainless
steels is largely accepted as being the same as that
in austenitic stainless steels. Chromium compounds
precipitate at grain boundaries, and this
causes chromium depletion in the grains immediately
adjacent to the boundaries (Ref 22, 23).
This lowering of the chromium content leads
to increased corrosion rates in the oxidizing
solutions usually used to evaluate intergranular
corrosion.