IGC situation can happen in otherwise corrosion-resistant alloys, when the grain boundaries are depleted, known as grain boundary depletion, of the corrosion-inhibiting elements such as chromium by some mechanism. In nickel alloys and austeniticstainless steels, where chromium is added for corrosion resistance, the mechanism involved is precipitation of chromium carbide at the grain boundaries, resulting in the formation of chromium-depleted zones adjacent to the grain boundaries (this process is called sensitization). Around 12% chromium is minimally required to ensure passivation, a mechanism by which an ultra-thin invisible film, known as passive film, forms on the surface of stainless steels. This passive film protects the metal from corrosive environments. The self-healing property of the passive film make the steel stainless. Selective leaching often involves grain boundary depletion mechanisms.
ALS conducts IGC testing for Practice A,B,C,E, and Fas per ASTM A262 and also as per DIN EN ISO 3651-2. We have more than 5hot plate setups which can be deployed simultaneously for these tests.