Sensitization in stainless steels increases susceptibility to what type of corrosion?

• A. Intergranular corrosion susceptibility increases
• B. Uniform corrosion increases
• C. Pitting corrosion decreases
• D. Hydrogen embrittlement increases

Answer: (A)

Sensitization causes chromium carbides to form at grain boundaries in stainless steels when exposed to certain temperatures. This pulls chromium out of the nearby areas, creating chromium-depleted zones along the grain boundaries. Those boundaries then lose their protective passive film and become more anodic than the surrounding metal, so corrosive attack concentrates there. That makes the steel particularly prone to intergranular corrosion. Uniform corrosion is a general thinning, which isn’t specifically driven by sensitization; pitting is localized attack due to passive film breakdown, not the grain-boundary pathway created by sensitization; and hydrogen embrittlement is a different failure mechanism. So the increased susceptibility is specifically to intergranular corrosion.