Pitting Corrosion

Definition

Pitting corrosion is deep, localized metal loss that concentrates at a small region rather than thinning the surface evenly. It is how systems fail quickly.

It arises when a passive film fails locally, causing voltage to increase, resistance to decrease, and current to concentrate into a small anode. Inside the pit the chemistry diverges from the bulk water with rising acidity and concentrated chloride, making repassivation unlikely and the attack self-sustaining. Pitting is the electrochemical outcome of supercharging and of saboteurs like chloride turning uniform corrosion into localized attack.

Related concepts

Oxygen Differential Corrosion · Supercharging the Corrosion Cell · Chloride Attack

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Part of The Blueprint of Water · ⚡ electrochemistry