Question

What is the usual direction for the growth of pits?

(a) Vertically downwards

(b) Vertically upwards

(c) Horizontally sideward

(d) Any primary direction

The question was asked during an online interview.

This interesting question is from Eight Forms in section Eight Forms of Corrosion of Corrosion Engineering

Answer 1

Right answer is (a) Vertically downwards

The best explanation: Pits usually grow in the direction of gravity i.e. vertically downwards. Gravitational force holds the corrosive solution vertically downwards in a cavity, that makes the pit growth downwards. And very a smaller number of pits grown vertically upwards.