Which corrosion damage is beyond minor corrosion discoloration or etching stage. Pits are present and visible to the naked eye.

• A. Major Corrosion
• B. Pitting
• C. Minor Corrosion
• D. Etching

Answer: (B)

The key idea is distinguishing how corrosion appears on a surface. Minor corrosion means only surface changes like discoloration or a light etch. When pits form that you can see without magnification, you’re dealing with pit corrosion, a localized form that is more serious than simple surface changes. Pitting creates small cavities that can weaken the material even if the overall surface looks largely intact, and visible pits confirm that corrosion has progressed beyond the minor stage. Major corrosion would imply more extensive material loss, which isn’t indicated here, and etching describes surface patterns rather than actual pits. So seeing pits visible to the naked eye identifies pit corrosion.