Question

why the Iron Pillar in Delhi has not rusted for years​

Answer 1

Answer:

it is resistant to corrosion due to the formation of a thin protective passive film with high phosphorus content.

Answer 2

Explanation:

the Corrosion Resistance property of the Delhi Pillar is due to: (i) the purity of its iron; (ii) high phosphorus; (iii) low sulphur; (iv) absence of any other metal; (v) cinder coating formed on the surface; (vi) better forge welding; (vii) drier and uncontaminated atmospheric condition; and (viii) mass metal effect