Question

what combination of metals is the iron pillar near Qutab Minar in Delhi made of?

Answer 1

The Iron pillar at the Qutub Minar is composed by almost 98% pure wrought iron and small amount of phosphorus in the iron structure. The amazing fact for iron pillar at delhi is that still after many years it has not rusted, most likely because of formation of a thin film of magnetic oxide (Fe₃O₄) on the surface, as a result of finishing treatment given to the pillar, painting it with a mixture of different salts, then heating and quenching.