Question

Why iron pillar at delhi has not been rusted till now?

Answer 1

The pillar has attracted the attention ofarchaeologists and materials scientists and has been called "a testament to the skill of ancient Indian blacksmiths" because of its high resistance to corrosion.[1] The corrosion resistance results from an even layer of crystalline iron hydrogen phosphate hydrate forming on the high phosphorus content iron, which serves to protect it from the effects of the local Delhi climate.[2]

The pillar weighs over 6,000 kg, and is thought to have originally been erected in what is nowUdayagiri by one of the Gupta monarchs in approximately 402 CE, though the precise date and location are a matter of dispute.[3] It was transported to its current location in 1233 CE.[4]