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Iron pillar in India exposed to the elements for over 1,600 years hasn't rusted

• pavel_lishin 2y ago
  > They found that the pillar, primarily made of wrought iron, has a high phosphorus content (about 1%), and lacks sulfur and magnesium, unlike modern iron. Additionally, ancient craftsmen used a technique called “forge-welding.” > That means they heated and hammered the iron, keeping the high phosphorus content intact, a method uncommon in modern practices. > Archeo-metallurgist R. Balasubramaniam, who authored the report, said that this unconventional approach contributed to the pillar’s enduring strength. > A thin layer of “misawite,” a compound of iron, oxygen and hydrogen, was also found on the pillar’s surface, he said. This layer is formed catalytically by the presence of high phosphorus in the iron and the absence of lime, thus further enhancing the pillar’s durability.