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+2 1. freedooom commented 10 years ago on video 10 Unexplained Discoveries

as a materials scientist i feel obliged to tell this, the first 2 aren't mysteries let me explain them briefly:

- Damascus steel is basically steel with high carbon content (carbon makes steel harder) harder alloys like the alloys used for making drill bits don't get damaged as easily so it can cut through other swords much like drill bits drilling through other materials

-the iron pillar of delhi has some second phase particles with low chemical activity (they probably got mixed in from the slag by accident*) these particles create a thin film around it and it protects the pillar much like the addition of 12% chromium making steel stainless.

*I don't think they "knew" how to make corrosion resistant steel back then because if they did they would have used it to make some cutlery as well