We all know that in terms of swords a sales pitch about a 50 on the rockwell hardness scale for the blade, something or another about high carbon spring steel, hand casted, blah blah blah is about right.
However, what about for armor? Chain mail or steel plate in particular is what I'm on a quest to gather information about now. What kind of metal would have been used historically? Obviously stainless steel didn't really... exist... at the time, so what kind of steel would have been used? How would you have prevented rust on your enormous coat of metal rings without something like stainless steel?

