So I'm not metallurgist but my impression is that stainless steel is used as an example because it's readily available, relatively cheap to produce and sufficie

So I'm not metallurgist but my impression is that stainless steel is used as an example because it's readily available, relatively cheap to produce and sufficiently effective. A number of megastructures require much greater tensile strength than that (eg space elevator). Sometimes those materials are theoretical, sometimes not and even when not, often we've yet to produce them in sufficient quantities for such a large engineering effrot. But stainless steel cylinders? There's no in our technology to produce those (although producing them in space or on an airless world like the Moon or Mercury might be a challenge given our reliance on oxygen refining steel). I don't know if there are any issues with having different alloys (eg carbon steel and stainless steel) in contact with each other. I know with other metals this can be an issue. But again, I'm no expert.