well i heard all kinds of talk the tank wouldn't be that rusted Blah Blah Blah not sure who mostly from RCU it would take years for it to rust Blah Blah Blah

well i took this piece of steal square tubing grinded the paint of left it outside for 2 weeks
not everyday was a rainy day but just 2 weeks outdoors and the results are rust  

so if a tank got a chip or scratched or a dent that took the paint off to the metal i think it would rust there for i will put rust i thank you ...lol

I hear you  It might be 2 or 3 inches thick  but the surface would still rust  like a new 1984 Chrysler  Duster

them K-Cars rusted pretty good...lol

Absolutely true. I gave up arguing over there. WW II tanks were not designed to last long and not a great deal was put into priming and paint. Along edges, around bolts, in shallow points, it would not take much to start to rust. Hell I remember in 1979-80 we got our new Grizzles right from the plant in London with 3KM on them. We took them to Northern Quebec for 6 weeks, then off to Norway for a month by the time we got home we had that light surface rust around the things described above plus a couple of deep gouges in spots (not my fault, I was just the RO).
I remember this because we had a dress parade for some civy Government official so we had to have then spiffed up and that required us doing touch ups...