It's stamped steel. You can see the spot welds, and where the metal is rolled, and the rust. Not pot metal. I'm guessing it's nickel plated. Peel some of the plating off and observe if it is magnetic, nickel is. Chrome plating will also be, but only because chrome uses nickel as a base plate. 99% chance it's nickel plating. Chrome was expensive and uncommon at the time, whereas most steel parts that had to be pretty were nickeled. Nickel also oxidizes and dulls, and looks exactly like that. Chrome pretty much doesn't dull over time.