Tesla says it uses proprietary stainless steel (possibly from Outokumpu of Finland, Europe's largest producer, which runs a plant in Calvert, Alabama). However, even proprietary stainless steels can stain, especially if any cheaper steel fittings beneath the Cybertruck's panels react with the stainless product.There are five basic families of "stainless steel": austenitic, ferritic, martensitic, duplex, and precipitation hardened. Some containing chromium among other constituents, such as nickel...