Originally Posted by SkyDog75

If iron or steel is exposed to water and air, it'll rust. After removing rust, you need to seal any bare metal away from those elements using paint, wax, grease, or whatever to prevent new rust from forming.

Chrome or zinc plating is often used to prevent rust on bolts or fasteners. If that playing is compromised, the bolt will rust. You can paint or wax the bolts to prevent or slow down rust, or you can replace the bolts with ones that won't rust. (Stainless steel is one option, or you can use bolts with zinc or chrome plating that's intact - not scratched, chipped, or pitted.)