If you clean them with muriatic acid (hydrochloric acid solution), they will clean up fast and look great for 10 minutes, and then they will start to rust faster than anything you have ever seen. Any piece of steel in the same room will start to rust too. If you do use muriatic, be sure to wash the metal very thoroughly after and dry it very quickly. Oil it well too. I'll bet it starts to rust before you can get the oil spread around.
Something a little tamer and not so prone to rust is phosphoric acid used to clean driveways and bricks. It is the main component in Naval Jelly. It is a fairly strong acid too, so wear gloves and eye protection.