Rust remover?

There is an acid I used when I had my pressure washing company. It's not sold to the public and it works great! Rust is gone in just a few minutes!
But you can't get any on you cause it can kill you. It will also eat chrome off the metal and make glass look like it was in the ocean for a long time. It turns polished aluminium white.

If you have an arc welder electrolysis works well.

Most of the rust dissolvers take awhile to work.