The traditional methods of rust removal for big jobs are sand blasting, soda blasting, and the commercial Redi-Strip process where you can do complete car bodies and frames. Our local club has a portable sand baster and a soda blaster in the Tool Lending Program for use by club members. For smaller parts that may fit in a bucket there are some do-it-yourself processes.

Vinegar bath:
Take the offending parts and dump them in a glass or plastic jar filled with vinegar (white vinegar works fine). Let them sit for a couple of days and then pull them out and clean them using a fine wire wheel. If all the corrosion is not removed, put them back in the vinegar for another couple of days. Wire wheel them again and your hardware will emerge clean and shiny. Of course, rust pits will not disappear, but the rust will be gone. You can use steel wool or a wire brush if a wire wheel is too awkward. This method is non-toxic and inexpensive.

Chemical and Electrical:
There some commercial chemical brews that are cheap enough and generally non-toxic. You can check out Evapo-Rust. A friend has been using Evapo-Rust with very good results. Also see electrolysis rust removal. Spic-n-span is a good substitute for "washing soda". It's also sodium carbonate based (not sodium bicarbonate). I have used the electrolysis process with a plastic bucket and battery charger. It works if you walk away and leave it alone long enough.

Molasses:
On 8/8/2023, Mark Wellard in Australia wrote:
"I've been using molasses to successfully remove heavy rust on parts. It takes a while, sometimes a couple of months, but it is much cheaper than Evapo-Rust if you have the patience. --- One drawback that I've found this week is that it eats alloy parts. I left my front shock absorbers soaking for a month to clean up the arms but the surface of the bodies has gone chalky. It might be worth flagging the risk of damaging non-ferrous material".

On 13 Aug 2023, Mark Wellard in Australia wrote:
"Evapo-Rust is an excellent product that is very expensive if you have a significant volume of parts to recover. I would prefer to use it but a tub of molasses works the same way. It chelates the rust, rather than eating the material like an acid. Coca Cola contains phosphoric acid and falls into this category.
An example of how molasses was beneficial was my twin cam block. The pistons had been rusted in place for god knows how long. The machine shop bored it to 20 thou over after breaking the pistons out. It looked good, but the next day there were rings of rust in the bores where the rings had been. They bored it to 0.040” over and the same thing happened. They gave it back with instructions to soak it in molasses for a couple of months. After that, another bore to 0.060” oversize resulted in clean bores. Maybe they would have been OK anyway, but the machinist was pretty confident it would need sleeving.
I’ve had great success with numerous parts since then and it’s a common approach when you search the web. I wasn’t aware until now about its impact on alloy and thought a "beware" might be in order".