your chains may be too big for this trick
I have had good luck getting rusted items apart by soaking them in:
50/50 percent solution of acetone and Automatic transmission fluid.
but, you would need a container that had a sealable top (5 gal bucket) as the acetone will evaporate off in time.
also this solution is very flammable!!!!
it will work in time on some of those things that just, must come apart and you can not put heat on them.
as others have said: soaking them in oil, maybe with a little graphite added for extra measure.