What you need is a oxy/Acetylene cutting torch,
---------- Post added at 08:32 PM ---------- Previous post was at 08:25 PM ----------
I use to clear all the debris off the bolt with a wire brush,(bolt caught in vice or double done up on a upright tube) then a squirt of wd 40,then get a compressed air ratchet at it, afterwards apply some engine oil hydraulic oil even better not expensive stuff, just dab it into the threads, or buy new bolts