They normally use a rattle gun, and the nut is an alloy and the shaft a steel (had to cut one off a couple of weeks ago for my brother, and there were no sparks from the nut, and plenty from the shaft).
When the rattle on dissimilar metals, they heat up and fuse together. I can't work out why they don't put a flat on the flange of the ball to allow a big shifter to be used to stop the ball from rotating whilst undoing the nut.
Cheers
whitedg