Go get a can of canned cold, used for electrical circuits. Heat it, then blast it with cold. It may shrink it.

When I worked at a power plant, a 1 1/2" main steam control valve mounting stud broke. Day shift got a 1/2" hole through it, afternoons got it to 1". We on midnights heated it with several rosebud torches, then hit it with the canned cold. It went clink and we cleaned up the rest with a hammer and chisel and then ran a tap through it.