On Sun, 25 Sep 2011 19:18:49 -0400, wrote:

Im with you Harold . Never had a set screw harden when heated .

The vast majority of cup end set screws are either A2 or A4 steel -
which is by definition an air hardening steel - and WILL harden when
heated. Just like most exhaust studs. They are hard enough to start
with, but if you heat them trying to get them out they end up as hard
as glass. Very hard to anneal, particularly when jammed into a
casting.

Just checked on annealing A2 steel. You need to heat it to 1575 F and
slow cool in the furnace at a rate of 40 F per hour or less. That's
about 37 HOURS of cool-down.

Heating it in a casting and letting it cool WILL harden it.