Dogface,
Don't anneal the plate, just stress relieve it. In anneal you heat the metal to above the transition temperature and allow to slow cool, usually bright orange hot. This oftens brings a risk of damage to the metal grain structure and warping. To stress relieve, just heat to above the temper color blue, like where the metal turns grey, or at most to a very dull red in a dark room and allow to slow cool. Now the metal is soft enough to cut, drill & tap, but it does not risk the warp as you get with a full anneal. I try to avoid heating any steel to above the transition temperature, orange hot - 1500F - where a magnet will no longer stick to iron, for any shaping, bending, forging. I only get the metal orange hot for the final hardening step for springs, frizzens, and case hardened parts, and then only for a short period of time only.
I hope this helps,
Jim
From Wakiso, Uganda
