Heat Treating Steel Weapon Teeth Here's the stages of a set of S7 tool steel teeth for Cavalier as I took them through a heat treatment. They were cut and countersunk raw at a Brinell hardness of 197, brought up to 1250°F in an Olympic Kiln and held for a half hour, and then brought up to 1545°F, held for a half hour, and the kiln faulted out before it could ramp up to the recommended 1750°F for hardening S7. No matter, after the steel air cooled with a fan to 150°F, they were thrown in the oven for an hour at 300°F, which tempered them nicely. The hardness is floating around 480 Brinell/50 Rockwell, which definitely lower than the 555 Brinell/55 Rockwell hardness I was aiming for, but is such a vast improvement over raw S7 that I'm still considering my first attempt at heat treating steel a success!