Caldera

I appreciate the responses, they were all helpful. The blade was being supported on a metal dog cage in a garage. Will not make that mistake again. There was some hammering below red after a couple of heats. I may have done it on the last heat just to straighten it a little bit before I called it finished. .

This past weekend I made my first attempt making a knife using O-1 tool steel. I started out with flat stock and using a Whisper Momma propane forge got it into the shape I wanted. I was not ready to oil quench it quite yet, so I let the blade air cool. After 30-45 minutes, it was cool enough for me to handle and, wanting to see how it looked cleaned up a bit, started to clean it with an angle grinder with a wire brush attachment. I had the tang of the knife in an vise and was applying some pressure when the knife snapped. Before doing anything work to the steel upon finishing, should I have tempered it? Besides breaking it, is there something I should have done? A friend of mine made a blade at the same time and is worried to do anything else to it. Any thoughts?