I don't have a belt grinder. I'm annealing to make it easier to hand file and sand to 320 grit. Soaking at 1100 to 1200 F helped but it was still pretty hard. If I try this again, I might pack the tube with vermiculite.
I have always had difficulty annealing blades and the 52100 is really difficult. I set a 3" pipe inside the forge and on a low fire can hold it at sub critical heat. I'll try annealing for an hour and see if this helps? Open to any suggestions.