J S Machine
Well-Known Member
I did a test piece at 1900F and drew it at 250F and the hardness did not move. It came out 59/60 Rc and the same after draw.
I just heat treated my first 440C blade, and it came out the same - about59/60 Rc. I don't want to draw it back much further because that's about ideal for the hardness. I have it in draw right now for 30 minutes at 250F. If the Rc doesn't move I'll go to 300F for 30 minutes.
I just want to be able to get it drawn well to be sure it is stress relieved, but not move the Rc.
The crucible chart says tempering at 212F will yield 59Rc, and that tempering at 400F will yield 56Rc. I would imagine 300F would bring the happy medium, but hopefully not below 58Rc.
What have your experiences been?
I just heat treated my first 440C blade, and it came out the same - about59/60 Rc. I don't want to draw it back much further because that's about ideal for the hardness. I have it in draw right now for 30 minutes at 250F. If the Rc doesn't move I'll go to 300F for 30 minutes.
I just want to be able to get it drawn well to be sure it is stress relieved, but not move the Rc.
The crucible chart says tempering at 212F will yield 59Rc, and that tempering at 400F will yield 56Rc. I would imagine 300F would bring the happy medium, but hopefully not below 58Rc.
What have your experiences been?