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J S Machine
06-16-2010, 07:17 AM
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?

Cliff Fendley
06-16-2010, 07:41 AM
Who said that's the ideal hardness for 440C? In my opinion and experience 440C performs best around 56-57.

Cliff Fendley
06-16-2010, 07:44 AM
You also need to draw it for about 2 hours.

30 minutes at 1850 then 400 for 2 hours you should be about where it's going to work best.

J S Machine
06-16-2010, 08:46 AM
Who said that's the ideal hardness for 440C? In my opinion and experience 440C performs best around 56-57.

Ok. I just said ideal hardness because I like good edge retention. It's been my experience that the softer it is the worse the edge retention. Others with more experience will know more, so I'll take the advice. It did not move at 250F and it is cooling from being drawn at 300F right now. As soon as it cools I'll check it and then probably shoot for 400 for 2 hours. I figured it probably needed a longer stay in draw for good stress relief.

Thanks.

H.L. Holbrook
06-18-2010, 08:46 PM
:) What Mr. Fendley said. I've used that same treatment for several years. Pretty much the standard for 440C.

Jerry Bond
08-23-2010, 05:06 AM
Cliff, Do you draw @ 400 for 2 hrs once or twice? I draw 2 hrs twice, Don't have an RC tester, maybe I'm messing up and don't know it. I think that 57-58 rc would be just right. Jerry

Cliff Fendley
08-31-2010, 06:38 AM
Sorry Jerry I just saw this. I haven't seen that it matters. Once or twice gets the same RC and can't tell the difference on how they perform.

Jerry Bond
09-02-2010, 07:09 PM
Thanks Cliff, that eases my mind. Jerry