Fillet knife heat treat

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Sep 2, 2017
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4
Hi new to the site.
I am making some of my first knives out of quality metal. I am trying to HT an elmax fillet knife. I followed the directions from where I got the metal. I think it was in the oven for 20mins at 1950°F in 309 foil. Taken out and plate quench between 2 3/4 aluminum plates with compressed air blowing between till room temp less then 5 mins is my guess. Blade was still able to bend with my fingers. Yes bend not flex. Talked to where I got the metal said it should have worked. Talked to UB they said should have worked. Tried a second time same result. Talked UB again they said I could send it in and they can tell me if I got the right metal. Third time 2 knives in ramp up to 1450 hold for 10 mins up to 1850 hold for 5 mins up to 2050 20 mins on one knife different material elmax 20 more mins at temp quench between 3/4 frozen plates compressed air between again still able to bend the blade with fingers again not flexing bending. Handle hardness is low 60's didn't test the blade. Any idea on what I am doing wrong?
 
I have no idea on why it is not working, but I am planning to make some fillet knives out of Elmax so I am eagerly awaiting your answers.
Tim
 
Are you sure about your oven temp? Maybe your tc is bad, or wires switched. You should see the knife orange clearly through the packet when you remove it.
 
I have seen this with AEB-L and CPM 154, UNTIL it is chilled in the dry ice/alcohol. Tested 64 and 63 HRC after the freeze. I'm not sure about Elmax, but maybe...
 
You where fine after your first heat treat. This is quite common till you cryo or temper. This type of steel seams to take a handful of time after quench to get non bendy. I don't know why it does this but it happens to me. After your first quench you should have gone straight to cryo and then temper and I bet you would have had a hard blade. What I'm not sure is the blades condition now after that many quenches. I know with AEB-L thy say DO NOT do more then one quench. What oven do you have?
 
UB told me that I should be fine I will check with them about heat treating again thanks. I will post if it does change as you guys said. Thank you.
 
Kevin McGovern yes it was clearly red threw the envelope after removal from kiln. The other knife was much thicker and red threw envelope also.
 
did the same thing years ago doing my first few blades. right from quench the blades will still have so play to fix warping (in your case you caused warping) next time temper or cryo and then temper i promise that post temper the blade will no long take a bend and set
 
B-U says that Elmax really needs liquid nitrogen to get the best performance. The dry ice Slurpee is not cold enough.
 
I have had steel come out of the oven and after quenched and cold bend like a noodle. Not till it gets its temper would it get stiff. It's weird wish I could reproduce that with every blade. Makes straightening easy lol
 
The Mf on stainless steel is well below room temperature. It has to drop to -100F to convert to martensite. Your blade after 5 minutes and at room temperature was mostly austenite ... which is like rubber. Once you cool it with a dry ice slurry or LN it will get hard.
 
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This is correct. The blade that was heat treated multiple times didn't harden at all. Guessing that has something to do with the fact it was heated so many times.
 
I doubt it. Send it to me and I'll heat treat it.

Austenitize
Quench
Cryo
Temper

And it will be hard and springy.
 
Weird thing I see with AEB-L is after quench it will skate a file and I can still bents it really easily for quite awhile after the quench. Not till I temper it with it loose that bendyness
 
JT, do you mean with AEB-L it will stay bendy after quench for a couple hrs as long as it's before quench? I've HT'd AEB-L and a couple of Sandvik's steels which are also bendy right out of quench (aluminum plates), but I was thinking (always painful for me) the bendy stage was only for a few minutes, until the steel reached room temp, or very few minutes after that. If it will stay bendy until put in freeze stage that would sure give plenty of time to straighten any warps.

Ken H>
 
Mine stays bendy for a long time. I leave in the quench plates till cold and then pull it out after 3-5 min and straighten it. I can do it with ungloved hands. It's the only thing that makes AEB-L usable. But then agian I have settled on a really good process for AEB that has them coming out laser straight. Let me see if I can post a pic.

Right after I open the plates. Not using foil has helped a ton.
Photo%20Sep%2026%2C%207%2026%2009%20PM.jpg


Here it is with a scale (machinists ruler) laid across the length of the blade from point to tang.
Photo%20Sep%2026%2C%207%2044%2001%20PM.jpg
 
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