AEB-L Heat Treat Problem?

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Portman30-06

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Oct 18, 2013
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Hey guys, I was "attempting" to heat treat a few AEB-L knives today. Followed the standard recipe I found on a few sites.

1. Preheat to 1560F and equalize.
2. Ramp to 1940F. Then increased to 1975F and held it there for 15 min.
3. Quenched in canola oil a little over 100F.
This was done in a kiln and without foil btw.

I then washed off the oil and tested it with a file. The file was cutting the steel but not quite as easy as the bar stock. I did some 80CrV2 earlier and the file was skating on it. Is there something wrong with the recipe I used? I tried a plate quench first and it didn't harden so I used the oil. Not sure if that matters. Any help is welcome.
 
My guess is that your file isn't biting because of decarb.
I use 1560 then 1950 for 10-15 min. with a plate quench and after first temper they reliably come out at 62 hrc.
You need ss foil wrap and either a dry ice bath or liquid Nitrogen for this steel.
 
leifjl said:
My guess is that your file isn't biting because of decarb.
I use 1560 then 1950 for 10-15 min. with a plate quench and after first temper they reliably come out at 62 hrc.
You need ss foil wrap and either a dry ice bath or liquid Nitrogen for this steel.
Click to expand...

I agree
 
Yes I have read the AKS recipe and I believe it was a "fail". I then did some more research and didn't find much change in procedure. I have tried this on steel from AKS and Aldo.
 
AEB needs subzero quench and protection from decarb- If you have some foil, just try two pieces, one with and one without and you'll see.
15 minutes @ 2k f. is brutal on any steel...
The canola quench works very well for me when I use it, but I quench in the foil, since AEB likes a pretty fast chill.
 
From what I've read, it does not need a cryo to harden. The cryo only aids in edge retention. It should have somewhat hardened. I did do it a few times. Unclear as the whether that matters. It should just be a "simple" 1940 for 5-10 minutes and quench right? I'm not trying to make this sound simple, but I shouldnt need a grocery list to harden this steel.
 
But I thought you were asking how come that didn't work for you and two people gave you the same answer very different than you said was supposed to work. Why not try their and see what happens? I get mine done by a specialist and he does as they reported. It can be great steal for knives.
Frank
 
The two that provided a valuable reply gave contradicting answers... One said a longer soak and the other said that would damage it. One said oil and the other said plate quench.

What I've gotten from this thread is that I have to use foil. This doesn't explain why it didn't harden.
 
OK, I will try and make it easy:
1) ALL stainless steel knife blades during HT MUST be wrapped in a sealed foil packet.
2) For most stainless steel knife blades, plate quenching is preferred. Oil quench will work, but the plates are just as good, don't require removing the blades, and prevent warp.
3) Cryo benefits AEB-L. It finishes the Mf and gains about 2-3 Rockwell points. AEB-L must reach -95°F to finish the hardening process.
 
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Thanks Stacy. That makes sense, but can I ask what the foil wrap does during the process? And did you mean 95F or -95F?
 
The atmosphere in the oven or forge damages the surface layer of the steel. The foil wrap protects the steel from the atmosphere in the oven or forge. Without the foil wrap, the file is biting into the damaged layer. Grind off the damaged layer and you should have good steel underneath. The foil wrap saves steel and saves grinding.
 
Wrap it in foil, plate quench, and cryo,-or at least subzero by that I mean dry
ice and alcohol. Problem solved.
Ken.
 
what happened in your heat treat was you didn't protect it from decarb. When a steel is hardened in an environment where oxygen gets to it, the carbon migrates out of the steel itself near the surface and forms scale that must be removed. That is why your file bit into it. The carbon was taken out. Must use foil on stainless to prevent that or use salt pots or argon purge etc. the sub zero is needed to get max hardness. not a MUST but a must if you want the performance that aebl brings to the table.
 
samuraistuart said:
what happened in your heat treat was you didn't protect it from decarb. When a steel is hardened in an environment where oxygen gets to it, the carbon migrates out of the steel itself near the surface and forms scale that must be removed. That is why your file bit into it. The carbon was taken out. Must use foil on stainless to prevent that or use salt pots or argon purge etc. the sub zero is needed to get max hardness. not a MUST but a must if you want the performance that aebl brings to the table.
Click to expand...

Thank you. That was more the answer I was looking for. From the reading I did and by ear all I thought the foil did was protect it from scale and discoloration. So from your post I'm going to guess this steel is ruined and add it to the shame pile.
 
kc custom said:
Wrap it in foil, plate quench, and cryo,-or at least subzero by that I mean dry
ice and alcohol. Problem solved.
Ken.
Click to expand...

Ken, not trying to be a smart ass here, but why do you feel the need to add acetone to the dry ice for sub-zero quench? Everyone does it, but there's no reason the dry ice has to be a liquid, and it adds cost to the process.. Potentially longevity to the dry ice is diminished also, but I'm guessing here.


Regardless, simply crush dry ice in cooler, submerge blades. They'll equalize to the same temperature regardless. FWIW I do this with AEB-L and reach maximum potential hardness as verified by hardness tester.

I think we just assume, since you typically plate quench or quench in a liquid medium for austenizing that it's mandatory for a quenchant to be liquid, but in this case, speed to sub zero temp is irrelevant. Yes a liquid will bring the piece to temp faster, but in this case it's unnecessary.
 
javand said:
Ken, not trying to be a smart ass here, but why do you feel the need to add acetone to the dry ice for sub-zero quench? Everyone does it, but there's no reason the dry ice has to be a liquid, and it adds cost to the process.. Potentially longevity to the dry ice is diminished also, but I'm guessing here.


Regardless, simply crush dry ice in cooler, submerge blades. They'll equalize to the same temperature regardless. FWIW I do this with AEB-L and reach maximum potential hardness as verified by hardness tester.

I think we just assume, since you typically plate quench or quench in a liquid medium for austenizing that it's mandatory for a quenchant to be liquid, but in this case, speed to sub zero temp is irrelevant. Yes a liquid will bring the piece to temp faster, but in this case it's unnecessary.
Click to expand...

I actually did'nt use a liquid at first. Once I got my hands on Bob T's book on tactical folders I started to. So here 15 years down
the road its usually LN and a check with my hardness tester for me
Ken.
 
kc custom said:
I actually did'nt use a liquid at first. Once I got my hands on Bob T's book on tactical folders I started to. So here 15 years down
the road its usually LN and a check with my hardness tester for me
Ken.
Click to expand...

Sorry Ken I wasn't trying/shouldn't have called you (in particular) out on this, it's just something I've wondered about when I hear it mentioned, and decided to pontificate after your post.


I do the same as you, regardless. Simply from a practicality standpoint. All that matters in the end is the results.
 
javand said:
Ken, not trying to be a smart ass here, but why do you feel the need to add acetone to the dry ice for sub-zero quench? Everyone does it, but there's no reason the dry ice has to be a liquid, and it adds cost to the process.. Potentially longevity to the dry ice is diminished also, but I'm guessing here.


Regardless, simply crush dry ice in cooler, submerge blades. They'll equalize to the same temperature regardless. FWIW I do this with AEB-L and reach maximum potential hardness as verified by hardness tester.

I think we just assume, since you typically plate quench or quench in a liquid medium for austenizing that it's mandatory for a quenchant to be liquid, but in this case, speed to sub zero temp is irrelevant. Yes a liquid will bring the piece to temp faster, but in this case it's unnecessary.
Click to expand...

Actually, you are partially wrong. The dry ice is never in contact with the blade because there is a layer of CO2 gas between the two caused by sublimation. Gas is a poor conduit for heat. Using a liquid allows the liquid to transfer the heat much more efficiently. Denatured alcohol is a better liquid than acetone.
 
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