Anyone do the AEB-L Double Quench?

Self Made Knives

Well-Known Member
#1
I've done a few AEBL blades and only did the 1975 degree single quench. But, I was reading some stuff Devin Thomas put out a few years ago and he was doing a quench at 1725, then reheating to 1975 for a final quench. Anybody here do that? Is it worth it? I've got a couple small hunters to HT this week and was wondering if I should try it.
 

C Craft

Well-Known Member
#3
I am definitely not the one to answer this but, I know who to ask,.................. Kevin R. Cashen ! However if I just had to answer......................I am gonna lean toward XX! However since I have never used any of it, and I decided I needed to know I would definitely hit Kevin up!! Oh by the way his name is a link to him on this forum!!
 

KenH

Well-Known Member
#4
Since Devin T says double quench is a good thing, and helps keeps a smaller grain - I'd say it's a good thing. Devin has done more AEB-L testing than most anybody I've read about. He's the guru for AEB-L for sure.
 

Self Made Knives

Well-Known Member
#5
Since Devin T says double quench is a good thing......
Ken, don't get me wrong, I don't doubt Mr. Thomas' knowledge, or yours either for that matter. Its just that when I look on the forums it seems that nobody else is really talking about a double quench. I don't think very many people do both, so I was just wondering how many of the guys here do a double. Or have even heard of the double. If I remember correctly, I think you were talking with him on that post on bladeforums. Guess I'm wondering if it's one of those splitting hairs things, kind of like the debate of whether a dry ice cryo is as good as nitrogen.

I am working on a youtube video right now and using AEBL for a young man's first knife. I was trying to decide if I should do the double in the video. Well, actually, trying to decide if I should just start doing it every time. Either way, I'm sure the youtube trolls will criticize it, lol.
 

KenH

Well-Known Member
#6
Anthony, I suspect the double quench will improve the HT of an AEB-L blade, but how much you ask? I expect it will be about the same as dry ice vs deep freeze at -5⁰F treatment. Either will make a good blade, I do believe the dry ice is better - that's why I use dry ice. If you took two identical blades, one dry ice and one freezer at -5⁰F treatment, would you be able to tell the different in normal casual use in kitchen? I doubt it - just too many variables involved in casual kitchen use. Would a carefully controlled test show difference? I expect so.

Shucks, AEB-L steel will make a very decent blade with no freeze treatment at all., but each step above does make it a bit better. I'm planning to try Devin's double quench method, just not done it yet.

Ken H>
 

Andre Grobler

Well-Known Member
#7
I have done it, you can get an extra hardness point with it a few blades i got to 64 with a 350f temper without i get to 63 on a 1090 degc aus temp and cryo...... BUT you are heading for warp or crack city... the ones that worked could keep a 7dps edge on my cutting board... the ones that didnt became, well shop hard and sharp bits... it is also possible to not crack and just blow the grain giving you more hardness and brittleness... it requires exoerimentation... for a hunter i wouldnt do that... just the lowest aus temp like 1065- 1070 degc and oil quench and subzero that should give you 62 and a good edge...
 

Self Made Knives

Well-Known Member
#8
[QUOTE="... for a hunter i wouldnt do that... just the lowest aus temp like 1065- 1070 degc and oil quench and subzero that should give you 62 and a good edge...[/QUOTE]
Yeah Andre, that's pretty much what I do now, except I do a plate quench. If there's an increased chance of cracks and warps, you might have just steered me away from it! Don't need that!
 

Andre Grobler

Well-Known Member
#9
I suspect plate quench might reduce the possibility of cracking and warping but then you need subzero... in my opinion... i will now oil quench and then go to plates... when i try it again... but honestly 62+ on a 350f temper performs very well
 

Andre Grobler

Well-Known Member
#10
Also i aim for 63 (no prequench) or 64( with prequench) on short blades with 1090 degc aus temp and LN cryo. But your oven’s variation at those temps make it a bit iffy
 

Self Made Knives

Well-Known Member
#11
Also i aim for 63 (no prequench) or 64( with prequench) on short blades with 1090 degc aus temp and LN cryo. But your oven’s variation at those temps make it a bit iffy
I had to convert C to F, so you're 1090C is a little hotter than what I've been using. I have my Evenheat programmed for 1975F (1079C) and I ususally get 61-63hrc with dry ice/acetone cryo. The first couple times I did AEBL I went up to 1995F (1090C) and it didn't seem to get anymore out of it. Everything I read seemed to imply the 1975F was fine, so that's what I've been using lately.
 

Andre Grobler

Well-Known Member
#14
Well what i THINK it does is gain you a bit less grain qrowth so you. An push it a teeny bit harder, but it can also just make you have smaller grain at your chosen hardness
 
#15
I do the pre-quench. Before I started doing the pre-quench, I would sometimes get a warp during the LN2 soak. I would plate quench, unwrap, water quench to room temp., check for straightness, & the blade would come out of the LN2 with a slight warp. Since I started doing a pre-quench, I haven't had this problem.
It also helps refine the grain which, in theory, makes a better blade which is a win-win. Try it and see what you think. Let me know if you think its worth it. One more thing, in case you don't already know, you can pre-quench & harden in the same foil.
 

Andre Grobler

Well-Known Member
#16
That is interesting... I am quenching in oil and often get significant warp after the hardening quench... and straightening it by hand seemed to give me cracks... i am thinking an interrupted (after 4 seconds) oil quench which then goes to plate quench would be useful... strong smoke not fire in the oil...
How would one calculate the right temps for something like 440c D2 elmax etc? I guess you need to know what the re-crystallisation temp is and go from there, but I do not know how to read steel charts that well...
 

Andre Grobler

Well-Known Member
#18
I am thinking i need to go there... have some 600x150x100mm big long heatsinks bough for a monster amp that may just fit the bill - they have mounting channels unfortunately so not sure about what to do about those channels - could lead to uneven cooling - even if i put some oil or air through it...
 
#19
I do the pre-quench. Before I started doing the pre-quench, I would sometimes get a warp during the LN2 soak. I would plate quench, unwrap, water quench to room temp., check for straightness, & the blade would come out of the LN2 with a slight warp. Since I started doing a pre-quench, I haven't had this problem.
It also helps refine the grain which, in theory, makes a better blade which is a win-win. Try it and see what you think. Let me know if you think its worth it. One more thing, in case you don't already know, you can pre-quench & harden in the same foil.
Darrin...does blade orientation in the LN2 affect what the blades do as far as warp? I can only lower my blades point first (small mouth tank) and have not yet seen any warping...I've done about 70 A2 blades this way.
 
#20
I hang my blades in the LN2 by wires so they have no side pressure on them. When I do get a warp its from stock that is .090" or thinner, is very slight and not hard to correct during tempering. Also, it tends to happen more with 13C26 than AEB-L. The only other alloy I've had a problem with in the LN2 is some .080" A-11 from Zapp. Everything else is fine as long as its straight when it goes into the LN2. I've never had any problems with any thickness of A2 and I use a good bit of it. I love A2 and consider it to be very under-rated. Its easy to H/T, has plenty of toughness, takes a nice edge, & holds it well.
 
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