Multiblade Stacked Quenching of AEB-L?

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huntingsgr8

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May 25, 2015
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I've been profiling knives from AEB-L for a few weeks now, and I'm about ready to heat treat them, that said I have a lot of them to do. 24 chef's knives, 14 petty knives, and 14 paring knives. Looking at the cycle times it would take me ages to do these individually, so a thought occurred to me-namely just to stack them on top of each other and do multiple at once. Then I got to thinking that air quenching a stack of blades 1" thick (if I tried to do the petty and paring knives all at once and the chef's knives 12 at a time), might take too long even with compressed air, and that the blades in the center wouldn't harden, or that there would be variable and inconsistent hardening throughout.

Now, I remember reading that AEB-L can be quenched in a slow oil, so I had another idea, what if I stack them, wrap them in foil, bring the stack to temperature, then when I take it out of the oven I put it between two 1/4" steel plates with holes so that I can bolt them together, tighten everything down and put the stack into canola oil? That should eliminate most of the potential for warping, ensure a quick enough quench for more uniform hardening throughout, and save me two days of heat treating.

What are your thoughts and concerns with this idea? Have I overlooked something potentially catastrophic? I wouldn't be so concerned about the time it will take me to harden everything, just that they need to go into the subzero stage of the quench within an hour of the plates and I don't know how long a tub of acetone laden try ice will keep for. Not to mention I have to drive an hour to pick up the dry ice on top of everything too.
 
AEBL tends to warp, even without help.

Within an hour after quench is too long a wait for sub zero. I aim for 5 minutes max.

A relatively rapid quench will improve corrosion resistance and probably edge stability too.

I'd do them one at a time.
 
before I had a dewar and nitrogen, I put the dry ice I purchased into a insulated cooler box, like the styrofoam ones you can get cheap
I pulled the dry ice blocks out as needed over the course of the day as required to make the slurry using denatured alcohol, I wouldn't use acetone

you can stack 3 blades high (of the same profile and pattern shape) for plate quenching and all in one foil pouch. I don't do more than that and each blade isn't more than 2.5 mm thick

I think a stress relieving cycle first helps with warping...but aebl will warp anyway as mentioned and it will warp during grinding.

you are trying to do 52 blades... it's going to take 2-3 days
 
Any reason to avoid acetone for the slurry? The paring knives and petty knives are 1/16" thick. The Chef's are 3/32.
 
Acetone is fine, as is methanol/ethanol (denatured alcohol). The benefit of using alcohol is that most plastic containers will hold it fine while acetone will dissolve many plastics.
 
This makes me think of the time I plate quenched 3 cpm154 blades that were about .200 thick. I did the plate quench separately. I wanted to cool them off a little more before putting them into a cold treatment, so I stacked them together and ran water over them. They were far from red hot, plate quenched, each removed from their own foil. As soon as that water hit the blades the top and bottom blade in the stack warped out. I will definitely not do that again and I would hesitate to attempt doing them as a stack even with clamping them straight.
 
I just did a batch of 30 0.125 thick D2 blades and stacked them 2 per stack, 3 stacks per foil pouch, and 2 pouches per oven heat so 12 blades per run. that helped speed things up a lot and all the blades came out hard, I think a stack of 2 or 3 is fine. I would also get the blades in cryo as fast as possible as already mentioned. like when the first batch comes out of plates and the next batch goes into the plates, the first batch should now go right to cryo, from Larrins work and some other reading minutes make a large difference here.
 
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