Cryo Treatment Of AEB-L

Randy Lucius

Randy Lucius

Well-Known Member
I'm going to be doing more knives in AEB-L and have some questions about cryo. Since I won't be producing a large amount of blades would a LN tank be a waste of money? How long does it last in the tank? Would dry ice Acetone/Alcohol be more cost effective? This is the tank I'm Looking at. Thanks!!
Ln Tank.JPG
 
Randy, here's a thread where I purchased 10 liter dewar and much is discussed there. How long will LN last in the dewar? All depends, I think I've still got enough LN to treat a few more blades and it's been a tad over 8 wks now since filling. Which is most cost effective? "IF" you factor in the $200 (plus taxes) for the dewar and you only do a few blades, dry ice slurry. Also depends on cost of LN in your area. That you'll have to check around, as I said my local cost varied from 50 cents/liter to $6/liter depending where I got it. Usually LN is available at a welding supply house.

Also depends on cost of dry ice in your area. https://knifedogs.com/threads/ln-dewar.51471/
 
KenH said:
Randy, here's a thread where I purchased 10 liter dewar and much is discussed there. How long will LN last in the dewar? All depends, I think I've still got enough LN to treat a few more blades and it's been a tad over 8 wks now since filling. Which is most cost effective? "IF" you factor in the $200 (plus taxes) for the dewar and you only do a few blades, dry ice slurry. Also depends on cost of LN in your area. That you'll have to check around, as I said my local cost varied from 50 cents/liter to $6/liter depending where I got it. Usually LN is available at a welding supply house.

Also depends on cost of dry ice in your area. https://knifedogs.com/threads/ln-dewar.51471/
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Thanks Ken! I'll check out the other thread.
 
Randy - The size of the tank makes a difference. When I looked, it ranged from a couple of liters up to hundreds of liters. More important was the size of the opening. Most of the dewars had an opening less that 2 inches. It was hard to locate one with a bigger sized neck opening.
 
Dennis Morland said:
Randy - The size of the tank makes a difference. When I looked, it ranged from a couple of liters up to hundreds of liters. More important was the size of the opening. Most of the dewars had an opening less that 2 inches. It was hard to locate one with a bigger sized neck opening.
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The one I'm looking at in the picture above is about 5 gallons with a 4 inch neck.
 
Randy Lucius said:
The one I'm looking at in the picture above is about 5 gallons with a 4 inch neck.
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5 gallon? That's what, 20 liters, roughly anyway. 20 liters will hold longer than my 10 liter, but the 4" opening will hurt some on holding time. The 50mm opening will take what's called a 2" wide blade, well, it'll like .040" or so. Only if you plan to do a lot of wider blades would I consider the 4" opening, unless of course you're getting a really good price on it.

If you decided to look at a used dewar, be sure the vacuum is intact and it's really hard to tell until you fill with LN and see how long it holds.

Have you checked price of LN around Tupelo area? I'd be interested to see the price range of where I've called "home" a large part of my life.
 
This is the tank dimensions. Running the calculator on it says 4.67 gallons, 17.67 liters filled to 19 inches. Local price per liter is $2.50 so around $45 to fill.
Ln Tank 2.JPG
 
So I don't know much about dewars, but that is maybe 1/4 of the capacity of the shell. It's like an old coffee thermos with a pretty big outside shell and not a very big inside.
 
tkroenlein said:
So I don't know much about dewars, but that is maybe 1/4 of the capacity of the shell. It's like an old coffee thermos with a pretty big outside shell and not a very big inside.
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You’re right. After looking at the ad closer it only holds 3 liters. I want one with a capacity of at least 10 liters.
 
I have been playing with heat treating AEB-L. I bought -100 degree camper antifreeze $25.67, I bought a 7lb block of Dry Ice from Publix for $12.71, I can get the dry ice any day of the week. I never priced LN here in my area. I figure if I am going to do a batch of AEB-L knives I will send them out to be done.
 
Benjy said:
I have been playing with heat treating AEB-L. I bought -100 degree camper antifreeze $25.67, I bought a 7lb block of Dry Ice from Publix for $12.71, I can get the dry ice any day of the week. I never priced LN here in my area. I figure if I am going to do a batch of AEB-L knives I will send them out to be done.
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Send `em to Randy.
 
BTW according to my thermo-coupler the antifreeze dry ice went down to -84. I was looking for alcohol but had no luck finding any when I was out.....
 
I have some thoughts about the economy of LN and throwing out a pretty good chunk of change for a dewar, because I've been thinking about it. This would be pretty dependent on a couple of things, one being how much and how easy LN is to get in your area. Another would be your "business model," whether you do a lot of one off customs to order, or if you build specific patterns when and if you want.

Personally, I do a lot less to order and more of what I want. I think that a lower volume guy like most of us could get by with a couple fills a year, and do our heat treating in batches and have profiled, hardened blanks ready to grind and finish when it was time to do so.
 
tkroenlein said:
I think that a lower volume guy like most of us could get by with a couple fills a year, and do our heat treating in batches and have profiled, hardened blanks ready to grind and finish when it was time to do so.
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That’s kinda what I’m thinking too Todd. Do a batch of 10-15 blades ready to grind whenever I need one. The next question is what is the real benefit of cryo on AEB-L? Is it worth the extra effort?
 
Randy Lucius said:
That’s kinda what I’m thinking too Todd. Do a batch of 10-15 blades ready to grind whenever I need one. The next question is what is the real benefit of cryo on AEB-L? Is it worth the extra effort?
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I started to say yes that cryo treatment is worth the extra effort, but then I started to read Cryogenic Processing of Steel on KnifeSteelNerds.com.
I think it might be worth a read and form your own opinion from that..

It's possible that antifreeze and dry-ice might meet your needs, or not. I found the article quite interesting if a little heavy going in spots.
 
Larrin's 3 articles on cryo treatment is well worth reading, and all 3 articles need to be read. My take on reading them was..... you can find a study to support most any claim you make about most anything. Larrin does a good job of gathering many different studies together, and does some tests himself. Also, from reading the articles it seems that different steels react to cryo differently, so a series of tests needs to be done on many different steels.
 
KenH said:
Larrin's 3 articles on cryo treatment is well worth reading, and all 3 articles need to be read. My take on reading them was..... you can find a study to support most any claim you make about most anything. Larrin does a good job of gathering many different studies together, and does some tests himself. Also, from reading the articles it seems that different steels react to cryo differently, so a series of tests needs to be done on many different steels.
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That's the impression I got. You summed it up better than I did. Thanks
 
Sean, thank you for nice words.

Since I work mostly with AEB-L I feel cryo is worthwhile for AEB-L, if for no other reason is the extra hardness. With just -5F freeze after quench I seldom get much over 61, "maybe" 62 Rc out of freezer. After tempering I normally have a 60 Rc blade. That works good, but everybody says AEB-L starts to really shine for kitchen knives at 62 Rc. I normally have (only a few blades as of now) about 64 Rc out of LN, then after tempering at 375F to 400F temper I've got a solid 62 Rc.

As ya'll know I've only had the LN a short time (9 weeks) and have only a couple blades in my (wife's) kitchen in the 62 Rc range. Right now they're working really good, but so does the 60Rc blades {g}

From reading Larrin's articles I really suspect what holds for D2, or L6, might not hold for AEB-L, or other alloys. To really know what cryo does for each alloy, each alloy would need testing for cryo vs -5F vs room temp. Most folks say the -95F dry ice/alcohol slurry is same as LN. Not sure, but I do think I get better from LN, but maybe that's just wanting to justify the purchase of the dewar?

Randy, I do agree you want at least a 10 liter dewar.

Later
 
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