Cryogenic quenching question

Guindesigns

Guindesigns

Well-Known Member
I have some D2 I am trying to get ready to heat treatment, and was wondering a few things
Do I need to cryogenic quench?
And if so what's better liquid nitrogen or dry ice and kerosene? Does it matter??
 
I might be starting a brush fire here.... but when it comes to cryo and steel, I can't wrap my head around why anyone would even consider dry ice mixtures.
Why? Because, in order to achieve any positive effects when conducting cryo operations on steel, those START at -240F to -250F, give or take a few degrees.... the coldest you're going to achieve with a dry ice mixture is around -110F, again, give or take based on what it's mixed with. Keeping that starting point of -240F in mind, that pretty much leaves you with Liquid Nitrogen at -345F (+/- a few degrees) to achieve any positive results with your knife blades.

In the past, I've tested "cryo" operations with both LN (Liquid Nitrogen) and various mixtures of dry ice/acetone, dry ice/alcohol, and dry ice/ethylene glycol. When tested, steel samples showed no measurable changes with any of the dry ice mixtures, but in comparison, "significant" changes occurred with steel treated in LN.
Setting up for LN isn't cheap either.....but it does work. You'd need a "dewar", which is nothing more then a large, very expensive thermos bottle, usually used in the artificial insemination industry (cattle, horse, etc). Then you need a source of LN. I'm lucky in that I have a welding gas supply store just a few miles away that sells LN. Even then, the LN will not last long, so if you're going to do it, you have to factor in buy LN every few weeks or so, depending on how well insulated your supply dewar may be.

Before anyone wants to start an argument, I'm not interested in doing that. I'm just putting out information, and trying to save people a lot of wasted time and money trying to use dry ice mixtures. If you're using dry ice mixtures and feel it works for you.... good for you. Take the information for what's it's worth to you.
 
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EdCaffreyMS said:
I might be starting a brush fire here.... but when it comes to cryo and steel, I can't wrap my head around why anyone would even consider dry ice mixtures.
Why? Because, in order to achieve any positive effects when conducting cryo operations on steel, those START at -240F to -250F, give or take a few degrees.... the coldest you're going to achieve with a dry ice mixture is around -110F, again, give or take based on what it's mixed with. Keeping that starting point of -240F in mind, that pretty much leaves you with Liquid Nitrogen at -345F (+/- a few degrees) to achieve any positive results with your knife blades.

In the past, I've tested "cryo" operations with both LN (Liquid Nitrogen) and various mixtures of dry ice/acetone, dry ice/alcohol, and dry ice/ethylene glycol. When tested, steel samples showed no measurable changes with any of the dry ice mixtures, but in comparison, "significant" changes occurred with steel treated in LN.
Setting up for LN isn't cheap either.....but it does work. You'd need a "dewar", which is nothing more then a large, very expensive thermos bottle, usually used in the artificial insemination industry (cattle, horse, etc). Then you need a source of LN. I'm lucky in that I have a welding gas supply store just a few miles away that sells LN. Even then, the LN will not last long, so if you're going to do it, you have to factor in buy LN every few weeks or so, depending on how well insulated your supply dewar may be.

Before anyone wants to start an argument, I'm not interested in doing that. I'm just putting out information, and trying to save people a lot of wasted time and money trying to use dry ice mixtures. If you're using dry ice mixtures and feel it works for you.... good for you. Take the information for what's it's worth to you.
Click to expand...
Where is a good place to buy a dewar and how big of one is usually needed.
 
In general I'd have to second what Rick said. However, much depends on what part of the country you live.... Me, living in cattle country (Montana), dewars are fairly easy to come by, but still expensive. I purchased mine second hand, 20+ years ago. It holds 52lbs of LN (approx 6 gallons). The problem is finding a dewar with a neck size large enough for your uses...... mine is 2 1/2", which is as large as I could find at the time. Most come with neck openings of less then 2"..... which means nothing larger then about 1 3/4" will fit down the neck unless its a dead straight piece of steel..... then of course you could probably make a 1 15/16" wide fit :)

I took the time to look up "dewar" on Amazon..... get it there!! Impressive selection, and many of those prices are better then what I see around here on second hand ones! The only other thing you need to check before diving in...... the local availability and price of LN. I've found the prices vary widely..... in fact, I have two welding places locally that sell it...... one in 4x per pound (that's how the measure LN) more then the other! ;)
 
Sorry if this is off topic, but does D2 need a plate "quench"? I am looking at making some knives in D2 soon, so this conversation is helpful.
 
I have a semen collection and school about 40 miles away. I pick up my son's semen tank with his semen an imbryos and take it when I go to make sure it is worth the time. REI has about 8 500 gallons tanks in the office where they freeze and store semen for the farmers.I take the tanks in and they immediately start filling them. They have an old style scale they set the tank on to read it starting then fill and weight finished. I cringe almost every time watching a young lady with what looks like a heavy duty plastic pitcher dipping into a tank of nitrogen then filling my tanks. They charge $1.35 a pound for the nitrogen. Side good is I have sold 3 knives to the girls in the office for their husbands presents.
 
As far as cryo treating various types of steel, here is a link to the first of three articles written by Larrin Thomas on this subject:
Everything I have read by Larrin is backed up by solid research.
knifesteelnerds.com

Cryogenic Processing of Steel Part 1 - Maximizing Hardness - Knife Steel Nerds

What happens during cryogenic processing of steel? How does it lead to increased hardness? How does retained austenite play into this?
knifesteelnerds.com knifesteelnerds.com

As most of us know, he has many other excellent articles on his site.
 
I use Ln2. I have used dry ice and RV antifreeze and got on the average 1/2 Rc less increase vs Ln2 increase average of 1.5-2 points. Larrin Thomas (recommended on patreon) shows even putting a blade in a freezer makes a difference. The conversion of retained austinite happens on its own without cryo but much slower. Like years slower.
 
Also keep in mind that different steels have different requirements. AEBL only needs to get to -95f. Dry ice slurry does just fine. And as Boss just said, putting the blades in the freezer will get you beneficial results. I have also done AEBL blades without any cryo. I doubt many people would ever be able to tell the difference in actual use between a blade that had been cryo'd and an identical one that hasn't, and that would take a couple of years of use and sharpening to figure out that one was holding an edge slightly better than the other. As knifemakers we obsess over minutiae, as we should. We need to remember that not every knife is intended to push the envelope of what is possible with a knife. I'm not saying to cut corners. I'm saying that unless you do every step under laboratory conditions, the end result is going to be an average of the variance of every step of the process.
 
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I cant seem to find how lone or cold I should allow my D2 to get in LN anyone got any advice on it. I've looked it up on the knife steel reference also from the company itself and still nothing. It all says it will benefit from it but other than that nothing.
 
It depends on the alloy. For simple stainless steel’s like AEB-L, dry ice is sufficient if you were just looking to finish the quench, which is the major thing that cold ttreatments do. With the more complex alloys, that’s not cold enough. I got the info on that from the B-U Rep at the blade show a number of years ago. They had their heat treatment charts for Elmax at the display and I mentioned that it looked like you needed to quench that steel down to about 20° cooler than dry ice. He said that was correct
The trick with D2is getting those carbides smaller. I have heard over the years that Bob Dozier nailed that heat treatment, but unlike some other steals like AEB-L and 52 100, the information was not spread far and wide. Don’t know if it’s still the case or not
 
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Guindesigns said:
I cant seem to find how lone or cold I should allow my D2 to get in LN anyone got any advice on it. I've looked it up on the knife steel reference also from the company itself and still nothing. It all says it will benefit from it but other than that nothing.
Click to expand...

Here's the thing. Published data is typically intended for industrial applications, not knife making. The only ways to find good information is to scour forums and learn from the testing that others have done (and take that with grain of salt) and the second way is to test it yourself. Make little coupons the same thickness as the knives you intend to make. Try a few different recipes. Break them, study them, test whatever trait it is that you are trying to get. Then make a couple of blades and test them the way the knife is intended to be used, because at the end of the day that is ALL that matters.
 
John Wilson said:
Here's the thing. Published data is typically intended for industrial applications, not knife making. The only ways to find good information is to scour forums and learn from the testing that others have done (and take that with grain of salt) and the second way is to test it yourself. Make little coupons the same thickness as the knives you intend to make. Try a few different recipes. Break them, study them, test whatever trait it is that you are trying to get. Then make a couple of blades and test them the way the knife is intended to be used, because at the end of the day that is ALL that matters.
Click to expand...
52100 being a perfect example of your point. Austen is if temps approaching 1550f make for some nice wear resistant carbides which work great for bearings. Not so much for kitchen knives. 1475 works better for that.
 
Although off thread with regards to the steel in question I had a discussed with Uddeholm regarding sub zero.

I was told for example that Elmax must go to a minimum of -100c -196c and be HELD, a simple drop to sub zero wont work to full effect.
With regards to Vanax the sub zero is critical as without the sub zero you will never attain the correct hardness as something like 15% austenite (from memory) is still retained until the sub zero does its magic. Once again this needs holding to be affective.
 
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