Are a Lot Of Knifemakers Still Doing Sub-Zero Quench?

redsquid2

redsquid2

Free-Range Cheese Baby
Knifemaker / Craftsman / Service Provider
Joined
Aug 31, 2011
Messages
3,090
I looked into the general question of sub-zero quenching, by doing a custom Google search. What I found was threads that were mostly older. I mean, some of them went back to 2003. I got the impression that "cryo" treatment does not create an improvement that would be noticeable in the real world. I am sure there has been controlled testing, and documentation of changes in the steel, but I am still skeptical of the practicality of this procedure.

I would think cryo treatment would be a fad whose time had passed. Yet I am aware that Texas Knifemakers Supply offers it, and when I recently requested a quote from Peters, cryo was automatically included in the quote.

I don't want to open up a hornets nest, but my opinion is, if it has only been around 10 years or so, people were making perfectly good knives without it. I'm thinking about the knives I have had, since the 1970's, many of which were very good stainless, and I just don't get excited about cryo.

Was there something I missed?
 
Does it improve some steels, IMHO, yes.

Is it necessary to make a good knife...no.

Does it improve all knife steels...debatable.
 
Is it beneficial for simple carbon steel knives? No, I do not believe it is.

Is it beneficial for high alloy stainless steel blades? Yes but the results vary for the different steels.

Make sure to define "cryo", as well..... we are talking temperarures below -105F... usually in the -300F range. A deep freezer won't cut it.
 
Last edited:
If you like things like large amounts of retained austenite in high alloy steels or lower levels of hardness at the same austenizing temperatures, then yeah, you won't get much out of proper cryo.:D But seriously, cryo helps to complete the conversion to martensite in steels that need help and while some of the simple steels that us metal pounders use will transforms completely at room temperature, others steels will not.
 
The quench point on some steels is so low that a sub zero quench can be thought of as "part of" the quench.

It's not hype at all but only some steels benefit from the process.
 
Using different search parameters, I found a couple more useful threads.

Summarizing: 1. 154CM and CPM154 benefit from cryo.
2. "Cryo helps, if the person doing it knows how to incorporate it into the overall heat treat." 3. A guy named Phil Wilson knows how to incorporate it into the overall heat treat.

My experience is I have a 154cm knife that was cryo treated. It probably does better than the old Buck 112 I had, in edge holding. I haven't really abused it enough to know if it is chip-resistant.
 
Last edited:
Don't assume your Buck wasn't Cryogenicly treated. Paul Bos has been Cryo treating their knives for a loooooong time. Google Paul Bos. :-)
 
Yeah, the Buck 110 was mostly like done with cryo. Most heat treaters doing stainless use it. Bos has as long as I've known of him.

It is probably showing up mostly on older threads because this was figured out some time ago and it isn't a particularly exciting topic of conversation anymore. I'd wager that most of us using complex and stainless steels quench to sub zero in order to complete the quench. For example, Mf for D2 is generally given as -100 F. It isn't rocket science and it isn't voodoo. It's just heat treat. And I think that most of us using those steels use it. I wouldn't fool with D2 without sub zero.

That said, I haven't seen much benefit of full cryo. Sub zero = reduced RA. Full cryo= reduced RA and fine eta carbides that don't do anything in a knife blade. Just my opinion.
 
Regardless, if the Buck 114 isn't made from 154CM it is an apples to watermelons comparison.

As stated by some of the others, some steels NEED cryo, some do marginally better with cryo, and some won't benefit one bit from it. And, it must be an integral part of the heat treating regimen. Meaning: the timing, tempering temperatures, etc... EVERYTHING is a part of this whole.

Whoops, Nathan you posted as I was writing. The "regardless" comment was about the OPs post, not yours.
 
Last edited:
Sub-zero quench has been around for a long time , 50+ years , and is -100 F.
Cryo is newer and is -300 F
They are two different things and the more complex the steel the more it benefits by these two treatments.They are part of the HT ,not an add on.
 
I get the impression that the jury is still out on the eta carbides. Suffice to say that they probably do no harm to a knife blade at a minimum.
Nathan the Machinist said:
Yeah, the Buck 110 was mostly like done with cryo. Most heat treaters doing stainless use it. Bos has as long as I've known of him.

It is probably showing up mostly on older threads because this was figured out some time ago and it isn't a particularly exciting topic of conversation anymore. I'd wager that most of us using complex and stainless steels quench to sub zero in order to complete the quench. For example, Mf for D2 is generally given as -100 F. It isn't rocket science and it isn't voodoo. It's just heat treat. And I think that most of us using those steels use it. I wouldn't fool with D2 without sub zero.

That said, I haven't seen much benefit of full cryo. Sub zero = reduced RA. Full cryo= reduced RA and fine eta carbides that don't do anything in a knife blade. Just my opinion.
Click to expand...
 
A few years ago I bought a dewar and and incorporated LN as part of the quench. At that time I had
been using dry ice and alcohol for about 8-10 years. I then tried freezing my quench plates and began
to get blades as white as when I put them in the foil. The answer compared to LN or dry ice- NO.
My take is most makers not using a freeze (dry ice or lower) either don't have access to LN, dry ice,
or don't want to bother with it. The argument about it not helping is a circus either way cause it can't
be proven by any method I know of froze or not. I really don't need to enter these arguments anymore
and no I don't have a laboratory. I have been carrying knives since I could walk. Does it help YES, and I
will continue to use it until I feel I'm using a steel not requiring it. So far I have'nt found that steel.
Ken.
 
kc custom said:
The argument about it not helping is a circus either way cause it can't
be proven by any method I know of froze or not.
Click to expand...
Ken, if you feel it can't be proven either way, I don't understand why you would go through the trouble. You mention something about freezing the quench plates and getting "whiter" steel. Forgive my ignorance... what do you mean by that? Does it polish to a higher degree?

kc custom said:
I really don't need to enter these arguments anymore
and no I don't have a laboratory. I have been carrying knives since I could walk. Does it help YES, and I
will continue to use it until I feel I'm using a steel not requiring it. So far I have'nt found that steel.
Ken.
Click to expand...
Are you using primalrily stainless steel, Ken?
How do you determine it is helping?(finish, performance, destruction testing?) The previous "circus" statement has me a bit confused when reading this last one.

Please don't read this as being argumentative... I am asking a sincere questions.
 
Last edited:
Rick the steel I use is 99% stainless, I should have clarified that. What I'm saying about the circus argument
is that people not doing cryo or at least dry ice will argue that its no better than not using it and for most purposes
can't be proven either way. Good reason for their argument. I do not do a freeze (dry ice or cryo) cause it can
or cannot be proven either way. I do it because I believe as part of the quench it gives me a better product, the
proof I have of this is read on my Rc tester. By being "white" when coming out of the foil means I get 0 decarb
or dark coloration in other words the blades are silver after a frozen plate quench. This can actually cause problems
because collectors like a dark cut long pull or fly cut crescent nail nick, if draw temp isn't high enough the inside
of a cut long pull will remain silver, I've seen makers color the insides of nail nicks chemically to beat this.
Ken.
 
Just something to keep in mind when discussing subzero and cryo treatement. Just as there are many paths to a hardened blade, based on various recipes for the same steel, there are different paths for using the low temperature methods. Many claims are made that seem contradictory, and yet have laboratory data to back them up. The trick I found is that people are using different methods. A maker using either subzero or cryogenic treatment should be able to tell you why and how. From there you can compare to others and see the differences.
 
me2 said:
Just something to keep in mind when discussing subzero and cryo treatement. Just as there are many paths to a hardened blade, based on various recipes for the same steel, there are different paths for using the low temperature method!.s. Many claims are made that seem contradictory, and yet have laboratory data to back them up. The trick I found is that people are using different methods. A maker using either subzero or cryogenic treatment should be able to tell you why and how. From there you can compare to others and see the differences.
Click to expand...

Very well said. A few years ago I did a very informal test of my own, on ATS-34, with sub-zero dry ice treatment. In no way do I feel my own test proved anything one way or the other! What strikes me the most is when I do a Google search, most of the hard data I find is A, fairly dated, and B, offered by someone with a commercial interest in the Cryo business. Does anyone have links to more current data, supplied by truly independent sources?
 
I have a pdf copy of a good technical paper but I have no idea how to add it to the forum !! If I Google the paper I get only abstracts !
 
There are two different processes being mentioned here. One is cold treating and the other is cryogenic treatment. Cryogenic temperatures as defined by the scientific community are temperatures below -244F , so using dry ice is not a cryogenic treatment. Cryogenic treatment uses a slow cool down to -300F or lower. Cold treatments as applied by heat treaters are usually just cooling down to about -120F. Plunging a component into liquid nitrogen is not cryogenic treatment. The part will cool down too quickly and there will not be enough time for the crystal structure to come to equilibrium. If done properly, cryogenic treatment will result in the formation of very fine carbides, the reduction of residual stresses and an increase in wear resistance. How do you test that on a knife blade? It depends on what you use your knife for. Meat packing companies have found that blades stay sharp longer when properly treated, but if you are cutting hardened steel with a knife you will probably not see a huge advantage.

You can read more about true cryogenic treatment at the database of articles and research set up by the Cryogenic Society of America at http://www.cryogenictreatmentdatabase.org/.
 
The people who make most of the newer steels recommend it. They don't take 2 and 3 million dollar race cars apart and redo every bolt on the motor for fun!
 
You must log in or register to reply here.
Back
Top