Cryogenics for sharper knives?

This whole thread has been tremendously educational. Cliff, is there any sites on the net that have articles about cryogenic treatment as it relates to knife blades? It seems that almost all of what you find is written about it's effects on tools. I sure would like to learn more about this. If you could recommend some books that one could read, that would also be greatly appreciated.

Once again Cliff, I would like to thank you for the amount of knowledge that you gather and share with the rest of us. Your writtings have taught me more about steel and how it relates to the knife industry than any other source that I have found.
 
Dan: Thanks: That is what helped me come up with the thought. Used to work for an outfit pouring cement for interstate overpasses, we had to have so many pounds of each sice rock and sand, weied every wheel barrow full. the inspector stated that is what made for flexability.
 
KWM, there is not a lot of dedicated research done on cryogenics on knife blades, mainly I assume, because that is such a small part of the industrial use of steel, and it is the properties of the steel you are interested in, not the specific application when you are looking at heat treat method. Most of what I have learned about cryo and heat treating in general just comes from reading journals and the papers presented at conferences. I then spend a lot of time talking to various makers to get some feedback on applications.

I spent a lot of time before last christmas specifically looking at the effect of forging from a materials point of view to understand why and how it can give benefits to the knife maker, as well is there any real merit, materials wise, to multiple quenching as from a very basic viewpoint it should not do anything. As well as various other techniques and issues like the use of rare earth metals, and the influence of plastic deformation *during* the heat treat cycle. A lot of excellent research has been done. Hopefully I will get some more time the summer to look at such topics again.

It is a good point though that it is not trival to determine what properties give the best material for a particular application. For example in knife blades, because we want to use knives when they are very close to optimal levels of sharpness, edge retention is dominated in the short term by resistance to rolling, as even a microscopic edge roll can reduce the cutting ability for fine work down to a few percent of optimal. However for a lot of industrial blade applications, the edges are not used near maximal sharpness, and wear resistance is the major factor.

As for grain size, when a steel is of grain size x microns, this doesn't mean that all grains are x microns, it just means the average size if x microns. Small grains increase the strength of the material, and larger grains increase the ductility and impact toughness. Thus large grain inclusions in small grain steel makes it touger and more ductile. There are complications to this of course, and as always you ride a delicate line between strength and toughness.

-Cliff
 
Many complications influence research. A lot of them are virtually unmeasurable due to the obscurity of their initiation. For example, a difference of 35 degrees in melting temperature can influence the nature of the steel for ever more. This is undetectable by examining the chemistry or microstructure as these are usually measured. Compare a blade from one batch to another with a slight difference in chemistry, the manifest difference can be much greater due to variables that we are not aware of than the chemical difference we intend to explore.

This is why when we find a good melt of steel that we can come to understand, it is absolutely necessary to buy as much of it as possible. The reason why it works so well may be obscure, but it works and that is what matters.
 
Tru words Ed. What a lot of people don't know or forget is that metalurgy is still much of cook book effort. You make a material out of some alloying elements and then investigate the properties. In spite of what some individuals say about developing computer progranm to produce proprietary steels, I have set to see any thing come of these compounds other than magazine articles.
As far as cryongenics goes, the rifle barrel industry has been using cryogenics as hype for some time now. Steels need to be quenched to 'freeze' in the structure you want and the rate of quench, temperature and holding points can influence the properties of the final material. In many cases though, I would think, when you get below a certain temperature, you really will not get any additional effect, simply because large scale atomic movement has stopped. The alloying elements, grain boundaries and dislocations don't move. The best way to do things is how you(Ed) have been proceeding, by accurately measuring and recording the variables that go into producing your blades for repeatability. -Dick
 
Rifle barrel Cryo treatment is not hype. The misunderstanding is claims of increased accuracy by some makers. The chrome moly or stanless barrel will give significatly longer life befor accuracy falls off to unaccepable levels. In a benchrest rifle the accuracy is lost at 1200-1800 rounds, with Cryo we have continued to 3000-4000 and some higher. This is long cycle -300F cryo, not dunk it in some nitrogen or dry ice for a while. What is physically happening to the crystaline structure is not explained very well.

Practical testing with -300F shows automotive engine components last much longer in racing engines, carbon steel and stainless steel razor blades last several times longer, brass musical instruments change to the delight of musicians.

This is much more than the classical retained Austenite in high carbon bearing steels as the older textbooks describe. Twenty years ago the -100F was considered cryo, today it is the long cycle to reach -300F hold at that temp and long cycle to ambient temp. Perhaps this relatively long time for delta T is where the physical property enhancement is developed.

Regards,
FK
 
Ed
funny how all things interact with
same differences with in their structure.

 I don't agree Dick
 I believe the colder the better
tests show -100 deg is better the -0 deg.
cold slows the molecules and in slowing them down, it seems
to have a positive effect on the over all use of the
 blade cutting, sharpening and tufness..for whatever reasons.
 on reg say O1 you have to reach +1550. quenched to around +100 deg.
 or it won't work to peak ??? (for lack of word for it ) so who's to say
 - 1550 wouldn't help even more.

being that -320 is the coldest we can go and the
molecules are not stopped yet at this temp, there is more
testing to do.
though it may not make a big difference to most users
quenching from -200  to -320 deg,

it does for the maker in the quest for the best knife ever.
I do wonder what -500 would do???
 someday when we can achieve that lack of temperature.
 This is science and we have many things to learn yet.
 
A note for absolute zero temperature and the -300F we are discussing for cryo quench. Some misconceptions are apparent with above postings. We still have molecular energy at -300F. A questions as posted above, what will happen to the steel at even lower temperatures?

http://www.pa.msu.edu/~sciencet/ask_st/012992.html

http://www2.rhbnc.ac.uk/~uhap057/LTWeb/Absolute.html

http://www.ilpi.com/msds/ref/tempunits.html

http://www.mmsonline.com/articles/0301rt2.html


And for the Physics majors:

http://www.duro-chrome.com/roleof.htm

Regards,
FK
 
FK
If your referring to my post
I did state there was still molecular energy ( movement) at -320F
 quote" -320 is the coldest we can go and the
molecules are not stopped yet at this temp, end of Quote.

I should also say here on Earth
and going on to say

quote" from your links..
The lowest temperatures which occur (naturally) are on Triton in the
 Solar System and in inter-galactic space.

Much lower temperatures can be created in the laboratory,
but not as low as Absolute Zero!
(at O K  not 0 F or O c)
  this is the measurement that we don't normally use converted.
extrapolates to zero for T = -273.15deg.C, now written as 0 K (degrees kelvin). the temperature of intergalactic
molecules of cyanogen (C2N2)
has been measured directly as 2.73 K,
 in thermal equilibrium with the cosmic background radiation
 (this was first discovered 50 years ago, but no explanation was
 then available). This is the lowest natural temperature but is available only in deep space. Lower temperatures require intelligence
 (or at least physicists).
I don't see any misconceptions ?? please if your referring to my post
please point them out to me. I intend not to misslead anyone.
 
I don't want to get into a pissing contest with anyone and don't want to flame anyone but I will make some comments. Absolute Zero cannot be obtained but one can come close. At this temperature and atomic distances, quantum mechanics come into being and things are not what they seem. When you make statements like "I think" and "I believe" that are not based on science or an understanding of science, or properly conducted and documented testing, you are not making any sense. To truly understand the physical sciences you have to be able to work the math, which means calculus and many other mathematical treatments. When testing processes like cryo treating of rifle barreles and the effect on accuracy, you must make sure the tests are conducted correctly which takes scientific training and understanding of how the test set up and your prejudices can color results(COLD FUSION for example). I have not seen any reliable testing for the cryo results or any scientific reason for extending barrel life. It looks like razor blades under a pyramid to me. Graymaker, I don't know what the hell you are talking about. The temperature of space that you refer to is the background radiation left over from the Big Bang which has cooled to that temp since the Big Bang measured by the COBE Explorer(satellite), the rest sounds like Mumbo Jumbo to me. -Dick
 
Originally posted by budrichard
I don't want to get into a pissing contest with anyone and don't want to flame anyone but I will make some comments. Absolute Zero cannot be obtained .... When you make statements like "I think" and "I believe" that are not based on science or an understanding of science,
or properly conducted and documented testing,
you are not making any sense.
Graymaker, I don't know what the hell you are talking about. The temperature of space that you refer to is the background radiation left over from the Big Bang which has cooled to that temp since the Big Bang measured by the COBE Explorer(satellite), the rest sounds like Mumbo Jumbo to me. -Dick
Click to expand...

now I'm not Mad dick I have a smile on my face right now
just so you know..

If you'd look,, it was quote
That I wrote.
I'm very sorry next time I'll say (again) it's my opinion,
in the stead of (I believe ) maybe we should not give out Opinions in the forums??
Most of what we do is based on other makers opinions ,, only my opinion again Here..
As far as, we in the shops we'll use L/ nitrogen,. it's all we have right now to use..

we (most people,) under stand farenhight and Celsius temperatures
not ...degrees kelvin...<<this was agian quotes from higher up than my small intellect.

This may be the mum-bo jum-bo you don't under stand.

As for the Big bang... this in your own words
as you said here
you must make sure the tests are conducted correctly which takes scientific training and understanding of how the test set up and your prejudices can color results.

Is this to say that you know of the big bang ??
this is only one theory (not a fact) there are more than this one theory.

You're saying not to do this and your doing the samething here.

enough said on my part. most of what I said was to back up
the other post I did, because of miss under standings in the post.
It's getting more in depth than most can or want to understand.

Please disregard anything that I've posted here..I apologize for it..
As you can see I'm not a writer ether..
 
FK, The American Rifleman published the results of cryogenic applications versas rifle barrel accuracy in the last year. They could find no statistical change in accuracy. From reading the test, it looks like it was well done. I'm sorry I don't have the issue reference but that shouldn't be to hard to find.
Graymaker- I'm glad you are still smiling.
Dick
 
Originally posted by FK
The chrome moly or stanless barrel will give significatly longer life befor accuracy falls off to unaccepable levels. In a benchrest rifle the accuracy is lost at 1200-1800 rounds, with Cryo we have continued to 3000-4000 and some higher. This is long cycle -300F cryo, not dunk it in some nitrogen or dry ice for a while. What is physically happening to the crystaline structure is not explained very well.
FK
Click to expand...

I believe the point of FK's post was that barrel life, i.e. the number of rounds shot before some given loss of accuracy, was what improved with cryo. Not any improvement in overall barrel accuracy.

I did not read that American Rifleman article so don't know if they looked at life, or just accuracy. Different issues.

~~~~~~~~~

Great thread by the way. Thanks to all who contributed info... much of which I stashed in a Word document for my archives.
 
I've done a bit of benchrest shooting myself. Fun stuff! From everything I can gather from all the old timers who have been shooting for years, cryo'd barrels do offer a little bit longer life. No increase in accuracy, but a bit of an increase in the amount of time it takes to "shoot out" your barrel.
 
Ed Fowler :

For example, a difference of 35 degrees in melting temperature can influence the nature of the steel for ever more. This is undetectable by examining the chemistry or microstructure as these are usually measured.
Click to expand...


Research in the materials industry on heat treating and composition is not simply done by looking at the steel under a microscope. Yes this is a part of it, as the basic idea is to understand how the crystal structure creates the properties, but it is not the whole process. The effects of time, temperature and composition would be looked at by how they effect the materials properties, which include but are not limitied to; tensile strength, impact toughness, ductility, wear resistance, corrosion resistance, etc. . These properties would then be examined in conjunction with the crystal structure and of course an understanding of the benefit of the properties to the task for the material, which isn't by any means trivial.

As for the cook book, it is very true that currently the understanding isn't at a level where you can for example write out a steel of a given alloy and ask for specific properties given a certain heat treatment. However there are general laws on how various alloy elements effect properties and to what extent. You can for example find statistical rules for critical points given the alloy composition. As with anything, the theory is just a guide to experiment. It should be use to form the starting point, as well as to guide progress in experimental work by pointing out how to procede in general, possible areas of refinement and interesting roads to explore. Cryo for example is obvious once you look at the transition temperatures for high alloy steels.

As for temperatures below liquid nitrogen, it is very possible, Helium is commoly used for example, however it is much more expensive and thus I have not actually read any results of it for cryo treatment.

-Cliff
 
Cliff Stamp said:

As for grain size, when a steel is of grain size x microns, this doesn't mean that all grains are x microns, it just means the average size if x microns. Small grains increase the strength of the material, and larger grains increase the ductility and impact toughness. Thus large grain inclusions in small grain steel makes it touger and more ductile.
Click to expand...

Hmm, a mixed grain. My oh my, who would ever be interested in that concept? :cool:

-Jason
 
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