Est. 1998 — 27 years of woodworking knowledge
Cryo treatment
Robin Frierson
>Any opinions on the value of cryo treated A2 plane irons vs non cryo treated A2 plane irons. Anyone done any comparisions. I am seeing some difference in edge retention between the two while planing end grain white oak.
Re: Cryo treatment
joel
>All Cryo does is speed up the transformation of the crystal structure of the steel. Initally Cryo blades will hold a finer edge than non-cryo after 6 months or a year they will perform exactly the same. I've actually seen this behavior in my shop and didn't know why until I asked around.
However A2 as an alloy can very between mills and the inital heat treating sequence can also vary between hardening shops. I have seen more variation between Cryo blades of different makers (not good or bad - mostly just different feels - hard to explain) some of the difference are due to thickness but it gets more complicated than that. (And I am clueless on how to explain the differences)
Re: Cryo treatment
Robin Frierson
>So your saying the benefit only last 6 months to a year? I have had some other very knowlegable folks tell me there is no benefit at all.
I was given an article by Chris Schwartz where he states he was told the wear resistance is "permanent". I find it odd that both Ron Hock and Tom Lie-Nielson would go through the trouble of using cyro unless they thought it added something. Maybe Chris Schwartz could pipe in and tell us what he learned researching his article.
Re: Cryo treatment
Alan Hamilton
>Robin,
"I find it odd that both Ron Hock and Tom Lie-Nielson would go through the trouble of using cyro unless they thought it added something."
Or perhaps they cryo treat their tools only because they believe their customers think it adds something. They don't want to be perceived as being behind the times; and they surely don't want their customers to go elsewhere looking for the latest whiz-bang--even if the latest whiz-bang does nothing useful.
Alan
Re: Cryo treatment
joel
>In your second sentence you say that some folks say there is no benifit and in your last paragraph you say that some say there is a long-term benefit.
I'm not sure if the second sentence was supposed to be reversed.
The primary reason for Cryo Treatment is that unless you cryo the blades you have to have them sitting around aging in the warehouse for awhile before you can ship them. So there is a major savings of money in inventlroy by Cryoing the blades. Unless someone has an old non-cryo blade and a cryo-od blade of the exact same steel stock it would be hard to make the comparison on performance.
I happen to have first hand experience of watching a blade age - when I first got it it was ok - after a year it was superb - then someone explained to me about A2.
I have other A2 blades from a bunch of makers - all cryoed, ( I mostly use A2 in my own tools) and in general they last long. My big complaint about the alloy is that is seems more "crumbly" to me and you need a microbevel (or a higher angle)
However overall I am getting much longer blade life at the cost of slightly overall less ease of use.
Re: Cryo treatment *LINK*
Andrew F in Australia
>Joel/Robin,
As the alloy content gets higher in a steel, it gets harder to heat treat completely. To achieve a full conversion to the harder phase, it needs to be cooled quicker and/or to a lower temperature.
One other thing that can initiate transfer is energy from bending, but this is a pretty minor effect
The other variable in transformation is time - things may or may not fully transform after a few months, but what is the benefit in heat treating (tempering) a blade from the brittle hard phase (martensite) to something useable, and then putting it in service, only to find that it's automatically generating more of the hard brittle phase all by itself? Makes things pretty dodgy.
As a piece gets thicker, the cooling rate decreases as there's more heat in the item and it takes a while for heat to diffuse from the hot inside to the cool/quenched outside.
The quality of the heat treatment affects the rate of conversion, which is why tool steels differ between manufacturers.
Attached is a link to something I wrote on this here a couple of years ago.
As well, I think that Rob Lee has something up on the Lee Valley website under the articles section.
Do an archive search on the term 'martensite' in the hand tools archive and you'll get more info, including the Chris Schwarz comments
Cheers,
Andrew
http://www.woodcentral.com/cgi-bin/archives_handtools.pl?read=4444
Re: Cryo treatment
joel
>I read both your old post and the Lee Valley site. The latter seems to agree with me, althought I sharpen A2 without diamond abrasive all the time.
Karl Holtey says that there is a difference in A2 between manufacters.
Since I am not a metalurgist I don't fully understand what is happening when hardening takes place. I can however tell you from practical expericence that the behavior of the steel changes, and all said and done you get a longer wearing edge. But as I said before the edge seems to need a higher angle, which I find effects performance.
Would I go back to regular carbon blades? probably not. Do I wish A2 behaved more like carbon steel - yes. Does Karl Holtey's A2 blade I have perform better than thicker A2 blades from other makers? yes - why I have no idea.
Re: Sources Please -
Todd Stock
>OK - so let me get this straight:
- Percentage of total conversion to Martinsite is identical whether the tool is conventionally hardened/tempered or cryo'd.
- There is no advantage to US or UK cryo treatments other than speed of full conversion.
Please shoot me your sources. As an R&D engineer and system designer, the more technical the better.
Thanks!
What the Crucible Products metallugist said
Bill Tindall, E. TN
>"Some tool steels are near fool proof to heat treat, for example CPM 3V, while others, notably A2, are more difficult to get just right. "Getting all the parts just right is easier with small tool batches than large. And some places have better control of the process than others. (they recommended 2 reliable heat treaters, one in CA and the other in TN.)
Cryo treatment is a useful fix for A2 that has not been hardened perfectly."
The quoted passage is what I remember from the conversation.
Presuming this source, and my memory, is accurate it is no wonder that some find a cryo treatment useful and others do not find it useful. It all depends on the precision of the hardening.
Re: What the Crucible Products metallugist said
joel
>I can't give you a source for the scientific. I've never looked at it from a chemical point of view - I am just reporting on what my experiece has been and the explaination I have been given by actual experts who do this for a living (who spoke off the record because a maker who cryo's their tools can't very well say there is no point and a maker that doesn't sounds like sour grapes).
On the second point my source is my own tests on actual blades, and conversations with several blademakers.
The interesting thing is that the LV web site article on the subject exactly concurs with my own result and they have far more resources for testing than I do.
Certainly if the final performance of Cryo'ed blade is pretty close one way or another to a non-cryo'ed than I would suggest that the difference in performance might have more to do with other factors and Cryo-ing may not be worth the effort except to get a more consistent product to market faster.
Sorry reponse was to Todd's post
joel
>
Re: Cryo treatment
steve knight
>the steel treated makes a big difference too. O-1 has no real benifits if it is frozen. HSS more it depends more on the steel then any other factor. A-2 has been reported to have smaller carbide grains if it is frozen so it sharpens better.
Re: Cryo treatment
Andrew F in Australia
>Hi Joel,
Metallurgy is still a bit of a black art, so steels vary between heat treaters. If you find one that works, stick with them. This would explain Karl Holtey's blades lasting longer.
As well, I seem to recall that the first few sharpenings of an A2/M2 blade don't last as well as the body of the blade - only when you get into the body of the blade do you see full benefit.
Hope that this helps. Once again, from memory, the Lee Valley site does a pretty good job at explaining the metallurgy behind the heat treatment.
Cheers,
Andrew
Links *LINK*
Andrew F in Australia
>sorry for the ps:
Here's the Lee Valley articles - look under most of the subcategories here.
http://www.leevalley.com/home/articles.asp?section=32&action=details&SID=&ccurrency=2
Also linked below is an article that explains cryo treatment - from the Lie-Nielsen website.
Cheers,
Re: What the Crucible Products metallugist said
Todd Stock
>OK - guess I'll do the research and see what comes up.
As to LN/Hock, etc. vs. LV, I doubt it will be the first time that manufacturers have disagreed on process or design issues.
Re: Cryo treatment
Todd Stock
>What research I've done thus far links to chromium content as one of the indicators as to whether cryo will benefit the tool.
A2 is about 4.75%-5.5% Cr, while O1 is under 1% Cr, so I'd expect A2 to be a better candidate for chilling.
Re: Cryo treatment
Andrew F in Australia
>Todd,
The elements that you are looking for in the steel are the so-called Austenite stabilisers, that also decrease the transformation temperature of austenite to ferrite.
Chromium is one of many.
Source: Try a text on physical metallurgy, eg: Reed-Hill is one of the standards, Avner is another
Re: Cryo treatment
Todd Stock
>Cryo treatment sites mention a thin film phenomenon, where a thin layer of metal must be removed to reach the fully hardened material (sounds like at most a few thousanths). I'm pretty sure LN must do final surfacing after treatment, but I wonder about Hock, etc.
Re: Cryo treatment
joel
>Every manufacter of plane irons grinds the blades flat after hardening and heat treating. This is to get rid of any warping of the material. A side effect would be to get rid of any "thin film phenomenoa". Figure about .010" a side worth of grinding.
Re: Cryo treatment
Don Thompson, Cutler Ridge, Florida
>that also decrease the transformation temperature of austenite to ferrite.
For we non-metalheads, does that mean more rust-resistant?
Re: Cryo treatment
Andrew F in Australia
>Hi Don,
Sorry to get too technical there - looks as though Todd was wanting info so I was pointing him in the right direction
Re: Chromium based steels and rust resistance, tool steels don't have enough alloy (except a few exotics) to be rust resistant.
Basically, the 'stainless' part of stainless steel works because they fill the steel full of enough chromium and nickel to allow it to form a surface oxide of (chromium,nickel) oxide, instead of iron oxide. The chromium oxide is nowhere near as reactive as iron oxide, so the layer forms and nothing else happens.
As the chromium oxide layer is thin enough to see through (literally), you see the surface of the steel but protected by the oxide coat.
There are different levels and grades of rust resistance in stainless.
eg: 18/10 stainless (type 316) is used on boats and not affected by salt, but other types of stainless can be affected (eg: type 304, which is the common grade used in cheaper cutlery - I know our cutlery has rust spots where something was dropped into the drawer, like a breadcrumb)
Hope that this explains things well enough to answer the question.
Cheers,
Andrew
Re: Cryo treatment
Fred Krow
>If you heat treat to -300 F you will get an improvement in edge holing and toughness.
The most common treatment is -100 F and this is marginal improvement and was developed for retained Austenite in bearing steels.
Even with O-1 steel you will get a 2x improvement in wear resistance. In addition, aluminum and brass will benefit from -300 F treatment.
The older textbooks and many practicing metallurgists will not accept this fact dueto many personal reasons. The metallurgy department of some steel manufacturers does not recognize the -300F treatment most likely due to published heat treatment data sheets and the fact that they are pushing the newer CPM steels. Recommending Cryo also means additional expense to the user of the steels.
Search Google for "cryo treatment steel" many advertizements from heat treaters and hidden away are some interesting papers on research data from -300F cryo.
Regards,
Fred Krow