Cryo and 3v.

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petah

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Now without opening a can of worms here... The Cryo debate... I know of a paper floating around about how it's not that great on some tool steel (Fitz has a copy)

Has anyone ever tested 3v?
I read conflicting reports stating it leads to premature failure (when bending) or that it does absolutely nothing... any first hand experience from a makers point of view?
 
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I say let the heat treater worry about it. The crucible datasheets don't mention cryo, so I wouldn't bother with it.
 
Paul Bos 3v ht:

Austinize @ 1875 -2000 deg. F ,Hold at temp for 30 min. Air or interrupted oil quench to about 1000 deg. F.then air cool. I suggest air quench. Air quenched from 1950, temper at 950 will give you a R\C of about 61. 3 temper min. You can do a sub-zero after first temper. Two hrs. per temper. Paul.


I have no idea if the cryo is a good thing on 3V or not...
 
With the recommended heat treat, you are already doing multiple tempers of 3V at 1,000 degrees Fahrenheit and above, I don't think cryo would help you reduce retained austenite, but that's entirely conjectural.
 
Are you asking from an experimental perspective or a production perspective?

Experimentally it would be great for someone to do it and report the results.

From a production perspective, the issues would be the added cost and the increased potential for cracking.

And philosophically, the argument "why not do it anyhow?" has an unlimited number of candidates (e.g. only heat treat with the blade pointed north/south during a full moon) that make it hard to pick.

If someone wants to grind a set of identical blades or other test samples, I'll be happy to pay for the various heat treatments from Paul Bos along with some basic metallurgical analysis of the results.
 
Crucible has probably already done the metallurgical testing on any effect of cryo on 3V. Perhaps a phone call to Scott Devana would result in a manufacturer's recommendation and maybe even some data.
There is also more likelihood the tests would have been done more statistically meaningfully than a single point determination on a pair of blades. That is always so fraught with uncertainty.
It's a very generous offer, Gabe, but I would be afraid a test of that limited scope could result in creating unjustified conclusions.
 
fitzo said:
Crucible has probably already done the metallurgical testing on any effect of cryo on 3V. Perhaps a phone call to Scott Devana would result in a manufacturer's recommendation and maybe even some data.
Click to expand...

Mike just mentioned the reason for me saying I wouldn't bother with cryo, Crucible has most likely tested it. They don't seem shy about recommending it in their datasheets, so I have a feeling they already determined that there is little or no benefit.
 
Unless you have a perfect heat treat I'm thinking cyro is going to help. I understand that some field tests have shown questionable improvement on carbon steels (as compared to "modern" stainless steels) but there has been some improvement shown in nearly every steel in testing data I've read.
 
Hey Tracy - I see where you're coming from, but let me play devil's advocate here. With the fairly demanding heat treating regiment of 3V, wouldn't you agree that any reasonably experienced heat treater is going to come awfully close to perfect? If we combine this with plate quenching and high-heat tempering, my guess is that retained austentite is fairly unlikely in this steel.

The reason I trust the crucible data so implicitly is that they are very quick to recommend cryo on their steels. My book shows cryo benefits in most steels that we work with: A2, D2, O1, 440C, 154CM, etc. There also seems to be a common thread with tool steels that don't suggest cryo, the high-heat temper. M2, M4, 3V and the like are all in the 1000F tempering range and none have cryo notes in my data.

This is turning into an interesting thread,
Cap
 
Remember that all we KNOW that cryo will do is reduce retained austenite. Tempering at 1000 F will do that quite well in most steels..
 
mete,
I am shocked that a person of your learning hasn't read the extensive writings of Georg Arnesson on this subject. It seems that at about 144.11 Kelvin the gates of Aasholm open up temporarily allowing the Gnomes to enter the world of steel. This gives the blades legendary power and the ability to destroy the Gollum. While this is not a current requirement in modern blades, the advantages of cryo can't be taken lightly.

Plus, it is good for the LN industry and makes great marketing for the sale of genuine Ninja swords.

Stacy
 
ive done both with and without cryo

at 1000f temper
and just with cryo then tempered at 400f (didnt trust non cryo and temper 400)

guess you kind of just have to play with it and see what works for the blade in question
 
Butch makes an excellent point. You have to experiment and decide for yourself.

For my part, if someone wants an air quench blade done without cryo, they get an email stating that, while it is contrary to my recommendation, I'll be happy to heat treat to their standards.

It has often been mentioned on here that those who support cryo stand to profit from it. It is also likely that many of those who oppose it aren't able to offer it.

Follow the money - and then listen to Butch. :)

Rob!
 
I think the important point about experiments was made by Mike above, we need a large enough data set for it to be meaningful. If we really want to test this stuff we'd need 10's of samples of each heat treatment at the very least.

Maybe Rob would be willing to heat treat 20 test squares for us and then we could find someone here on the forums with the resources would be willing to do analysis.
 
I don't think cryo on guitar strings makes them sound better. I don't think cryo treated leather boots last longer. I do think cryo treated carbon steel changes and has improved wear characteristics through better conversion to austnite from martinsite. Nothing else. I don't think it aligns molecules, changes the entire crystal lattice, refines grain or what ever there is. I also don't think edge packing steel while forging improves grain structure, aligns molecules or gives an improved crystal lattice - but that is another issue. Several years ago I spent a lot of time researching cryo on the internet, reading the dullest damn research papers you could imagine. I think the results are there and proven and it's worth doing. I also know a lot of people think it's hooey. I've got no problem with that myself and I'm not going to argue with them for one second.
If you can get a perfect heat treat on a carbon steel, don't cryo it. It's a waste of money. You'll need an electron microscope to verify your results or that gizmo that Cashen uses. On the other hand, can it hurt to be sure?
I have nothing to gain by promoting cryo treatment.

Why would Paul Bos use cryo if it doesn't help?
 
Hey Tracy - definitely wasn't trying to argue against cryo in all circumstances or meaning to offend. Just talking about this particular situation. I do believe that cryo helps many steels out there, I'm just on the fence about many of the high-heat tool steels.
 
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