LN2 an inferior method of an extended quench question

[rodriguezryan14]

So basically I was told by a member here that our process of a liquid nitrogen dip wasn’t a good process, and basically that another big company that starts with a B and ends with an se has a superior method. I’m not saying they don’t, and am I in no way insinuating that an ln2 dunk is better in any way. But it seems that people are under the impression that the way most of us custom makers are extending our quench is not a good method. I’d like to just get an idea of how many failures people have had with the methods we use!! For example, I plate quench in foil, when the blade cools enough, I remove it from the foil, put it between two more cooler plates till it’s cool enough to pick up bare handed, then it goes into a bucket of water to cool down further, then into my deware, anywhere from 30 minutes to 8 hours. From there it goes into temper, I usually triple temper everything I make. I’ve yet to have a failure of any sort in the 4 years I’ve been making knives! But people seem to be under the impression that this method is inferior!! I’m confused! Is this just marketing at its finest? Seems like more hype to me!! I’d like to hear from others, your thoughts

 

[DevinT]

What are they saying is the superior method?

Hoss

 

[rodriguezryan14]

What are they saying is the superior method?

Hoss

Dunking blades in liquid nitrogen vs dare I say the name, I know Larrin got a lot of crap for even opening this can of worms. The maker of the infamous infi steel. They’re basically saying that that maker’s method of deep cryogenics is superior to anything we use! But this has pretty much been debunked by Larrin. And this super duper superior heat treat methodology!! Lol. Maybe this was something I never even should have started. But it’s because I want to hear if people have actually had any failures! I know I haven’t!

 

[A.McPherson]

Blood of Virgins on a full moon in January.

 

[DevinT]

In all of the toughness testing that we’ve done, we haven’t detected any problems with using a direct cryo quench.

There might be some benefit to cooling slowly but we haven’t done any testing yet.

Hoss

 

[rodriguezryan14]

Thay

In all of the toughness testing that we’ve done, we haven’t detected any problems with using a direct cryo quench.

There might be some benefit to cooling slowly but we haven’t done any testing yet.

Hoss

That’s basically what I’m getting at! I haven’t had any issues in my personal testing either! And I test a lot of my blades that I heat treat!

 

[rodriguezryan14]

Blood of Virgins on a full moon in January.

I thought it was December. But I could be wrong!! Lol

 

[Stacy E. Apelt - Bladesmith]

The issue is - We Make Knives ... We don't make rocket parts or crane gears.
Our product has only one need - a hard and tough edge.
If we leave a few % of this or that behind in our methods, it really won't matter in the end.
It is pretty much the same as forge HT vs HT oven. Yes, a programmed HT oven will do better, but both will make a good knife.
A $50,000 cryo cooler with programmed temperature drop is undoubtedly better, but cooling almost instantly to -320°F works just fine for knives.

 

[hugofeynman]

What are they saying is the superior method?

Hoss

Bringing the piece slowly to the lowest possible temperature, let it rest there and then slowly bringing the piece to the room temperature.
I don’t want to bash or disrespect anyones work, including makers and persons I admire, like you, rodriguezryan14 , but that slow descend makes more sense to me…
Having said that, I understand that cryo should be done right after quenching to avoid retained austenite to stabilize, so your rapid cryo dipping makes sense… The more I read, the less I know…

 

[hugofeynman]

The issue is - We Make Knives ... We don't make rocket parts or crane gears.
Our product has only one need - a hard and tough edge.
If we leave a few % of this or that behind in our methods, it really won't matter in the end.
It is pretty much the same as forge HT vs HT oven. Yes, a programmed HT oven will do better, but both will make a good knife.
A $50,000 cryo cooler with programmed temperature drop is undoubtedly better, but cooling almost instantly to -320°F works just fine for knives.

And I fully understand that, but some guys want to run the extra mile… and others are willing to pay for that…

 

[hugofeynman]

The issue is - We Make Knives ... We don't make rocket parts or crane gears.
Our product has only one need - a hard and tough edge.
If we leave a few % of this or that behind in our methods, it really won't matter in the end.
It is pretty much the same as forge HT vs HT oven. Yes, a programmed HT oven will do better, but both will make a good knife.
A $50,000 cryo cooler with programmed temperature drop is undoubtedly better, but cooling almost instantly to -320°F works just fine for knives.

Now I understand when Cliff Stamp said “cryo is expensive.”! He was talking about that kind of equipment.

 

[fitzo]

 

[rodriguezryan14]

Bringing the piece slowly to the lowest possible temperature, let it rest there and then slowly bringing the piece to the room temperature.
I don’t want to bash or disrespect anyones work, including makers and persons I admire, like you, rodriguezryan14 , but that slow descend makes more sense to me…
Having said that, I understand that cryo should be done right after quenching to avoid retained austenite to stabilize, so your rapid cryo dipping makes sense… The more I read, the less I know…

It wasn’t you, it was that other guy that basically said our method was inferior. Maybe busse has a better method, but they’re not necessarily getting better performance than other makers here. And this isn’t a busse or infi bash in any way. They do make some good products. But I’ve tested my heat treated blades next to theirs, I haven’t seen a difference, as a matter of fact my A8 seems to hold up better. Not destroying either, but overall hardness and edge stability! I only have one infi knife these days to compare though. Most custom makers spend a lot of time refining our process to get the best results we can with the equipment we have.

 

[rodriguezryan14]

I

The issue is - We Make Knives ... We don't make rocket parts or crane gears.
Our product has only one need - a hard and tough edge.
If we leave a few % of this or that behind in our methods, it really won't matter in the end.
It is pretty much the same as forge HT vs HT oven. Yes, a programmed HT oven will do better, but both will make a good knife.
A $50,000 cryo cooler with programmed temperature drop is undoubtedly better, but cooling almost instantly to -320°F works just fine for knives.

I agree completely Stacy

 

[DevinT]

I think that the slow cooling in the heat treating process is more pertinent for complex dies which have varying wall thickness and guide holes etc. It’s the same reason why they slowly heat up the die and let things equalize before austenitizing.

Quenching from ~2000’f down to ~72’f would seem to be a lot more severe than going from ~72’f down to -320’f.

Knives are thin narrow tools and are not affected as much as complex dies.

Hoss

 

[rodriguezryan14]

I think that the slow cooling in the heat treating process is more pertinent for complex dies which have varying wall thickness and guide holes etc. It’s the same reason why they slowly heat up the die and let things equalize before austenitizing.

Quenching from ~2000’f down to ~72’f would seem to be a lot more severe than going from ~72’f down to -320’f.

Knives are thin narrow tools and are not affected as much as complex dies.

Hoss

You, Stacy and Larrin are a wealth of knowledge. And I do appreciate any of your responses!!
Heat treat and metallurgy is my absolute favorite part of knife making, experimenting with different hold times, different temps, etc!! I’m always trying something different, and testing it myself. Always trying to improve!!

 

[Natlek]

You, Stacy and Larrin are a wealth of knowledge. And I do appreciate any of your responses!!
Heat treat and metallurgy is my absolute favorite part of knife making, experimenting with different hold times, different temps, etc!! I’m always trying something different, and testing it myself. Always trying to improve!!

How you testing ?

 

[fitzo]

I'd love to read and absorb the scientific study (-ies) that establishes the validity of slow versus rapid cryo cooling for the alloys used by custom knifemakers. Anyone have a link that isn't the paper from the Park City IL company with the nebulous Eta-carbides precipitation explanation? Or, for that matter, independent confirmation of the theory behind the claim. I'd really appreciate it. I can handle the tech lingo okay I believe. Thanks.

 

[Larrin]

Slow cooling means less chance for warping or cracking but slower means there is more time for RA to stabilize and therefore the cryo treatment can be less effective. Most cryo studies do one or the other (dunking or slow cooling) and very few compare them. Many times when people claim a paper shows that slow cooling is superior cite a study where they perform slow cooling but do not compare with other cooling rates.

 

[hugofeynman]

Slow cooling means less chance for warping or cracking but slower means there is more time for RA to stabilize and therefore the cryo treatment can be less effective. Most cryo studies do one or the other (dunking or slow cooling) and very few compare them. Many times when people claim a paper shows that slow cooling is superior cite a study where they perform slow cooling but do not compare with other cooling rates.

Less chance of cracking! So there’s a chance of cracking! Precisely what a knifemaker that I respect told me once, that’s why he prefers to use high temper to remove RA.