Cryo testing

[knightsteel]

We did a series of preliminary tests this last week on cryoed vs. un-cryoed blades. We bent and/or broke 9 pieces.

All tests were done using S-7 steel, locking the steel in a vice, and bending using a 4 ft. cheater bar. Typical bend radius was approximately 1/4 inch. Rockwell hardness reflects NO differential temper. Process was a multiwave proprietary sequence.

Thick sections, 0.125":
No cryo, RC57, 30 degree bend, crack
No cryo, RC50, 70 degree bend, crack
Cryo, RC57, 100 degree bend, unbroken
Cryo, RC50, 130 degree bend, unbroken

Thin sections, 0.50":
No cryo, RC57, 60 degree bend, snap
No cryo, RC50, 90 degree bend, snap
Cryo, RC57, 110 degree bend, unbroken
Cryo, RC50, 135 degree bend, unbroken

We finally broke one cryoed piece by switching to a 1/8 inch radius bend.

Thin section, 0.50":
Cryo, RC 57, 120 degree bend, snap


Summary: All 4 pieces without cryo broke. The first four cryoed pieces received approximately double the strain without breaking. Only one cryoed piece broke, but under approximately 4 times the strain as any of those without cryo. (One half radius equals 2X strain.)

Comparative visual study of the cross sections revealed much finer grain structure in the single broken cryoed piece.

It is stunning to note that based on the toughness of the RC50 blades, the cryo allowed use of a greater hardness by 7 Rockwell points and still improved the toughness.

Daniel Watson
http://www.angelsword.com/
http://www.swordarts.com/

 

[tmickley]

That isn't the results I would have expected.
I'd sure like to hear any speculation on why these tests came out like they did.

 

[nhamilto40]

knightsteel:
Please provide link to independent verification and published research.

Thanks.

 

[knightsteel]

Most cryo will convert retained austenite to martensite, but ours is specially designed to push toughness through stress relief, grain refinement, and carbide precipitation. There was originally an increase in hardness, but the steel was also double tempered back to its starting hardness.

Daniel Watson
http://www.angelsword.com/

 

[tom mayo]

This is not surprising, Paul Bos has been subzero quenching every knife he heat treats since the process was introduced many many years ago.

 

[rlinger]

What temp and duration was the cryo??

Roger

 

[tmickley]

I understand that cryo will convert austenite to martensite.
I've not read specifically, anywhere that cryo would refine grain or stress relieve. It is my admitedly limited understanding that proper heat treat at critical temp would limit grain growth and proper tempering would stress relieve and enhance toughness.
I've no idea how carbides could be purposely precipatated intentionally with out changing the alloy content. But then I'm still trying to figure out the whole pearlite nose business.

 

[knightsteel]

Hamilton,

This is the first publication of this data. I am a swordsmith working and trying to push the limits of the steel. These are my personal shop tests.

Daniel

 

[knightsteel]

Roger,

You will excuse me if I hold onto the specific techniques we are using. It is our proprietary formula and involves multiple waves of hot and cold. Deepest temperature was -300F and the entire sequence took about 72 hours. All was tightly computer controlled to eliminate thermal shock. There was no contact between the steel and the LN2.

While I may hold the techniques secret, I also offer cryo services.

My techniques are very distinct from those used by Paul Bos. Busse Combat and Swamp Rat are also secretive about their processes and rightly so. Cryo is a rapidly advancing field of inquiry.

This IS the edge!

Daniel
http://www.angelsword.com/
http://www.swordarts.com/

 

[knightsteel]

tmickley,

Both tempering and cryo can result in carbide precipitation.

Chilling to -120F will convert pretty much all the austenite to martensite. In heat treating terms that is considered "cold treatment".

Chilling to -300F is cryogenic treatment. Old style cryo resulted in a more brittle steel. Done properly the new tech cryo gives stress reduction, grain refinement, and ultra fine carbide precipitation.

Daniel

Link to my general info:
http://www.angelsword.com/cryogenic_processing.html

Link to technical info:
http://www.cryogenius.co.za/Cryo_Tech_Article1.html#Precipitation

 

[TLM]

Carbide precipitation is a diffusion controlled process and the lower you go on temperature the slower does diffusion go. Hmmm...

TLM

 

[nhamilto40]

So lets see what we have here...

1. wild claims for secret snake oil cryo

2. free advertising

3. refuses to provide or allow independent verification

Draw your own conclusion. Remember that extraordinary claims require extraordinary proof.

 

[Laredo7mm]

Originally posted by knightsteel:

My techniques are very distinct from those used by Paul Bos. Busse Combat and Swamp Rat are also secretive about their processes and rightly so.

If they are secretive, how do you know yours is distinct

Or is yours just distinct from Paul Bos?

Just wondering

 

[Dan Gray]

Thank you for the test results
I know that Ln2 works and I've been using it since
I've started using High carbon stainless
but what I'd like to know more about is Liquid helium
now that's some cold gas.
"cold treatment" good .
Chilling to -300F is cryogenic better
Liquid helium ultimate finish treat??
if we're going to push for the best why not
go all the way? $$$

 

[knightsteel]

TLM,

That is frequently given as the reason for extended time in deep cryo. My thoughts are that the carbide precipitation actually occurs during the warming phase. I plan to do some testing to see what happens by varying time at -300F vs. rate of cooling, vs. multiple cycles. To the best of my knowledge no one has defined this yet.

Daniel

 

[knightsteel]

nhamilto40,

Would you care to identify yourself?

Daniel Watson

 

[Colin KC]

Laredo,
Daniel did state that Busse Combat & SwampRat are secretive, but only compared his proceedure against that of Paul Bos.

nhamilto40,
Whilst it does seem that Daniels claims are a little "out there" he has been at this game for a very long time & from what I've seen is a honest & straight dealing guy, a little secretive & (apologies Daniel) IMO a little too mystical, but if he says he did it, I believe he did.

Daniel,
great news, but were these actually made up as a knife/sword, or just bars? It may not make too much difference but I just wondered.

 

[knightsteel]

Laredo,

Paul Bos uses a snap temper followed by deep cryo and then temper and/or double temper.

Actual Busse/Swamprat heat/cryo techniques are difficult to determine but they do state that the process takes 40 hours.

Since our process takes 72 hours it is obviously distinct from Busse.
We also are using multiple hot and COLD CYCLES. I am unaware of anyone else doing that.

In the past most cryo processing has been focused on austentitic conversion. We focus very strongly on grain refinement and carbide precipitation.

The design of our process has very strong metallurgical THEORY. But you never know for sure until you break enough pieces for confirmation.

Daniel

 

[knightsteel]

Graymaker,

If you try anything with liquid helium I would love to hear about it. Right now I have my hands full with both wootz and LN2 experiments.

Daniel

 

[knightsteel]

Thanks Colin.

Because the stresses involved might alter the results, I used almost identical small single edged blades. Bar stock would have worked, but wouldn't have shown if I was getting relief of any stresses built up during grinding, drilling, etc.

As a continuation of this test and independant verification, would anyone like to donate a couple of identical blades for destruction testing? My proposal is for various makers to do identical blades. Send one of them to me for free cryo. (You only pay shipping.) You precisely measure deformation and breakage angles and post them here.

Daniel Watson