The "Cryo" update

[Angus Trim]

I thought I'd take the time and catch folks up on the progress, or lack there of, on the "cryo" experiments that I've been a part of.

I've been involved in a series of different treatments, from just plunging a blade into -100F after the quench, then normal tempering, to a series of cold treatments {-100 and -300} and tempering treatments. Some of the custom gun guys swear by the "series" stuff...........

Well, actually, all I noticed with just the plunging into the cold was a funky blue color overlaying the ussual black. Maybe the edge is a bit softer......

Since we've started the "series" stuff, I have noticed a difference. The edge is definitly softer. The "ussual" harden/ quench/ temper route we do generally gives me a 52rc body, and the edges are ussually 3 to 4rc harder than the main body. After the "series" treatment, the whole blade is a bit softer....

We've done this now, enough to start feeling a pattern. If the body of the control blade tests 52.2rc, the body of the blade that went thru the temper- cold - temper -cold - temper routine is ussually 51.8rc. If the edge of the first tests 55rc, the 2nd now tests 52rc.

Oddly enough, it seems that the blade that was sent to Angel Sword did the same thing. Its softer than the "control" blade, though not enough to panic over.........

On the stuff done here locally, there doesn't seem to be an advantage to "flex", nor impact resistance. And the edge holding seems to have lost a bit. Not sure that this is the way I want to go........

There was one test, where the cryo'd blade bent further before taking a set, and held up better before snapping. But the difference was like 5%. And checking the wreckage after the fact, there was .01 inch difference between the two blade's thickness, which may have more to do with the different results than the cryo series...........

Now, this may not mean much as to how much a good cryo series like Angel Sword does, will help the average smith or swordmaking firm. Most folks and heat treating firms do not do things as meticulously as the heat treater I use. There is very little retained austenite in my blades, where you will find a decent amount in most blades made today........ As an aside, I believe that Angel Sword's service could add value to a lot of blades out there.........

Not that there is anything real special about the way my blades are heat treated. The heat treat is actually very basic, just very meticulous. A reasonable quality for the dollar spent........There are smiths out there who do a better job on their favorite steels, fellas like Kevin Cashen and that rascal Howard Clark. But, for every KC or HC out there, there are several who could use some help.......

My very politically incorrect opinion..........

Auld Dawg

[Robert C]

What steel did you start with ? Are you saying cryo treatment makes the steel softer ?? I would call 0.5 Rc difference within experimental error, but 3 Rc difference significant.

[John Lundemo]

Dear Gus, I know your thurst for perfection has taken you into some strange waters. The Hot oil quench which you described to me that your factory boys out by you do, is very close to my own custom heat treat that I do for all my blades. This process is known in the custom sword and knife community as being the optimim method in bringing the steel in question, in your case 5160, to the farthest reaches of it's capability. The added cryo treatment is used alot in the treatment of steels like 440c and ATS34 which are the most popular stainless steels used in the custom knife market, and in those steels this treatment does make a slight difference. But, cryo is just not used for spring or alloy spring steels as it is not needed. The smith you mentioned Gus, uses S7 steel for the most part and this complex tool steel is generally not used for anything anywhere else but knives. It is extemely hard to get the high hardness and spring at the same time needed for sword blades. I've used it several times with mixed results, perhaps this particular steel needs the added treatment to atcheive the kind of spring and hardness that 5160 and 1075 deliver consistantly when treated in the 350 to 400 degree quench and temper at same for an hour or so. Why you tryin to fix what ain't broken?

[Angus Trim]

Originally posted by Robert C
What steel did you start with ? Are you saying cryo treatment makes the steel softer ?? I would call 0.5 Rc difference within experimental error, but 3 Rc difference significant.

Hi Robert

Started with the same steel I wound up with....5160 *g*.

Since the harder edge than body is just a by product of the heat treat, I'm not sure that I would say that the cryo is really making the steel softer. Maybe making things more consistent would be a better way of looking at it. The edge hardness after the cryo series seems to be real close in hardness to the body.

[Angus Trim]

Originally posted by John Lundemo
Dear Gus, I know your thurst for perfection has taken you into some strange waters. The Hot oil quench which you described to me that your factory boys out by you do, is very close to my own custom heat treat that I do for all my blades. This process is known in the custom sword and knife community as being the optimim method in bringing the steel in question, in your case 5160, to the farthest reaches of it's capability. The added cryo treatment is used alot in the treatment of steels like 440c and ATS34 which are the most popular stainless steels used in the custom knife market, and in those steels this treatment does make a slight difference. But, cryo is just not used for spring or alloy spring steels as it is not needed. The smith you mentioned Gus, uses S7 steel for the most part and this complex tool steel is generally not used for anything anywhere else but knives. It is extemely hard to get the high hardness and spring at the same time needed for sword blades. I've used it several times with mixed results, perhaps this particular steel needs the added treatment to atcheive the kind of spring and hardness that 5160 and 1075 deliver consistantly when treated in the 350 to 400 degree quench and temper at same for an hour or so. Why you tryin to fix what ain't broken?

Hi John

Actually, in the case of Angel Sword, this is a part of the two swords being risked, vs the one for Angel Sword as part of the cutting/ destruction thingie over on AxeForum.

As far as the local stuff, this is returning a favor. Jim seems to think I'm a no nonsense guy when it comes to this, so he wanted someone besides the knife guys and the kustom gun guys that are raving about this, to try it out and tell him what's going on from another perspective.

One of the local knife guys has been claiming that this stuff along with his new fangled bang up steel has made his hunting knives "five moose knives". Meaning you can skin and clean five moose between sharpening..... Ussually you can't make it all the way thru the one time without having to stone the edge........

Then there's the guy that claims an additional 100 horsepower if the block, piston assys, cranks, etc get cryo'd. Nothing else mind you, just the cryo.......

Then there's the gun guy that will tell you how much more accurate and stable his gun barrels are after a cryo series.........

Maybe so..........

But it doesn't seem to turn 5160 sword blades into indestructable objects...... Not much change at all....

Maybe for the guys that get a lot of retained austenite it would help, but hasn't been much difference here.

[D. Opheim]

Originally posted by Angus Trim


Maybe so..........

But it doesn't seem to turn 5160 sword blades into indestructable objects...... Not much change at all....

Hey Gus, i'm not compleataly surprized by the results, but you mentioned "plunging the blade into (add temp >here<), so does that mean its litterally "dipped" or was another method used?

I'm wondering about the method of "dry quenching" where the blade is litterally stuck in a freezer from room temp to -300 over the course of several hours; then is is allowed to "thaw".

I don't know for sure if either method is better than the other or if there are different results, but I though I would mention it to see if it was done as well.

It would be cool to see some pics of the blue/black blades. Is the color change perminate?

[Jeff Ellis]

Originally posted by Angus Trim
Hi John

Actually, in the case of Angel Sword, this is a part of the two swords being risked, vs the one for Angel Sword as part of the cutting/ destruction thingie over on AxeForum.

As far as the local stuff, this is returning a favor. Jim seems to think I'm a no nonsense guy when it comes to this, so he wanted someone besides the knife guys and the kustom gun guys that are raving about this, to try it out and tell him what's going on from another perspective.

One of the local knife guys has been claiming that this stuff along with his new fangled bang up steel has made his hunting knives "five moose knives". Meaning you can skin and clean five moose between sharpening..... Ussually you can't make it all the way thru the one time without having to stone the edge........

Then there's the guy that claims an additional 100 horsepower if the block, piston assys, cranks, etc get cryo'd. Nothing else mind you, just the cryo.......

Then there's the gun guy that will tell you how much more accurate and stable his gun barrels are after a cryo series.........

Maybe so..........

But it doesn't seem to turn 5160 sword blades into indestructable objects...... Not much change at all....

Maybe for the guys that get a lot of retained austenite it would help, but hasn't been much difference here.

So basically Gus, cryo treatment doesnt do anything if the blade is heat treated right in the first place? Or did i misread something?

i never understood how freezing the blade could help at all.. i was under the impression cold actually made the blades brittle.....

[Robert C]

Jeff, in fact there are production knives that are cryo'd to make up for poor heat treating . All of this of course goes back to the fact that the basic reason for cryo is to reduce retained austenite but you wouldn't expect ( at least I wouldn't ) any retained austenite in 5160. Too high a hardening temperature will produce retained austenite at least in some alloys. Don't confuse cryo , a heat treatment, with properties such as brittleness, at low temperature.

[Jeff Ellis]

Originally posted by Robert C
Jeff, in fact there are production knives that are cryo'd to make up for poor heat treating . All of this of course goes back to the fact that the basic reason for cryo is to reduce retained austenite but you wouldn't expect ( at least I wouldn't ) any retained austenite in 5160. Too high a hardening temperature will produce retained austenite at least in some alloys. Don't confuse cryo , a heat treatment, with properties such as brittleness, at low temperature.

yes but if all is done right in the first place the cryo shouldnt be needed. right?

[Glen C.]

"Then there's the guy that claims an additional 100 horsepower if the block, piston assys, cranks, etc get cryo'd. Nothing else mind you, just the cryo......."

Thanks Gus, I was waiting for the chuckle of the day and this was it Now, polishing intakes and head ports makes some sense but that just plain cracked me up. Honest, I don't want to hijack the thread (don't get me started).

Some claims of thermal treatments are really kind of wacko but there may be some steels that do benefit. I'm more willing to listen to the folks that have been in the business for awhile (Like Mike Stewart of Bark River Knives) than the grinder that is using his refrigerator freezer between multiple tempers. Large production companies like Spyderco may reap a benefit of equalization when running large batches of blades.

Whaddoiknow?

Cheers

Hotspur; knew someone that would sift through hundreds of rocker arms for a matched weight for eight (easier than grinding them)

[David Stokes]

Originally posted by Angus Trim
Then there's the guy that claims an additional 100 horsepower if the block, piston assys, cranks, etc get cryo'd. Nothing else mind you, just the cryo.......

Um, If I send that guy my WHOLE car, can he cryo my WHOLE car? Maybe sqeeze 150Hp out of it?
I mean cryo the whole dang car, tires, windshield wipers! Heck Cryo the Key too! I hear that Adds HP!!





(Note this is being satirical to the ridiculous notion)

[Alexander Chin]

"Then there's the guy that claims an additional 100 horsepower if the block, piston assys, cranks, etc get cryo'd. Nothing else mind you, just the cryo.......

Then there's the gun guy that will tell you how much more accurate and stable his gun barrels are after a cryo series........."


100 horses? Did he mean to say "cryo'd, nitro'd and overbored"?

There may be some basis for the improvement of accuracy in some rifle barrels. I've seen comparative articles where groups tightened considerably after cryogenic treatment. I don't recall the specific alloys, nor whether they were stainless or chrome-moly steels, but they were not 5160.

[Angus Trim]

Originally posted by Jeff Ellis
yes but if all is done right in the first place the cryo shouldnt be needed. right?

No Jeff, I wouldn't want to go there. The jury is still out about cryo...........

Just because it ain't likely for me, doesn't mean that it won't work wonders for someone else..........

Auld Dawg

[les yeich]

Originally posted by Jeff Ellis
yes but if all is done right in the first place the cryo shouldnt be needed. right?

i would say from my(a consumer's, not bladesmith) standpoint that is a pretty good summation.

[Wesley Pryor]

I know squat about sword making, but cryo treatments are used in the gun industry... and as I have many guns and like to keep up on the latest gun tech I'll pass along the following.

Cryo treatment is often done to gunbarrels to "increase" the accuracy potential of marginal barrels. (the stress relieving is said to help with the harmonic vibrations of the barrel as a bullet travels down it, or some other hocus pocus) And most treatments are sold with that claim. However minimal to non-existent benefits have been produced. These treatments are done on already hardened barrels.

But some Cryo treatments have produced noticeable results. The greatest benefit when cryo treating a barrel has been shown to be when the cryo treatment is done before any heat treating. The the benefits on barrel accuracy are more noticeable as compared to the same barrels that were'nt cryo treated before the heat treat.

But the steels used in the gun industry are different that the steels you mention so I don't have the slightest clue if cryo treating before heat treating would make any difference.

[Robert C]

The cryo nonsense is worse in the gun industry .Wild claims but the NRA and some of the best barrel makers found no benefit .Typical barrel steel is 4140. Today I found another bit of nonsense on the www.benelliusa.com . Their new shotgun has a cryo'd barrel and they show photos of the steel .One without cryo (pearlite structure) and one of their barrel with cryo( martensite) . Well cryo doesn't heat treat the steel, it only reduces retained austenite, which you wouldn't expect retained austenite anyway !! But for $50-75 they will cryo the barrel and make you happy. But the treatment won't be successful unless they say "abra cadabra, hocus pocus"

[Dave Hanks]

Robert you just have to have faith that the steel is alive and cyro unleashes the magic hidden inside...

I think I read something like that somewhere...

[Douglas S]

99% marketing hype...

[Karl Foster]

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