Is Cryo Really Neccesary?

[mete]

Do some searching of our forum,
Subzero reduces RA
Cryo Reduces RA + permites formation of eta carbides

 

[Matt Rochester]

I have used 440c without subzero. I did put it in the freezer after plate quenching. I don't know if it did anything or not but it tested around 59RC. I have some cpm154 and will be doing a subzero bath for it. I can get dry ice pretty cheap from a local Publix so, why not?

As far as steels go, I was considering 440C, AST34, 154CM, and maybe some AEB-L or CMP154 at some point.

 

[elementfe]

Do some searching of our forum,
Subzero reduces RA
Cryo Reduces RA + permites formation of eta carbides

METE, would you expect a 30% difference between subzero (dry ice) and cryo?
Cryo has been usually characterized as "maybe making a small difference" vs subzero.

 

[BenR.T.]

If you are making the knives to sell, I believe you should get the most out of the steel you choose to use. If you can't do a proper HT (which includes LN Cryo for some steel), either use a different steel or have a professional HT shop do them for you. I see no other reason than being cheap, to not get a dewar and do an LN soak on the steel that needs it. Just my opinion.

 

[SBuzek]

If you are making the knives to sell, I believe you should get the most out of the steel you choose to use. If you can't do a proper HT (which includes LN Cryo for some steel), either use a different steel or have a professional HT shop do them for you. I see no other reason than being cheap, to not get a dewar and do an LN soak on the steel that needs it. Just my opinion.

Bingo

 

[Rhinoknives1]

Short answer, no. If you can't cryo, go ahead anyway. The difference is so small it's almost impossible to detect in everyday performance, i.e., skinning game, whittling, cutting paper, etc., etc.. Under a microscope, yes, you see a difference.

Many knives made here and around the world out of stainless are without Cryo and save people just fine. All that said, I have ALL of my stainless steels Cyroed by Buck knives and every little bit I can do to make a better preforming and comfortable knife,is going to happen on my knives!

Darn, that's basically what I said. Can I undelete my post?

Patrice, As my wife says to me, I still love you!

Some steels get a huge benefit from cryo. The Uddeholm metallurgist told me AEB-L gains up to 30% better edge holding from cryo.

Chuck

As far as steels go, I was considering 440C, AST34, 154CM, and maybe some AEB-L or CMP154 at some point.

I have used or currently use 440C CPM-154 & AEB-L and can tell you they all will benefit from Cryo.

I'm not doubting cryo makes a difference, what I am doubting is if it makes enough of a difference for the average guy, doing average knife things, to notice a difference. I didn't, I skinned deer, cut rope, etc., with cryo'ed knives, and with others that were not. I didn't abuse the knives, just used them, I'm sorry, but I could not tell any difference at all. None of them, by the way, were AEB-L.

I wish to make knives for the discriminating User/Collector so I have my steels Cryo treated.

 

[jdm61]

A dewar is expensive. Sending out your knives that should have cold treatment is fairly cheap unless you only send a couple at a time. Last time I checked, Peter's base charge was $100 for up to 20 of the same or SIMILAR steel, similar meaning that the austenizing temp was the same. I send 12 CPM3V blades and was able to sneak in 8 made from AEB-L because the austenizing temp is the same for both. No charge for the different tempering temps. Thats $5 a blade plus shipping.

 

[DukeHarley]

I have not used stainless yet but my opinion is if the customer is paying for a steel that benefits from a subzero or cryo then I'd owe it to the customer to get the maximum performance out of the chosen steel weather they are an average joe who won't know the difference or a decerning knife collector.

 

[David Stifle]

Well, as I said, fellas, I've used both cryo'ed and non-cryo'ed blades, and I couldn't tell the difference at all. Both sharpened nicely, both held an edge equally well, and both performed the same as far as I could tell. With that said, I do send most of my blades to a Ht house, where they cryo them as the steel requires. It's a nice to do thing, can't hurt, but still don't really think it makes all that much difference.

 

[elementfe]

Til someone publishes test results, Subzero Si, Cryo Meh.

 

[Lo/Rez]

I would agree with that.

 

[DukeHarley]

It is used in industry to treat tool steels (both trim steels and punches) for the tool and die trade. Cant imagine these big companies are spending the resources if there wasnt some published data supporting it. Just a thought!

Jay

 

[samuraistuart]

The way I see it (always lots of opinions and thoughts on cryo and sub zero)....

If it is a stainless steel (from AEB-L all the way to CPMS90V or the latest/greatest)....you should be doing AT LEAST a sub zero in order to reach as close to Mf as you can. If working with the high alloy stainless.....going full on cryo may not give a super noticeable improvement in performance....but there are some things going on there, and during tempering afterwards, that would warrant it.....IF you are trying to make the best blade that you can. If you spend all that money and time working that alloy...why not get the most out of it?

If it is carbon steel.....full on cryo probably is not needed in ANY case. But what about sub zero? That depends on carbon/alloy content and how you heat treated it. If you're shooting for minimal carbon in solution to attain max hardness, leaving the rest as carbide....then sub zero likely won't be doing much at all. But if you want to put more carbon in solution, like most all the carbon in White Steel, this will drop Ms and Mf, in which case sub zero might be called for to reach theoretical Mf.

 

[elementfe]

My mind is totally open on this subject, would love to see test results showing marked improvement cryo vs subzero.
LN would be a much simpler and more controlled process than dry ice in a large shop or industrial setting, so I'd expect them to use it for that reason at least.
I'd have to travel a lot farther for it than the corner grocery store, though, and buy equipment to make it feasible.

 

[mete]

ElementFe, cryo gives 1-2 HRc higher hardness and many makers here say they do notice the difference in use !!

 

[BluntCut MetalWorks]

Check (& scrutinize away) this study - http://www.cryogenictreatmentdatabase.org/article/sub-zero_treatment_of_steels/

Excerpt table from the pdf


Be warn: for some steels and/or/with intended-use cryo or sub-zero treatment could be counter productive because of lean RA and dimensional distortion.

 

[samuraistuart]

I've seen that chart, or one similar. 400% increase in wear resistance with O1 and 52100? Well, I used to think "wear resistance" was the thing to look at with edge retention. USED TO. But even then, 400% increase seems improbable.

And the Ms Mf chart given in the link brings me back to where I was on the thread at Hypefree.....confused because two charts on Mf give totally different readings. That chart shows Mf of our carbon steels to be around -100f. Which flies in the face of what I have always heard and seen in other charts....that Mf is above or around room temp.

But I am like Sgt Schultz when it comes to this topic....."I know nothing, I was not even here, I did not even get out of bed this morning".

Thanks for the link Mr La. I think the subject of subzero/cryo treating steels is cool. Oh I did not just say that.

 

[David Stifle]

ElementFe, cryo gives 1-2 HRc higher hardness and many makers here say they do notice the difference in use !!

Expectations, my friend. If you expect something to be better, that's more than likely the conclusion you will reach.

 

[BluntCut MetalWorks]

Yup, #s are no-doubt well-massaged inflated marketing lit:barf: however the idea of cooling below Mf is cool, it's valid concept worthwhile study/reading. Lately my Dewar stays empty because with my metal tinkering (a bunch of carbon steels) there is not readily detectable benefit from Cryo for edge wear & stability. otoh, I will refill my dewar for cryoing high Cr steels <= RA should be below 15%, otherwise edge will easily roll or fracture (from untempered brittle martensite converted by impact, also work-hardening doesn't works well in high alloy steels).

I've seen that chart, or one similar. 400% increase in wear resistance with O1 and 52100? Well, I used to think "wear resistance" was the thing to look at with edge retention. USED TO. But even then, 400% increase seems improbable.

And the Ms Mf chart given in the link brings me back to where I was on the thread at Hypefree.....confused because two charts on Mf give totally different readings. That chart shows Mf of our carbon steels to be around -100f. Which flies in the face of what I have always heard and seen in other charts....that Mf is above or around room temp.

But I am like Sgt Schultz when it comes to this topic....."I know nothing, I was not even here, I did not even get out of bed this morning".

Thanks for the link Mr La. I think the subject of subzero/cryo treating steels is cool. Oh I did not just say that.

 

[jdm61]

I have seen a maker of CRAZY expensive folders heat treat S90V without cryo. When I think of steels that NEED cold treatment, ridiculously highly alloyed steels like that come to mind straight away. I thought that my head was going to explode when I saw that.