Stainless Heat Treat w/o Cryo?

J

John L

Joined
Oct 28, 2004
Messages
1,330
Is there a good stainless alloy that heat treats well without a cryo stage? Would like to HT in my Evenheat and not send out for cryo. thanks
 
There are and have been many stainless knives made and used without Cryogenic treatment between hardening and tempering. It is a process that refines the grain structure by a more complete martensite transition. I will let the professors around here explain it in more detail. I use it sometimes, but for the most part, I do multiple tempers and get good results out of ATS-34, 154CM and CPM154CM. I don't know how well it would work to harden, send out to be cryogenic treated and then come back to be tempered. I don't like the delay there between the steps. Just my opinion.
Jim
 
Hi John

Most stainless are just fine w/o cryo. It does make a difference - but the difference is way out on the edge of performance. I doubt the average user would know the difference - except in the intrinsic way of knowing that the heat treatment process was the best it could be.

Sending blades out for cryo is not the best solution. It should be done either immediately after hardening or immediately after the first temper.

my 2 cents

Rob!
 
What Rob and Jim said is basically the story.
440C will do fine without cryo,so will ATS-34,and the new CPM154.
What the cryo will give you is about 2 points Rc over non-cryo.
As Rob said, most users will not be able to tell Rc58 from Rc60.

OT,but related -
I had a visit from Kerrie Kengor,the rep from Crucible Steel Monday.Nice lady.She is going to be getting some technical info for me on the CPM 154.What she had so far from the lab boys is that it works and Heat Treats the same as the old stuff.The polish is better,and as far as knives go,the edge should be better.
We discussed the nomenclature,which is still confusing.Sometimes it is labeled CPM154CM others CPM154.The older,non-particle process ,steel is still 154CM.She thinks they will start using CPM154 as the new name.
I am working with Crucible on a test project to do a comparison on O-1 vs CPM154 vs CPM125V. The results will be released in an article for one of the magazines,and ,of course,here on the BF.
Stacy
 
bladsmth, thanks for doing this, what is the chance of adding ATS-34 into the mix? I know, I know if you add the steel I'm interested in for comparison...you will have to add a 100 more. Can't blame me for asking.
 
Cryo does NOT refine grain !! It will make the Martensite conversion more complete and add up to 2 points in Rc hardness....Unless they decide to add a bit of vanadium 154CM and CPM154 are the same chemically but the manufacturing process offers advantages .The CPM method gives finer and more evenly distributed carbides.This makes it easier for the blade maker to grind and polish and a tougher blade ,easier to sharpen and better performance for the blade user.
 
Thank you mete for correcting me. I had been told that as the Martesite completed its conversion that it refined the grain. Glad to know the facts. Sorry for any confusion I may have caused. This is a great site and resource.
God Bless!
 
just my 2 cent only here..and food for thought

depending your heat treat effectiveness your cryo can benefit the steel up to and over 30%
,,,you tell me if you should or not:confused: :D

I won't do any SS with out it.. I also do it in house..
just my Opinion :) the cost versus possible advantage out weighs me doing it any other way..
the end user just might know something about knives..and some of them are on these forums..:)

It's like a carpenter that out smarts himself cutting corners thinking no one will know the difference in his work if it's sloppy because he's the carpenter..

do what's right for your further possible RE-peat customer. you'll thank yourself later..and feel you've done your best..
if you can't do it,, be up front with the customer with why you can't or won't do it..the web makes this a very small world..and it is your own rep you're playing with.
 
Stag & Steel - ATS-34 is the same thing as 154CM.The CPM154 is 154CM made by the particle metal process.It is finer grained and polishes better.You will like it a lot if you like ATS-34.
Stacy
 
All my blades get the cryo treatment. I am really looking forward to Stacy's experiment and results. I think it is a really great idea, Stacy. Any time frame on when you are going to task that?
 
Deep cryo rules. You have already spent more for your Even Heat than you can get a decent dewar for. If you want to do the complex steels get a dewar too. Why go half way(?). Being honest though, it took me some months to save up for a dewar after I had gotten my Even Heat and was treating stainless without deep cryo during that time (used dry ice instead - sucks). I did have the dewar way high on my list of toys to get though.

Roger
-----
 
Speaking of Cryo: Is there a recommended Dewar model/size that works well for knifemaking?

Thanks,

George
 
gspam1 said:
Speaking of Cryo: Is there a recommended Dewar model/size that works well for knifemaking?

Thanks,

George
Click to expand...

mine is a Lab Dewar
and the TW is about 8.5 lbs and it cost me just over $10.00 to fill it
the LN will last about 24 hours in it, which I like because it will give a slow warm up with-out removing the blades..
I should get one that will keep the LN for a long time but this works well for me , I got it from Ebay I think it cost me like $175.00 at the time.
 
Dan Gray said:
mine is a Lab Dewar
and the TW is about 8.5 lbs and it cost me just over $10.00 to fill it
the LN will last about 24 hours in it, which I like because it will give a slow warm up with-out removing the blades..
I should get one that will keep the LN for a long time but this works well for me , I got it from Ebay I think it cost me like $175.00 at the time.
Click to expand...
that sound about the way i need to go can you link me some specs
 
mete said:
Cryo does NOT refine grain !! It will make the Martensite conversion more complete and add up to 2 points in Rc hardness....Unless they decide to add a bit of vanadium 154CM and CPM154 are the same chemically but the manufacturing process offers advantages .The CPM method gives finer and more evenly distributed carbides.This makes it easier for the blade maker to grind and polish and a tougher blade ,easier to sharpen and better performance for the blade user.
Click to expand...
Mete does that means timing is not an issue ? I could get cyro-benefits
any time prior to final assembly ??
Thanks
 
Timing IS critical. Harden,cryo immediately,[snap temper first at 300-350 F to reduce risk ] temper twice , two hours each. Cryo does nothing significant after temper !!
 
butcher_block said:
that sound about the way i need to go can you link me some specs
Click to expand...
specs ? Butch what do you mean?
TW is about 8.5 lbs
Click to expand...
Tear weight if the spelling is right
mine holds 8.5 lb's of LN. this is a small one..
is that what you mean?
 
You'll probably want to go on the lower end of austenitizing temperatures, and do a double or triple temper. You might want to test heat treatment at a couple different austenitizing temperatures to find the best hardness without cryo if you have a Rockwell tester.
 
opening size and depth
if i was to do 12 inch or larger blades
i work with mostly cpm steels so i know im missing out on some by not freezing
butch
 
If you are looking for a dewar, ask around the various gas companies, if they will sell you liquid nitrogen, they may have or be able to get dewars as well. One of the places I spoke with in the past was willing to lease out the dewars for about $15-$20 a year, just to keep me coming to them for the nitrogen.

Ken Nelson
 
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