How many steels need the cryo/dry ice phase of the heat treat process?

To help us dummies out, how about a yes or no to the following steels for benefitting from cryo. (I skipped the stainless because that was already talked about above)

D2
A2
M2
O1
W2
1095
1084
1070
5160
52100
 
D2--Yes,yes
A2--yes
M2--yes
O1--maybe
W2--no
1095--no
1084--no
1070--no
5160--no
52100--no

Stan
 
Get the mill johnny, im comfortable doing my own high carbons using the simple oxy/acet. setup, i havent done any cryo treatments....most of my stainless has gone to paul bos. I did make a nice jig that helps straighten warpage after h/t. I would love to have a little green grizzly benchtop mill to help me do guards!! I get the stink eye when i bring up making folders to certain people who are showing me the ropes! G Haile
 
I was just kidding.

Stan covered the high alloy steels.
W2, 1095, and 5210 may all gain a bit, since they are all hyper-eutectoid.
O-1 probably won't gain much, if anything.
 
GTH11 said:
Get the mill johnny, im comfortable doing my own high carbons using the simple oxy/acet. setup, i havent done any cryo treatments....most of my stainless has gone to paul bos. I did make a nice jig that helps straighten warpage after h/t. I would love to have a little green grizzly benchtop mill to help me do guards!! I get the stink eye when i bring up making folders to certain people who are showing me the ropes! G Haile
Click to expand...

Care to share a picture of that jig, G?
 
This is a great thread but I am still confused about a couple of points.

The sticky (on cryogenic treatment) suggest that for regular quenching of steels 50 - 95% of the austenite is converted to martensite. Cryogenic quenching results in near 100% conversion. Doesn't cryogenic treatment of even mild steels increase the martensite? The hardness of simple quenched 1048 with 99.9% martensite is HRC 60. 95% martensite in 1048 is HRC 57.

It also suggests that no harm is done to the steel in the treatment. For 52100 wear resistance increases by over 400%. Doesn't that indicate that 52100 would benefit from cryogenic treatment due to increased edge retention?
 
alb1k said:
Care to share a picture of that jig, G?
Click to expand...

I'll get him to do a shop tour thread including the jig.

I've been to his shop and where I've used money to set mine up, Greg has used a lot more ingenuity including a 2"x72" grinder built from _________ (to be revealed by Greg)....:D:D

Bo T said:
This is a great thread but I am still confused about a couple of points.

The sticky (on cryogenic treatment) suggest that for regular quenching of steels 50 - 95% of the austenite is converted to martensite. Cryogenic quenching results in near 100% conversion. Doesn't cryogenic treatment of even mild steels increase the martensite? The hardness of simple quenched 1048 with 99.9% martensite is HRC 60. 95% martensite in 1048 is HRC 57.

It also suggests that no harm is done to the steel in the treatment. For 52100 wear resistance increases by over 400%. Doesn't that indicate that 52100 would benefit from cryogenic treatment due to increased edge retention?
Click to expand...

Looks like it's time for me to go through the stickies again.... I hate to have Stacy and other knowledgeable people have to type out explanations all over again... Though, I greatly appreciate it when it's done...
 
Brian;

I pulled my information from a web publication by Linde gas. I think that I read and interpreted the sticky on cryogenic treatment correctly but ......


Bo Thomas
 
"wear resistance increase by 400% " ?? I'd like to see the details of that .Did Linde do it or one of the cryo companies ? Whil cryo will reduce RA and produce eta carbides 400% seems a bit much !
 
heres a pic of that jig alb1k, pretty simple lets you adjust to where you have some warpage. I did hear about a simple cryo one can do with dry ice and acetone, no -100s but i think-30s, not to sure! Im still building my confidence in my making techniques let alone trying to tackle and be confident in heat treating and all those variables, i like KNOWING i hit the rc on my blades, granted i have some access to a akron digital hardness tester, i think i would want one in my shop to have complete faith in my process?? Just my .02! And johnny get the mill...those jmac folders are screaming for a mill!!! Remember some of the best makers in the world outsource their h/t thats how important it is!!!!! G Haile
 

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GTH11 said:
heres a pic of that jig alb1k, pretty simple lets you adjust to where you have some warpage. I did hear about a simple cryo one can do with dry ice and acetone, no -100s but i think-30s, not to sure! Im still building my confidence in my making techniques let alone trying to tackle and be confident in heat treating and all those variables, i like KNOWING i hit the rc on my blades, granted i have some access to a akron digital hardness tester, i think i would want one in my shop to have complete faith in my process?? Just my .02! And johnny get the mill...those jmac folders are screaming for a mill!!! Remember some of the best makers in the world outsource their h/t thats how important it is!!!!! G Haile
Click to expand...

Very cool jig for straightening, thanks for the pic!

Thanks for the kind words on my folder project too!:thumbup: You make a good point about pros sending out for HT. It really is important and I'm feeling more comfortable about my decision to hold off for a little while longer while I learn more details.
 
Two questions: One, Crucible states on their info pages that the cryo or -100 treatment is done AFTER the first temper- Bladsmth's post makes me think that it makes a huge amount of sense to send it right on down to Antarctica as part of the quench, since conversion to martensite is what we're trying to accomplish why would it be helpful to interrupt the cooling curve by taking it only to room temp. and oven tempering?

Two: Do any of the kool kids use 440c anymore? CPM 154 is better, but not dramatically better- is it enough better that 440c is obsolete?
Thanks
Andy G.
 
I go straight from plate quench to cryo,leave them overnight then take them out in the AM,as soon as they reach room temp.they go in the temper oven for 2 cycles.
Stan
 
mete said:
"wear resistance increase by 400% " ?? I'd like to see the details of that .Did Linde do it or one of the cryo companies ? Whil cryo will reduce RA and produce eta carbides 400% seems a bit much !
Click to expand...

I tracked down the reference; R.F. Barton, "How Cryogenic Treatment Controls Wear". It states that the steels tested received conventional heat treatment, cold treatment, and cryogenic treatment. Rw for untreated 52100 was 25.2 and oops.... cryogenic treated 52100 had a Rw of 135. Meaning over a 500% increase in wear resistance. 5 steels were tested; 52100, D2, A2, M2, and O1. They all showed fairly dramatic results.
I don't know the final RHC for the tests.
 
GTH11 said:
heres a pic of that jig alb1k, pretty simple lets you adjust to where you have some warpage. I did hear about a simple cryo one can do with dry ice and acetone, no -100s but i think-30s, not to sure! Im still building my confidence in my making techniques let alone trying to tackle and be confident in heat treating and all those variables, i like KNOWING i hit the rc on my blades, granted i have some access to a akron digital hardness tester, i think i would want one in my shop to have complete faith in my process?? Just my .02! And johnny get the mill...those jmac folders are screaming for a mill!!! Remember some of the best makers in the world outsource their h/t thats how important it is!!!!! G Haile
Click to expand...

Thanks, G!

I have a fat blade that got a bit of warp. I may try something similar. I appreciate the follow -up!

Erik
 
There is some risk when going from quench directly to cryo therefore the recommendations to temper before cryo. HOWEVER it should be a "snap temper" at 300 F. At higher temperatures the tempering stabilizes the retained austenite .There does not seem to be a significant risk among the knifemakers here.

Straightening -- if the blade has been hardened don't try straigthening below 400 F ,very risky !

Bo T., That's R.F.Barron and the paper is from 1982. If you have a link from the paper please post it.
In 1982 they didn't understand the formation of eta carbide which is the strengthening and hardening mechanism.
 
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Bo T said:
This is a great thread but I am still confused about a couple of points.

The sticky (on cryogenic treatment) suggest that for regular quenching of steels 50 - 95% of the austenite is converted to martensite. Cryogenic quenching results in near 100% conversion. Doesn't cryogenic treatment of even mild steels increase the martensite? The hardness of simple quenched 1048 with 99.9% martensite is HRC 60. 95% martensite in 1048 is HRC 57.

It also suggests that no harm is done to the steel in the treatment. For 52100 wear resistance increases by over 400%. Doesn't that indicate that 52100 would benefit from cryogenic treatment due to increased edge retention?
Click to expand...

The Mf (martinsite finish) temperature is a moving target. Complete conversion of martinsite is dependent on alloy content and highly dependent on carbon content specifically. The more carbon, the lower the Mf temperature. Mild steels and steels in the 1040 class have a higher Mf temperature and may not need sub-zero temperatures to complete the transformation. Add a bunch of elements like nickel, chromium, molybdenum, etc. and maybe they do. It pays to know the steel you're dealing with, as in this example it's the difference between 1040 and 4340 alloy steel.
 
"Bo T., That's R.F.Barron and the paper is from 1982. If you have a link from the paper please post it.
In 1982 they didn't understand the formation of eta carbide which is the strengthening and hardening mechanism.

I am looking at 2 papers from Linde. Barron's research was referenced from a conference in Shreveport in 1982 but the citation with the table of information comes from 1973, Louisiana Tech University. A more recent citation from the Linde web paper gives a 420% increase in wear resistance for 52100 and cites P Paulin, Gear Technology, March/April 1993, p.23.
 
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