Po' man's cryo treatment questions

DeadboxHero

DeadboxHero

Knifemaker / Craftsman / Service Provider
Joined
Mar 22, 2014
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I take an O1 blade queched in peanut oil, tempered in a household oven for 45 minutes at 450°F then cooled to room temperature and placed in a household freezer would this crude and horrible way of doing things help remove retained austenite and improve sharpening, edge holding and toughness?

Please help. Or laugh hahaha
 
It's not cold enough. Dry ice in a slurry will get you closer to where you need to be for RA reduction.
 
Cold treatment for RA reduction needs to be a continuation of the quench.
 
What Russ said. I didn't catch that you were doing a full temper first. Quench and then into the dry ice.

-nathan
 
You will get some benefit from putting the blade in the freezer right after the quench, full benefit if you use dry ice or LN.

If you temper first, you will have stablized austenite and no change will take place.

Hoss
 
Awe, I see.

thanks everyone
Saved me a ton of time and money.

For dry Ice, I saw a technique done with rv coolant mixed with dry Ice in a bucket. Any thoughts?
 
I've tried the RV coolant (the pink stuff) and it froze on me.I went back to alcohol.
DeadboxHero said:
Awe, I see.

thanks everyone
Saved me a ton of time and money.

For dry Ice, I saw a technique done with rv coolant mixed with dry Ice in a bucket. Any thoughts?
Click to expand...
 
O-1 does not needs sub-zero treatment or cryo. The Mf is around 125°F.

Quench in canola or any medium speed quench oil warmed to 120°-140°F
Remove from oil after 15 seconds and straighten any warpage before it stiffens at 400°F
cool to room temp in still air ( hanging on a wire is best)
immediately temper twice at around 400°F for one hour each temper cycle
Water quench between and after tempers

This will give you a blade with little or no RA and a final hardness of Rc 60-61.

A home freezer will do nothing for O-1, and virtually nothing for any steel that does need sub-zero treatment to reach Mf.
The sub-zero part of the quench is nearly 100° lower than a home freezer....around -105°F
 
What Stacy just wrote is exactly how I heat treat my O1. I get very consistent results every time. I just did 2 in o1 and loosely documented them on my Instagram. You can see a short video of my heat treat setup and the Rc numbers directly after the quench, and then after the temper.

-Adam
 
Here's some info on O1 and retained austenite. Note heat treatments A,C, and D. Notice the reduction in RA quenching down to 68'f instead of 125'f. makes me think that there might be a benefit in going colder even if it's not to sub zero levels.

Hoss
 

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What the 68F is, is room temp....nothing special there. It shows quenching in room temp oil vs pulling out at 125F as being slightly better, which leads to my next comment. I would bet these are tests on a standard 1" round test rod, which is very different than knife thickness. The -321F is cryo, which is where a structural change happens. The range between 68F and -321F isn't a sliding scale where a bit more happens every so many degrees cooler. The conversion to martensite is done at room temp, and any RA is converted at -321F. Between the two, the percentage stays pretty much constant.

Additionally, these percentages of RA are not significant in knife blades (and knives quenched in oil almost surely have lower RA).

What is shown the most by these tests is that a lower austenitization temp is much better than over heating the blade. O-1 is a steel the needs a HT oven and good temp control to get the most out of it.
 
I started this thread because I wanted the maximum performance for a 3-5 inch blade in O1.

Heat treatment is the most important part of the knife
But my knowledge is low

I have a caveman setup.

Map touch
Stacked refractory bricks
And peanut oil in a 24 oz tall can.
With tempering in an oven.

I have three more questions now.

Are there any accurate cheap solutions for temp checking?
I've been going by the color of the steel.

Second, would wrapping the knife in foil help keep my temp more consistent in my home oven?

Lastly, is there no performance increases what so ever with cryo for O-1?
If so would dry ice with rv coolant in a bucket work?
 
DeadboxHero said:
I started this thread because I wanted the maximum performance for a 3-5 inch blade in O1.
Heat treatment is the most important part of the knife But my knowledge is low

I have a caveman setup.
Map touch
Stacked refractory bricks
And peanut oil in a 24 oz tall can.
With tempering in an oven.

I have three more questions now.

Are there any accurate cheap solutions for temp checking?
I've been going by the color of the steel.

Second, would wrapping the knife in foil help keep my temp more consistent in my home oven?

Lastly, is there no performance increases what so ever with cryo for O-1?
If so would dry ice with rv coolant in a bucket work?
Click to expand...



You have several things to deal with here. I highlighted the important things:

You know that HT is most of what makes a knife good or poor....you want top quality....You have minimal, bordering on poor, HT procedures and equipment....on a steel that requires a more precise HT. You can't have all those together.

O-1 should be done in a HT oven. It will harden with a torch and peanut oil, but it won't be near the quality of a 10-15 minute soak at 1455F (after a 1200F pre-heat) and a quench in Parks AAA.

Cryo is at -300F ( LN), a dry ice bath is at -100F, the Mf of O-1 is around room temperature ( or slightly above). Dry ice won't make any difference. Cryo will gain a few percentage less Ra and perhaps a point extra hardness. Use denatured alcohol with dry ice, not RV coolant. Use a rectangular metal pan, not a bucket.
 
This chart is for T1 so it may not apply to O1. It does show that both time and temperature affect how RA is converted.

One problem with eliminating RA is that most steels give up some toughness in doing so.

Lots of tool steels have RA.

With practice, you should be able to dial in a very good HT for your O1.

Hoss
 

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You guys are amazing. Thanks, I have lots of reading ahead of me.
 
Stacy E. Apelt - Bladesmith said:
O-1 does not needs sub-zero treatment or cryo. The Mf is around 125°F.

Quench in canola or any medium speed quench oil warmed to 120°-140°F
Remove from oil after 15 seconds and straighten any warpage before it stiffens at 400°F
cool to room temp in still air ( hanging on a wire is best)
immediately temper twice at around 400°F for one hour each temper cycle
Water quench between and after tempers

This will give you a blade with little or no RA and a final hardness of Rc 60-61.

A home freezer will do nothing for O-1, and virtually nothing for any steel that does need sub-zero treatment to reach Mf.
The sub-zero part of the quench is nearly 100° lower than a home freezer....around -105°F
Click to expand...

Thanks man, Im following this recipe.
 
Stacy, would this also work well for w1 tool steel from old Nicholson files?
 
W1 needs a faster quench than canola oil. The W in w1 stands for water. As in water quenching steel. Use water, brine, or if you have it, a fast quench oil.
 
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