CPM Cru-Wear heat treat

Stacy E. Apelt - Bladesmith

ilmarinen - MODERATOR
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I cut my blanks before I heat treat Right? Also with the cryo can I use dry ice and isopropyl alcohol. Or just liquid nitrogen. How long after plate quench should I cryo. And how long after cryo do I double temper. Should I just wait till knife is cool to the touch. Thanks again for the help will send pics when it's done
 

Stacy E. Apelt - Bladesmith

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OK.
1) The heat treatment quench is referred to as a Continuous Cooling Curve. The cooling events should be done as a continuous set of steps with as little time between them as possible. aLso, avoid and steps that raise the temperature along the way.
2) Cryo treatment is done with liquified gasses at cryogenic temperatures in the range below -300°F. Sub-zero treatment is done at -100°F using a special laboratory freezer or dry ice and alcohol. The sub-zero temperature is the Mf for the cooling curve. Cryo will make some changes in the structures and lower Ra as well as increase hardness,
3) Tempering in Cru-wear can be at lower range of 400°F or the upper range of 1000°F. If cryo is not available, use the upper tempering range.
4) Tempering needs to follow the warm-up from the Mf as soon and smoothly as possible. It is best to allow the blade to warm to room temperature and immediately place in the pre-heated tempering oven. The second temper can be delayed overnight if necessary.

There is a more detailed discussion in the other Cru-wear HT thread.
 
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How long after the plate quench or at what temp do I let the knife get to before cryo. Can I use dry ice and isopropyl alcohol or should I use liquid nitrogen. After the cryo do I just wait until the knife gets back to room temperature before before the final 2 tempers. And again with the tempers do I let the knife return to room temperature before starting the next one or should I use the plates again. All the advice is greatly appreciated. It's my first time doing a heat treat. Thanks
 

Stacy E. Apelt - Bladesmith

ilmarinen - MODERATOR
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As said in the previous post,
Cryo is done in liquid nitrogen at -312°F
Sub-Zero treatment is done in dry Ice and alcohol at -100°F.
These are different processes, and either one will take the blade to the Mf point. Cryo does some other things that increase the hardness a tad.
Cryo is the better process but requires an LN dewar. Sub-zero will work fine if you don't have access to LN..

Once the blade comes out of the plate quench you can cool it to room temperature in running water or let it air cool to ambient. From there you can put it directly in the cryo or sub-zero bath.

The warmup from either is done by letting the blade warm to ambient room temperature and then immediately tempering.
 
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As said in the previous post,
Cryo is done in liquid nitrogen at -312°F
Sub-Zero treatment is done in dry Ice and alcohol at -100°F.
These are different processes, and either one will take the blade to the Mf point. Cryo does some other things that increase the hardness a tad.
Cryo is the better process but requires an LN dewar. Sub-zero will work fine if you don't have access to LN..

Once the blade comes out of the plate quench you can cool it to room temperature in running water or let it air cool to ambient. From there you can put it directly in the cryo or sub-zero bath.

The warmup from either is done by letting the blade warm to ambient room temperature and then immediately tempering.
I don’t have easy access to dry ice or LN. Could the heat treat process be adjusted to skip cold treatment or would a deep freeze be sufficient in some way?
 
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I don’t have easy access to dry ice or LN. Could the heat treat process be adjusted to skip cold treatment or would a deep freeze be sufficient in some way?
Have you looked at data sheet for CPM Cruwear? https://nsm-ny.com/products/nsm-data-sheets/

Industrial standard heat treat is no cold treatment but a high temper which takes care of RA.

While I now prefer a low temper cryo heat treat I have made hundreds of Cruwear knives using a 1950 oven, 30 minute soak, plate quench, and 1000 degree temper for 2 hours performed 2 times. This gives a hardenss around 60 Rc. If you want higher hardenss you can drop tempering temperature down to 950 according to the data sheet.
 
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Have you looked at data sheet for CPM Cruwear? https://nsm-ny.com/products/nsm-data-sheets/

Industrial standard heat treat is no cold treatment but a high temper which takes care of RA.

While I now prefer a low temper cryo heat treat I have made hundreds of Cruwear knives using a 1950 oven, 30 minute soak, plate quench, and 1000 degree temper for 2 hours performed 2 times. This gives a hardenss around 60 Rc. If you want higher hardenss you can drop tempering temperature down to 950 according to the data sheet.
I haven’t checked the data sheets yet, but I will now. Thank you
 
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