Liquid Nitrogen Treatment Questions

7

7HillsBlade

Joined
Jul 21, 2016
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I have searched around for cryo and LN answers, and haven't found what I was looking for. I am going to utilize this process during the HT of my blades. I will only be doing one blade at a time right now. Just getting started. My questions are:

1. How much LN do you usually buy and how long does it last? 10L, 20L, etc.

2. What type of container do you use to treat your knives with the LN? (do you just use the container the LN is in, or do you have a separate container you use for when treating a blade)

3. How are the blades sitting in the LN? Suspended, etc..

4. How long are you treating the blade? I have seen overnight, and as quick as 30 min. I have CPM-3V at .190 thick.

5. Do you treat it more than once? I have seen multiple and just once.

Thanks guys!!!
 
Cryo is not cost efficient for a one blade at a time shop.

The LN dewar is usually 10 or 20 liters. It lasts a month or two.

You hang the blade in the dewar on a wire or rod.

Leave it in the LN for at least an hour, up to overnight.

You do the cryo immediately after the quench and cooling to room temp. Some folks do a snap temper at 300F for 30 minutes to avoid any cracks, but most find it necessary. Temper twice after the blade warms up to room temp. There is not gain to doing a second cryo between tempers.


If doing just a blade at a time, you would be better of to send them out. Actually, if doing a lot of blades at a time you are also better to send them out.
While doing stainless and tool steels HT at home may be fun, the best results are almost always attained by the professionals who have much better equipment.
 
Thanks Stacy. I may take your advice and start off sending blades out, but ultimate goal is to become skilled enough to do everything in house, even if it means a little more cost. Just my personal preference. Want to be able to say I built the knife from start to finish.
 
yep need to do at least 20 per tank to mak eit worth it depending on how much you are being charged
i have a 20l big mouth tank and i shoot for 40 blades in a few HTs to make the cost work out
liek was said quench to room temp and then into the LN ( i suspend the blades over night) this gives the kiln time to cool slowly addig life to it. in the morning i start the kiln an dpull the blades from the LN so the blades come up to room temp and about the same time the kiln gets stable at 400f
 
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