Cryo quenching

Ken, I have no idea right now how much LN costs here. I need to call tomorrow and report back. Thanks!

My issue is that I did not remember that Type K read that low. I have a variety of them here, from coated fused-bead wire to 18" long 1/4", 3/8" and ceramic encased Inconel probes from experiments probing the inside of my forge and furnaces to see what the chaos was like inside. (Vertical forge kicks butt for even temps on any given plane, BTW. Great for welding.)

I thank you for telling me! Like you did, I'll be checking next time.
 
Is that 112 miles round trip? Or one way? $2.43/liter isn't all that bad. Each time I got to fill up I worry it won't be the same 50¢/liter it has been in the past. That makes 60 mile round trip not bad at all
 
KenH said:
Is that 112 miles round trip? Or one way? $2.43/liter isn't all that bad. Each time I got to fill up I worry it won't be the same 50¢/liter it has been in the past. That makes 60 mile round trip not bad at all
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one way....I make sure I have a bunch to do...lol.
 
Well, I called Airgas. Back when I last bought LN, the place was called Waukegan Welding and I got the stuff in my Dewar at a bit under a buck a gallon. I just got off the phone. These yayhoos want $131 to put 15L of LN in my Dewar. Plus tax, of course.

I'll find dry ice.
 
Dry Ice is just as effective as LN, after all a DI solution will hit the "magic" -95F required for full RA conversion. Boy, they're proud of their LN - that's almost $10/liter.... well, actually $8.73/liter.
 
I was astounded, Ken. What's even more aggravating is the plant that produces this stuff is less than 25 miles away. This is simple gouging. or, the guy made a big mistake calculating the price; it took him a while.

I found dry ice in the next town over. It'll be better for my one-blade-at-a-time/many months adventure anyway. I've been told the trip from -108F to -320F reduces austenite a bit more in some of these high alloys but nearly all is finished by -108, so DI will be plenty good for my needs.

I didn't calculate it out earlier - $8.73/L you say. Darned proud of it they are, for sure. Jeesh.
 
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fitzo said:
I was astounded, Ken. What's even more aggravating is the plant that produces this stuff is less than 25 miles away. This is simple gouging. or, the guy made a big mistake calculating the price; it took him a while.

I found dry ice in the next town over. It'll be better for my one-blade-at-a-time/many months adventure anyway. I've been told the trip from -108F to -320F reduces austenite a bit more in some of these high alloys but nearly all is finished by -108, so DI will be plenty good for my needs.

I didn't calculate it out earlier - $8.73/L you say. Darned proud of it they are, for sure. Jeesh.
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Mike...maybe give them a call back and just ask if it was a mistake? That wouldn't be the first knuckle-head you've run into....lol?
 
Smallshop said:
Mike...maybe give them a call back and just ask if it was a mistake? That wouldn't be the first knuckle-head you've run into....lol?
Click to expand...

I agree, Ted. He messed around so long calculating the price, I wonder. I asked him, "Really?" and he responded in the affirmative, so I let it go initially. I'm a ways away from having a blade to HT, so I will go in person and ask for a double check. Unfortunately, it will get me right next to their Miller welders. LOL

It'll be a lot easier in the long run to just haul a brick of dry ice downstairs rather than hump that Dewar down the stairs.
 
I use Dry Ice 5 bucks a pound with a 3lb minimum. Sometimes I post the need for DI on my Facebook page and get it from people for free when they order food from some of the Mail order food companies. I usually only do 4 blades at a time so I can stay in the window for the soak in my H/T oven etc...
 
There is *a lot* to chew on in this thread. I expect Kevin Cashen to jump in any minute to clear this all up but until then…
in No order:

I cryo after plate quench before any temper. I let the blade cool to room temperature, hang it from a wire and drop it to rest on the bottom of the tank overnight. I go for 8 hours (more won’t hurt) but have done as little as an hour. The amount of heat you put in your dewar from the blade mass is the same dunking it vs hanging in the chamber not in contact with the liquid.

We buy it every 8 -10 weeks at the same place and every time we pay a different price. This has happened at two different gas supply places. They really don’t know what to charge. Lately we have been paying around $50 for approximately 25 liters.

we use a 30 liter dewar with a piece of rolled up foam for the cork. The gas supplier can never get it full as it boils and smokes and they don’t like doing it so we get around 25 liters. We don’t really know.

we built a big foam insulated box to hold the dewar and doubled how long it lasts. I can’t recommend this enough.

It is required that you freeze stuff like a banana in it at least once.

I have tested (RC hardness) low alloy carbon steels in cryo and found no significant difference in hardness. I do not cryo carbon steel anymore.

I have tested doing a cryo after full temper and found almost no change in RC hardness.

If I have done my quench properly, I expect 1.5RC hardness increase from the cryo. I have seen it as low as .75RC increase to as much as 2.5RC. I considered the 2.5RC increase due to a poor quench when I tried to cut some foil and was too slow. I scrapped that knife. I also do not try and remove foil anymore as I plate quench everything - air hardening stuff I mean.

wear glasses but if you spill some on you, it won’t hurt or burn you.

dry ice, from what I recall was nearly as good in martinsite conversion.

For treating with dry ice, RV Antifreeze is pet safe, non toxic, non flammable, is significantly cheaper and won’t evaporate like acetone does. I can not understand why people still use acetone. I guess it’s because acetone doesn’t seem to freeze. RV antifreeze does turn to slush but the temperature is still the same. Liquid acetone in Dry ice does not get colder than slushy RV antifreeze in dry ice.

A very simple foam cooler with 2lbs of dry ice overnight will do a couple blades.

Laren Thomas wrote an excellent article on knife cryo with testing. He found even putting a blade blank in a home freezer overnight made a difference in RC. I am drawing a blank on his Patreon website if someone could post a link of his cryo article that would be cool.
(cool snicker)
 
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<<<<< mois laboratorydog. old laboratory dog, BossDog .

I like acetone. Nothing wrong with antifreeze, either, provided, of course, the newly implemented propylene glycol bath/dry ice doesn't end up unexplained in the flask of $20,000 worth of freeze-dried experimental drug. Oops. Back to acetone. Long story.

Your case poses no reason not to change, Tracy, and instead a great case. But in this case, at least, you know what they say about the old dog...

Be well, my friend. :)


BossDog said:
.....

For treating with dry ice, RV Antifreeze is pet safe, non toxic, non flammable, is significantly cheaper and won’t evaporate like acetone does. I can not understand why people still use acetone. I guess it’s because acetone doesn’t seem to freeze. RV antifreeze does turn to slush but the temperature is still the same. Liquid acetone in Dry ice does not get colder than slushy RV antifreeze in dry ice.

.....
Click to expand...
 
Doug Lester said:
At the risk of looking like a smart ass (my ex-wives would agree that that's one of my strong points) may I ask what steel you are treating. With something like 1075 all you are going to do is make your steel real cold with no real benefit for the molecular structure of the steel. Some of you high alloy steels need it for peak performance. Just saying that before you spend time and money on the dewar and liquid nitrogen, make sure that you need them.

Doug
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Sure thing I am using Nitro-V and I have some D2 I've been needing to treat too. And I have been giving (in a sense) a Dewar I just had to pay the money to fill it.
 
Guin, have you found a place to fill your dewar with LN yet? If so, what price are they quoting?
 
BossDog said:
There is *a lot* to chew on in this thread. I expect Kevin Cashen to jump in any minute to clear this all up but until then…
in No order:

I cryo after plate quench before any temper. I let the blade cool to room temperature, hang it from a wire and drop it to rest on the bottom of the tank overnight. I go for 8 hours (more won’t hurt) but have done as little as an hour. The amount of heat you put in your dewar from the blade mass is the same dunking it vs hanging in the chamber not in contact with the liquid.

We buy it every 8 -10 weeks at the same place and every time we pay a different price. This has happened at two different gas supply places. They really don’t know what to charge. Lately we have been paying around $50 for approximately 25 liters.

we use a 30 liter dewar with a piece of rolled up foam for the cork. The gas supplier can never get it full as it boils and smokes and they don’t like doing it so we get around 25 liters. We don’t really know.

we built a big foam insulated box to hold the dewar and doubled how long it lasts. I can’t recommend this enough.

It is required that you freeze stuff like a banana in it at least once.

I have tested (RC hardness) low alloy carbon steels in cryo and found no significant difference in hardness. I do not cryo carbon steel anymore.

I have tested doing a cryo after full temper and found almost no change in RC hardness.

If I have done my quench properly, I expect 1.5RC hardness increase from the cryo. I have seen it as low as .75RC increase to as much as 2.5RC. I considered the 2.5RC increase due to a poor quench when I tried to cut some foil and was too slow. I scrapped that knife. I also do not try and remove foil anymore as I plate quench everything - air hardening stuff I mean.

wear glasses but if you spill some on you, it won’t hurt or burn you.

dry ice, from what I recall was nearly as good in martinsite conversion.

For treating with dry ice, RV Antifreeze is pet safe, non toxic, non flammable, is significantly cheaper and won’t evaporate like acetone does. I can not understand why people still use acetone. I guess it’s because acetone doesn’t seem to freeze. RV antifreeze does turn to slush but the temperature is still the same. Liquid acetone in Dry ice does not get colder than slushy RV antifreeze in dry ice.

A very simple foam cooler with 2lbs of dry ice overnight will do a couple blades.

Laren Thomas wrote an excellent article on knife cryo with testing. He found even putting a blade blank in a home freezer overnight made a difference in RC. I am drawing a blank on his Patreon website if someone could post a link of his cryo article that would be cool.
(cool snicker)
Click to expand...
Post of the month.
 
fitzo said:
<<<<< mois laboratorydog. old laboratory dog, BossDog .

I like acetone. Nothing wrong with antifreeze, either, provided, of course, the newly implemented propylene glycol bath/dry ice doesn't end up unexplained in the flask of $20,000 worth of freeze-dried experimental drug. Oops. Back to acetone. Long story.

Your case poses no reason not to change, Tracy, and instead a great case. But in this case, at least, you know what they say about the old dog...

Be well, my friend. :)
Click to expand...

You are a professional chemist and clearly understand the dangers of acetone. Many beginners do not.
You probably bleed acetone.
 
BossDog said:
You are a professional chemist and clearly understand the dangers of acetone. Many beginners do not.
You probably bleed acetone.
Click to expand...

We all exhale a tiny bit of acetone, as our bodies make it. It's far less toxic than people think, but that flammability hazard even when cold justifies your suggestion to switch to propylene glycol, Tracy.

I'm still interested in that polymer stuff they sell for mixing water-based quenchants with times suitable for 1095 all the way to slow steels like stainlesses all by controlling concentration of the solution. That'd allow me to do plain steels in the basement again, sans quench oil stench.
 
I just got 2 gallon of Parks 50 from Boss, how much smell is that going to have quenching in the 1500F range?
 
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