Heat Treat without Cryo, what to expect?

Dirk

Dirk

Joined
Mar 19, 1999
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I used to do most all heat treat in my shop without cryo. I used 154cm, D2, and S30V with good results. I started sending heat treat out as I was spending a lot of time doing heat treat on larger orders. Last year I decided I needed to get back to doing small batches of heat treat in my shop to improve delivery time on lower quantity orders. The idea was to start off working with steels that don't require cryo treatment to get solid results and then add cryo to my shop. Can't add cryo at this time. With the current situation and the uncertainty of whether heat treat shops will be open and for how long, I need to look at heat treating without cryo. I am curious what can I expect the results to be.

Here are the steels are ready for heat treat,

AEB-L, Nitro-V, M390, Vanax, Z-FiNiT, N690

Brad from Peter's already helped with Nitro-V.

Thanks in advance.
 
Get a small top opening floor standing household freezer with turbo freeze mode. It will get you to -45 Fahrenheit. Very good compromise!
 
AEB-L needs -95F which is dry ice, LN doesn't really buy you more, other than perhaps ETA carbides. A -5F in home freezer is better than nothing. If I were HT'ing enough to make dry ice too expensive, I'd bite the bullet and get a dewar for LN.
 
I heat-treat high-temp blades with sub-zero. it's infrequent enough that I do a run in my friend's kiln about once a month. 10lb of dry ice costs $15 from a local supplier, which amortized across 3 blades is a very modest cost increase per unit, and the stuff keeps in a cooler for a couple days at least. Yo you could heat-treat all weekend for that $15 and the inconvenience of picking it up. (I have to drive 30min to a specialty ice supplier)

Sub-zero appears to be the most bang-per-degree for RA conversion for someone not ready to deal with LN dewars and suppliers.
Both Crucible and Sandvik specify sub-zero for 154C/P/M and 13C26 (AEB-L). Not sayin' you can't do incrementally better as per Larrin's testing, but you can hit nominal quench targets fairly easily w/ dry ice.
 
I use sub-zero. I put about 3# to 5# dry ice (about $2/lb from Harris Teeter grocery store) in a long narrow pan (whole fish pan) and pour about 1/2 gallon of denatured alcohol over it (stove fuel alcohol form the hardware store - $15 a gallon). The alcohol is reusable again and again for years. It will do a batch of twenty blades easily ... or one blade if that is all I have to HT. Works fine for CPM-154, S35VN, S30V, AEBL, 440-C, D-2, and most all other standard stainless steels.

Caution:
The sub-zero bath looks pretty harmless in the pan after a while .. just a bubbly clear liquid ... but it is really cold. It will freeze your fingers if you try and fish a blade out quickly. Use tongs or needle nose pliers to take out the blades. The blades are also very cold and will freeze burn your fingers. Use gloves or let them warm up a minute or so before picking them up with bare hands.
 
daizee said:
I heat-treat high-temp blades with sub-zero. it's infrequent enough that I do a run in my friend's kiln about once a month. 10lb of dry ice costs $15 from a local supplier, which amortized across 3 blades is a very modest cost increase per unit, and the stuff keeps in a cooler for a couple days at least. Yo you could heat-treat all weekend for that $15 and the inconvenience of picking it up. (I have to drive 30min to a specialty ice supplier)

Sub-zero appears to be the most bang-per-degree for RA conversion for someone not ready to deal with LN dewars and suppliers.
Both Crucible and Sandvik specify sub-zero for 154C/P/M and 13C26 (AEB-L). Not sayin' you can't do incrementally better as per Larrin's testing, but you can hit nominal quench targets fairly easily w/ dry ice.
Click to expand...

some steels like z-wear or V4e show performance improvements with full cryo. S35vn gets an additional Rc point with cryo over sub-zero, but adjusting tempers erases any advantage. Most steels are fine with sub-zero.

I got my dewar as I live in the country, and my 20l dewar lasts 5 months. It’s just more convenient to have it on hand when needed. I fill it twice a year.
 
For what its worth you can get into cryo for about $250. I think its worth it. My small dewar keeps liqid nitrogen for about 2 and half months.
 
2.5mo is impressive! 5mo! Hmmm.

Tho at this point I've decided I don't need to chase exotics, and if my steels are happy with sub-zero only, that's good for me.

Dang, Stacy, wish I could get dry ice that easily. You'd think being near the coast with all the fishing in Rhody that it would be available... nope. I keep asking other people...
 
daizee said:
2.5mo is impressive! 5mo! Hmmm.

Tho at this point I've decided I don't need to chase exotics, and if my steels are happy with sub-zero only, that's good for me.

Dang, Stacy, wish I could get dry ice that easily. You'd think being near the coast with all the fishing in Rhody that it would be available... nope. I keep asking other people...
Click to expand...
My local publix has dry ice. And, if you order meat from Omaha Steaks, they send it packed in dry ice. Win-win.
 
daizee,
Check around more. Dry ice is far more common than most people think. Many places have it that yu wouldn't think do. Ask doctors and veternarians where they get theirs as well as check with the local welding shops and ask them who has it ( Air-Gass usually has it). Call every big grocery in town and check. Call some seafood suppliers that sell by mail
A quick search says that there are plenty of places near you.
https://www.bing.com/search?q=rhode...b4392453ab7a37fb1e710c814&FORM=ANAB01&PC=U531
 
Dry ice supply is a bummer in Canada. You can only get it from a welding supply store and its considered hazardous. Silly as you breath the stuff out.

That's why I got a Dewar. It was a pain trying to get to praxair during the week. With a Dewar you're good for a couple months
 
Yeah, I've called around a lot. Nobody actualy has it. The internet lies. (we're all shocked, I know)
The welding supply shops sometimes do, but they are all at least as far away from me.
Vets are a good idea, there are a couple nearby. If I thought I could get a dry-iced steak reliably delivered with short notice on a Saturday, I'd totally do that! :D

My girlfriend is a plant physiologist with a -80 freezer, but she only gets samples or low-temp chemicals shipped occasionally. Used her leftover ice once. :)
 
The only sources of dry ice near me are just as far as getting liquid nitrogen so the LN2 is definitely more convenient.
 
Steel you mentioned are all requires sub-zero treatment to get to optimum potential.

If you really want to work without freeze treatment then you better use steel like low alloy or high speed with high temp tempering instead.
 
I freeze using -45 F myself (household freezer, turbo freeze mode). When doing RWL-34 at 1950 F and 2 hr 350 F temper, this gives me 63 Hrc. Plenty hard.
I wonder if the difference going to dry ice really could be experienced in use? It would give me what, 2-4 % less RA?
What do you guys think?
 
I think people worry too much about RA. The amount is small in most cases as long as you get down low enough. In your case, -45°F seems low enough for the steel you are using. With a temper selected to adjust the hardness up a bit, the end result is acceptable.

Larrin,
If using a low temperature quench like a -45° freezer, would there be any benefit to a cold treatment between tempers or a third temper (to lower RA).
 
Thanks everyone for the input. It has really helped. I appreciate it.

Stay safe
 
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