3V Heat Treatment

[i4Marc]

Well, in addition to the mouth opening, the usable internal length is also a concern. With a 10L dewar giving you something like 10" of usable height/length it doesn't give you a lot of options as far as the kinds of blades you can treat. I don't have the cash for a 50L wide mouth but I'm trying to get an idea of what kind of vessel I'd need for when I hit the lottery (it's coming, I can feel it ). The cooler seems like a more reasonable temporary solution. I guess I'd still need a dewar to transport the nitrogen.

 

[kuraki]

You need the dewar to transport but also to hold. The cooler won't hold for more than a day. They're just not well insulated enough.

I don't know where you're getting the 10" from though. It's -275 degrees whether you're in the liquid or not. So you can cheat with the 10L bottles and after you put your 15" blade in, just let the styrofoam plug sit where ever it sits. Length has only stopped me on the very longest knives I make, 15" blade plus 5" tang bowies. In reality if it fits in the length of the kiln I'm using, it fits the length of my dewar.

 

[jdm61]

A couple of years ago, used veterinary dewars, even the big ones like the wide mouth 25 and 30 liter ones, could he had for reasonable money. They might not have been in the best shape, but they were out there. Like a lot of stuff that we find useful, the prices have gone up and the availability down over the last few years, at least on E-Bay. Wishing that I had bought all of the large used dewars, 18 inch surface grinders, beat up Rigid pipe threaders and old anvils that I could lay my hands own like 5 years ago.

 

[i4Marc]

kuraki,

I only did some quick visual math using a photo of a 10L dewar and estimating for the length of the plug and thickness of the walls etc. If you are using a 10L and can get a 15" blade plus a 5" tang in there that would work for 90% of what I do.....but the mouth opening would still be a problem at times.

Anyway, to get back on the rails, thanks everybody for sharing your advice on the 3V.

 

[kuraki]

Oops, no, that's an example I can't fit. I can get about 15" total length in mine and the plug is sticking out a few inches. One like JG Custom Metal Works posted would be ideal, it's a little narrower and therefore taller than mine.

 

[HSC ///]

I have a chance to get one of these -

https://www.labrepco.com/store/cate...category-title/Aluminum_Dewars_liquid_storage

Features Include:

• Designed for large capacity storage
• Low liquid nitrogen consumption
• Convenient lightweight package
• Durable, tamper-proof lid design
• High strength neck tub reduces liquid nitrogen loss
• Strong light weight aluminum construction
• Advanced chemical vacuum retention system
• Spider design on platform for easy retrieval and insertion of product canisters

Specifications:

• Performance
  • LN2 Capacity L: 10
  • Static Evaporation Rate* L/day: 0.18

• Unit: Dimensions
  • Neck Opening in. (mm): 2.18 (56)
  • Usable Height in. (mm): 13.5 (343)
  • Overall Height in. (mm): 21.5 (546)
  • Outer Diameter in. (mm): 10.3 (260)
  • Internal Diameter in. (mm): 8.3 (210)
  • Weight Empty lb. (kg): 12 (5.4)
  • Weight Full lb. (kg): 31 (14)

is this suitable for cryo HT of knives?

 

[JTknives]

Suitable, Yes. Recommended, NO.
For the size of the opening it has crap for evaporation rate. But if your getting LN for super cheep then it does not matter. I think evaporation rate matters a lot more to the hobbyists then it does to guys that do a lot more blades. If you do a crap ton of knives then your going to burn through your LN rather fast anyway. But guys that do one or two Knives a month really need to conserve gas. If there numbers are correct then you get 55 days between fillings. After you do a blade(s) and given the cheaper dewar manufactures might fudge the numbers a tad you get say 30days. That means if you do one knife a month it’s going to cost you an entire dewar of LN for one or two blades. I don’t know that brand personally but I would recommend staying away from white. I had one of there dewars and the evaporation rate sucked. I sold it and did a ton of research befor I bought a second. And from my reseearch the VWR brand is at the top. Here is a screen shot of there website and I circled the one I bought. Trust me buy once cry once, buy cheap replace next week.

 

[One Armed]

I think that dewar is perfect. I would actually be buying even cheaper than that. I simply could not imagine spending over $2K on a dewar!?! I would be crying FOREVER if I did that! I guess it’s the same school of thought as spending $4K on a belt grinder and thinking it’s somehow making your blades superior.....

LN2 is CHEAP! Like crazy cheap! I was quoted like $25 or $30 to fill a 10L dewar. So if you need to fill it once a month, I’m not sure why $30 a month is expensive??? Especially if you only spent $500(or even LESS) on the dewar! But some have the need to purchase ultra expensive tooling, and justify by recommending others should, or what they have is garbage! Oh well.

 

[HSC ///]

Suitable, Yes. Recommended, NO.
For the size of the opening it has crap for evaporation rate. But if your getting LN for super cheep then it does not matter. I think evaporation rate matters a lot more to the hobbyists then it does to guys that do a lot more blades. If you do a crap ton of knives then your going to burn through your LN rather fast anyway. But guys that do one or two Knives a month really need to conserve gas. If there numbers are correct then you get 55 days between fillings. After you do a blade(s) and given the cheaper dewar manufactures might fudge the numbers a tad you get say 30days. That means if you do one knife a month it’s going to cost you an entire dewar of LN for one or two blades. I don’t know that brand personally but I would recommend staying away from white. I had one of there dewars and the evaporation rate sucked. I sold it and did a ton of research befor I bought a second. And from my reseearch the VWR brand is at the top. Here is a screen shot of there website and I circled the one I bought. Trust me buy once cry once, buy cheap replace next week.

thx for the info
this dewar was used in a medical facility unit, it's owned by a physician who had his own practice, he's asking $125 for it....
I don't expect to use it very often, perhaps even just once or twice a month, mostly to try Damasteel.

"local" praxair which is an hour away, charges $10.31 per liter, so $100 to fill it.

I suspect most of the time the dewar will sit unused, and then I'll batch process whatever at one time, then maybe not used it again for one or two months.

 

[One Armed]

Wow! They want that much to fill?? You don’t have any welding/gas shops around you? Place that sells tanks of Argon and what not?? Several of those around me. Closest one is only about 1.5miles and when I checked on it about a year ago, was only a few bucks per Liter.


Still, even at $100... that would still work for me. But again, I decided NOT to build an oven, and continue having Brad take care of my heat treat.

I just got to thinking about it, and it dawned on me that Brad has been doing this for a long time. And he does it ALL DAY, ALL WEEK! For me, or really anyone, to think they are going to spend a few days...weeks, even months, and achieve results as good as what someone like Brad can delivers is well, just a bit naive.

 

[JTknives]

I think that dewar is perfect. I would actually be buying even cheaper than that. I simply could not imagine spending over $2K on a dewar!?! I would be crying FOREVER if I did that! I guess it’s the same school of thought as spending $4K on a belt grinder and thinking it’s somehow making your blades superior.....

LN2 is CHEAP! Like crazy cheap! I was quoted like $25 or $30 to fill a 10L dewar. So if you need to fill it once a month, I’m not sure why $30 a month is expensive??? Especially if you only spent $500(or even LESS) on the dewar! But some have the need to purchase ultra expensive tooling, and justify by recommending others should, or what they have is garbage! Oh well.

Wait what? Where is this hostility coming from. You need to check your attitude at the door. Poping off half cocked is what drives experanced bladesmiths away from helping here. All I was saying is VWR dewars are amazing. I think I paid like $650 for mine. If you watch eBay you can find them for a reasonable price. And $30 a month adds up quick if your only doing 1-2 knives a month. At that rate you might as well send them out for heat treating. My dewar holds liquid nitrogen around 222 days not including use. At his price of $10.31L and filling up once a month would cost him $1,237.00 a year. Now double the efficiency and he has now magically saved $618 a year. That right there pays for a good dewar. So befor you get all worked up becaus you think we just like pissing money away, maybe you should do some simple math.

 

[HSC ///]

You don’t have any welding/gas shops around you? Place that sells tanks of Argon and what not??

..... is well, just a bit naive.

no I don't, it's a small town, In central/northern AZ, there is plenty of land that is cheap, gas is cheap, but not everything else is cheap, some things are more expensive, groceries cost more, household services can cost more....even the lack of availability of liquid nitrogen can make it cost more.

and thanks for your opinion....

you had an incredible "sense of accomplishment and thankfulness" when you did you grinder build, didn't it occur to you that it's "just a bit naive" to think you can build something and achieve as good results as a grinder manufacturer who does this all the time.....

 

[One Armed]

no I don't, it's a small town, In central/northern AZ, there is plenty of land that is cheap, gas is cheap, but not everything else is cheap, some things are more expensive, groceries cost more, household services can cost more....even the lack of availability of liquid nitrogen can make it cost more.

and thanks for your opinion....

you had an incredible "sense of accomplishment and thankfulness" when you did you grinder build, didn't it occur to you that it's "just a bit naive" to think you can build something and achieve as good results as a grinder manufacturer who does this all the time.....

Huh?? Don’t get it...I’ve been supporting you in this the whole thread!

And YES! It would be naive to think I can BUILD a belt grinder....or SGA as nice as someone like Travis Wuertz!! Which is why I have always claimed that those machines are WAY nicer than my own. But talking about a TOOL and a person’s SKILL are two very profoundly different things. Grinding.....Heat Treatment....???

Like I said I supported your choice TO HT, your choice in dewar and especially going CPM3V. Simply came to the realization that “I” would not be able to match Brad’s technique.

So to answer your question again.... Yes, it’s naive. Later!

On a side not*
To quote, call someone out and reference another thread where the person was thank The Lord for be blessed with certain abilities....despite being 100% disabled and having use of only ONE ARM/HAND.....is just outright disgusting! Bad form! Bad, bad form!

 

[HSC ///]

The thing you don't get, is that there are some people who shout so loud, you can't hear them...

you didn't say "I" - you said - "For me, or really anyone,"

I'm very sorry i4Marc to take up your thread

 

[Nathan the Machinist]

Wow this thread took a real dump huh?

I think almost everybody here knows that the best heat treats for 3V, that a bunch of people who have been working at it for years have figured out, has been the "low temper" approach which avoids the secondary hardening hump. This forum and the makers here are past the point of "just do what it says to do on the data sheet, that is the best possible". The well understood reality is the high temper approach works best for stamping tools and the low temp is a better approach for a knife edge. Two different animals with different needs.

And I think most people here have come to appreciate that there is more to a steel than just it's hardness. That two identical blades with identical geometry and steel type can be heat treated in very different ways and have very different properties but have the same Rockwell Hardness. We all get that now, right?

So, with 3V you have things like material condition, austenitizing times and temps, quench rate, cryo and the timing of steps to play with. And when you do play with it (real controlled functional testing, not just RC testing) you will eventually find that the best 3V is done using a lower tempering temperature, no secondary hardening. And along the way you will also find that the low temp approach is not at all fool proof. You can screw that up. The steel was never designed to be used that way and some "industry best practices" such as tempering before cryo will prevent you from having success with 3V when using the low temper approach. This is all really obvious with experimentation. In fact there is a pretty deep rabbit hole you can go down but you may find there are areas of diminishing returns on a heat treat and honestly for most applications there is nothing wrong with accepting "very good" if "perfect" is out of reach. Especially on the subject of 3V, whose industry standard heat treat as specified by Crucible leaves a great deal "on the table" when applied to a knife and most of the HT shops aren't doing it right. Most of the people on this forum can do 3V better than most HT shops (Peter's HT being a notable exception).

Have a good oven with good temperature control, this is not a good application for a pottery kiln or forge
control your times
you need a relatively rapid quench
Get as close of Mf as possible as a part of your quench
take it easy on the tempering temps, don't exceed 500F

^ the basics are really simple

Things like eta carbide formation optimization and the effects of martensite formed during tempers rather than in the primary quench and minimization of RA and the pursuit of some holy grail of optimized and even microstructures can eek out that last little bit of whatever you're after but you will find, with experimentation, that is it possible to achieve pretty good results without going overboard with the technology AS LONG AS YOU TEST YOUR PROCESS AND VARIATIONS OF IT IN CONTROLLED TESTING AND AGAINST KNOWN STANDARDS.

You'll never do a good job with 3V with something like a torch, but there is more than one way to skin this cat and if dry ice is all you have, you can make it work. There is more you can do with LN, but just because you have it doesn't mean you're using it right so at the end of the day it may not make that much difference for a particular person. And as long as you test, validate and repeat your process it doesn't matter.

You can get a very good 3V HT at Peter's. It was good years ago and it is even better today. You can also do every bit as good at your own shop with decent tools if you do your homework. We're not talking about thousands of hours of homework either. Spend a week on it and your work will be better than most, even if you only have dry ice. Look at the material condition going into HT, aust times and temps, quench rate and the application of cryo. <-- that will get you there.

There are no short cuts, it's 3V not 1084. If you're not willing or able to use appropriate tools and techniques, send it out. But something better than 90% of the industry is well within your grasp.

 

[samuraistuart]

Excellent reply Nathan. Thanks for your time and input. Always a cool, educational post.

 

[One Armed]

Thank you Nathan. Pleasure to read.

And to everyone, forgive me for responding and adding to items which caused the “Taking a Dump”, as Nathan pointed out. This really is a good thread.

 

[koduu]

So, with 3V you have things like material condition, austenitizing times and temps, quench rate, cryo and the timing of steps to play with. And when you do play with it (real controlled functional testing, not just RC testing) you will eventually find that the best 3V is done using a lower tempering temperature, no secondary hardening.

Could someone please tell me why is that so? I am hoping to make some skinning knife test blades out of vanadis steels (vanadis 4E and 10) that would hopefully have as shallow as possible edge angles and highly agressive and long lasting cutting agression. Using LN all the time would get cuite bothersome and pricey in the long run so what are the drawbacks of going for high tempering instead of cryo+low tempering?

Uddenholm states in its knife steel document that cryo + low termpering should be used for its stainless PM steels for corrosion resistance, but for vanadis series they say that high tempering is the way to go.

FOR VANAX and ELMAX - "Low-temperature tempering
is recommended to ensure good corrosion resistance, but
if necessary, clamp tempering can be used in the range
450–500°C (840–930°F)"

FOR VANADIS and SLEIPNER - "The Uddeholm Vanadis and Uddeholm Sleipner series
are heat treated according to normal procedures. As they
are non-stainless, high-temperature tempering is recom
mended. Therefore deep cooling is no longer necessary
to attain full hardness."

quoted from https://www.uddeholm.com/app/upload...holm_Premium_Steel_for_Knives_Eng_1703_e6.pdf

 

[hugofeynman]

Could someone please tell me why is that so? I am hoping to make some skinning knife test blades out of vanadis steels (vanadis 4E and 10) that would hopefully have as shallow as possible edge angles and highly agressive and long lasting cutting agression. Using LN all the time would get cuite bothersome and pricey in the long run so what are the drawbacks of going for high tempering instead of cryo+low tempering?

Uddenholm states in its knife steel document that cryo + low termpering should be used for its stainless PM steels for corrosion resistance, but for vanadis series they say that high tempering is the way to go.

FOR VANAX and ELMAX - "Low-temperature tempering
is recommended to ensure good corrosion resistance, but
if necessary, clamp tempering can be used in the range
450–500°C (840–930°F)"

FOR VANADIS and SLEIPNER - "The Uddeholm Vanadis and Uddeholm Sleipner series
are heat treated according to normal procedures. As they
are non-stainless, high-temperature tempering is recom
mended. Therefore deep cooling is no longer necessary
to attain full hardness."

quoted from https://www.uddeholm.com/app/upload...holm_Premium_Steel_for_Knives_Eng_1703_e6.pdf

Send an email to Fredrik Haakonsen or become Roman Landes friend on Facebook and ask them why! Don’t know anyone smarter than those gentleman in the knife world. Maybe Cliff and Jerry can answer to, but Cliff takes forever to answer.

 

[Nathan the Machinist]

Could someone please tell me why is that so? I am hoping to make some skinning knife test blades out of vanadis steels (vanadis 4E and 10) that would hopefully have as shallow as possible edge angles and highly agressive and long lasting cutting agression. Using LN all the time would get cuite bothersome and pricey in the long run so what are the drawbacks of going for high tempering instead of cryo+low tempering?

Uddenholm states in its knife steel document that cryo + low termpering should be used for its stainless PM steels for corrosion resistance, but for vanadis series they say that high tempering is the way to go.

FOR VANAX and ELMAX - "Low-temperature tempering
is recommended to ensure good corrosion resistance, but
if necessary, clamp tempering can be used in the range
450–500°C (840–930°F)"

FOR VANADIS and SLEIPNER - "The Uddeholm Vanadis and Uddeholm Sleipner series
are heat treated according to normal procedures. As they
are non-stainless, high-temperature tempering is recom
mended. Therefore deep cooling is no longer necessary
to attain full hardness."

quoted from https://www.uddeholm.com/app/upload...holm_Premium_Steel_for_Knives_Eng_1703_e6.pdf

Rockwell hardness is only measuring the depth of the dent from a diamond penetrator. It doesn't tell you the whole story. The secondary hardening hump is precipitating additional secondary carbide at the expense of creating carbon lean martensite (soft and weak). In thick sections like a stamping tool this is okay, but it falls apart in a thin knife edge. If you'll try V4E with high temper and with a properly executed low temp process the difference is very obvious in side by side testing. The secondary hardening hump makes V4E chippy with poor edge stability at narrow angles. The edge fails in use. A properly done low temp process has fantastic edge stability in V4E, the end effect being dramatically improved edge retention in rough and regular use. The only application where the high temp has good edge retention is in light controlled cuts such as sawing at abrasive paper card stock or slicing rope. But normal real world use does much better with the low temp process.