3V and cryo revisited...

G

gixxer

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I have done a search in the forum for info on the differences between HT'ing using cryo and a low temper, and no cryo and 1000deg temper. Pretty much it seems that either way you get rid of the retained austentite, so why would one person use cryo and another not? Is the only reason one simply does not want to temper at 1000, or is there more? Is one HT more suited to smaller blades that are not choppers? Just throwing ideas out there. I am considering using 3V cause it does not "require" cryo and that just makes life simpler.

Random question, why is it that not many folks use 3V? This is of course from my limited observations in the BF gallery and for sale area of course...:D
 
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I'm sure he'll chim ein, but what I've learned from Butch Harner about 3v are the following things:

- Wow, makes a great "hard use" knife.
- Higher temper at 1000F is generally targeted at industry that cares about dimensional stability in parts
- Cryo + lower tempering works just fine.
- 1000F temper should also work just fine (though I expect Butch will chim in with his experience here).

-d
 
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Change that last line to 1000 F !
Jerry Hossom is a 1000 F temper guy and he certainly has done lots of work with 3V.Maybe he'll respond.
I'm in the 400 F group.
Either will work .There are often choices that can be made in HT of steels .Things like a little change in corrosion resistance , or toughness .One of my reasons for picking 400 F is the problem of one oven and waiting for it to cool. With 400 F you can use a toaster oven etc to temper.BTW there's no reason you can't temper at 400 F for any steel for safety , then at some further time continue at 1000 F for example.
 
deker said:
I'm sure he'll chim ein, but what I've learned from Butch Harner about 3v are the following things:

- Wow, makes a great "hard use" knife.
- Higher temper at 1000F is generally targeted at industry that cares about dimensional stability in parts
- Cryo + lower tempering works just fine.
- 100F temper should also work just fine (though I expect Butch will chim in with his experience here).

-d
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im sure your last line ment 1000f

and deker sums it up well in my use thats how it reads
at 1K f temper you are on the 2ndary hardness curve mych like cpm154 and other high alloy steels that were never really ment to be knife steeland as such have Hts that are for there intended use (154cm was more for jet engine parts i think )

also one of the things you have to look out for at the high temps is the fact that the temp window is really tight and 25f difference can make up to 3 points of hardness change. so if you over shoot things can go south quickly

i have only tested my blades after 1000f and 400f for hardness but one of these days i will try and do 425 -550 in 25f steps to see what kind of curve ther is

im not much for typing or spelling so if anyone can read butchese and cares to part translate they are welcome to it :)
 
Using the upper temper means a precipitation of carbides that can lead to reduced toughness. Roman Landes says that in his testing the edge stability is reduced when using an upper temper versus the lower one.
 
Larrin said:
Using the upper temper means a precipitation of carbides that can lead to reduced toughness. Roman Landes says that in his testing the edge stability is reduced when using an upper temper versus the lower one.
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so could we safely say that if I were making a chopper or hard use knife that I would use the cryo and low temper, but if it were a light use knife edge stability would not be that big of a deal?
 
Edge stability is what allows "light duty" knives to support fine thin edges that cut like crazy. I think light duty knives need the lower temper even more.

The additional hardness at high temps is the result of additional carbides. So you end up with a carbon lean (weak) martensite with lots of carbide in it that reduces the depth a diamond penetrator will reach in the hardness test. The two scenarios, while have similar HRC values, are not the same.

For something taken to a knife edge, I suggest you try the low temper. And use cryo to address the RA, because otherwise you will leave a lot "on the table" at the lower temper temps due to RA.

3V looks to me to be similar to HSS, which is commonly plagued with over 20% RA. If you can stomach it, I'd go directly into cryo as a part of the quench.

my .02...


Lets see what mete has to say...
 
appears that my interpretation of edge stability is misconstrued. My perception was that of an edge holding up to hard use and cutting hard materials. but I do understand your explanation. What good is it to have a fine grain for a fine edge if the steel cannot handle a fine edge cause of the outcome of the HT. If it did come down to it cryo is doable for me. That being the case I guess I would stick to the CPM154 I have laying around. I am getting spun up to HT like this weekend for the first time.
 
I'm curious. Assuming the impossible; identical blades, geometry, hardness, etc... how big of a difference would one think there to be in terms of toughness, edge stability, and overall performance? Like say if it were a chopper? Any guesses?
 
i run all my cryo steels right from quench to room temps and into LN2 for at least 2 hours or over night (depends on the kiln cooling to 400F and my time line)
as stated before that high temp is more for dimensional stability in die making use in 3v

i will also say that if you are not cryoing cpm154 you are also leaving much on the table
 
Gotta ask. I'm looking at Crucible's data sheet on 3V and it doesn't say anything about a 400 degree temper. Where are you getting your data?

Triple temper at 400 would sure leave a cleaner blade than triple temper at 1000.

Rob!
 
That Crucible datasheet is incomplete, but I think they want you to harden 3V a certain way for industrial parts.

In any case, I've tried both the 400F temper and 1000F temper. In short, the 1000F temper 3V pits readily while the 400F temper 3V is basically like stainless steel in corrosion resistance. They are otherwise both good performers.

For max hardness temper at 950-966F, depending on austenization temperature. Most ovens don't have accurate temperature readings though.
 
if you need more thenn 61-62rcin 3v you better find a different steel (i have heard of 63 but not fror most use)
afterall the data sheet shows just .80 carbon so its a fight to make sure you get full hardness after the steel starts making carbides let alone after tempering
 
butcher_block said:
i will also say that if you are not cryoing cpm154 you are also leaving much on the table
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I do intend to cryo my cpm154.



After hearing what some folks have to say I can pretty much figure out that right now I do not need to buy any 3V. Maybe down he road after I run out of what steel I have now.

I also want to plate quench come super thin O1 but that's another thread. Visions of slippies dance in my head...
 
butcher_block said:
if you need more thenn 61-62rcin 3v you better find a different steel (i have heard of 63 but not fror most use)
afterall the data sheet shows just .80 carbon so its a fight to make sure you get full hardness after the steel starts making carbides let alone after tempering
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I would figure something like M4 would overtake it in properties once you try to push it too high. It would seem to be a better idea to stop jumping through hoops at a certain point to get a steel harder or tougher through heat treating and to just use a different alloy with a less delicate process and more repeatable results.
 
hardheart said:
I would figure something like M4 would overtake it in properties once you try to push it too high. It would seem to be a better idea to stop jumping through hoops at a certain point to get a steel harder or tougher through heat treating and to just use a different alloy with a less delicate process and more repeatable results.
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:thumbup::thumbup:
thats riight i dont care who you are and what your pet steel is
pick the steel that is best or close to the best for you app. too many times have i heard that "my steel is good for jsut abuot everythign i just change the HT a bit "

ppl wander why im not a nfan of cpms30v and its cause while it does everythigk ok (hell of a folder and small hunter steel) i find that it gives up performance in other knives (i dont make too many folders )
 
butcher_block said:
too many times have i heard that "my steel is good for jsut abuot everythign i just change the HT a bit "
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I have not been around the block as long as most of you guys, but I definitely agree with your outlook on that statement. That is like trying to get an F350 to run the circuit at Misano like a Ferrari Enzo by changing the tires and using race gas.
 
Data sheets are on the new website . www.crucible.com
They may not be 'complete' but remember those instructions are for typical use which may not include knives !
 
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