Cru Forge V Toughness Testing

Larrin, it looks like the second graph is using the "old reliable"1500/400F recipe MOL. Is that correct?
 
The point of this steel was lost when Crucible failed to properly release it. They had bigger issues to contend with, one could say... Dan Farr was the driving force behind this steel. It was his desire to create a steel that would offer improvements in wear resistance that could also be readily forged. To my knowledge, it was the first forging steel designed from the ground up for cutlery applications. Many bladesmiths were and are still working with minimal equipment and 'uncontrolled' heat sources. The premise of the 'get it hot and dunk it' idea was that this steel would offer dramatic improvements over what most guys were using, without the demand of rigid temperature controls or special quenchants. In fact, Dan demonstrated HOW this was done in most forges in front of the PhD metallurgists that were developing the alloy with him by bringing his equipment to their facility in Syracuse and making a few blades from start to finish.

Can you improve on the performance through better control and process? Sure. The difference, though, is that this alloy offered dramatic improvements to what was previously available and still allowed the 'by eye' guys a better option.

I know where you're coming from, Warren, but I wanted to add this for the record. It was very important to Dan.

Willie71 said:
I always thought get it hot and dunk was just not good enough,
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I believe there are several Japanese steels designed for bladesmiths that are older.
 
I doubt that cruforge v is any more sensitive to temperature than other forging alloys. 1095 has a relatively small volume of easily dissolved cementite that with over-austenitization would also have brittle plate martensite. All bladesmiths would benefit from good temperature control.
 
Yes Larrin ! While I knew what Dan was attempting, My old tests of ability to reproduce temps by eye were not nearly as some would tell you ! So first proper control would be more reproducible ,more precise choice of temperature could be chosen. All my tests were always checked with modern temperature measurement .
Mention of Cryo brings up another problem as cryo seems to be one of the latest fad words without most using proper terms and being able to define what is . Just reduction in RA or also formation of eta carbides ?
For all those who want to make their own notched impact specimens - dimensions are critical especially smaller samples .
Playing with steels for maximum performance is not done casually even though Dan and others would like to. Nothing here personally against Dan .
Our modern micro-alloying includes "micro-HT "
 
Matthew Gregory said:
The point of this steel was lost when Crucible failed to properly release it. They had bigger issues to contend with, one could say... Dan Farr was the driving force behind this steel. It was his desire to create a steel that would offer improvements in wear resistance that could also be readily forged. To my knowledge, it was the first forging steel designed from the ground up for cutlery applications. Many bladesmiths were and are still working with minimal equipment and 'uncontrolled' heat sources. The premise of the 'get it hot and dunk it' idea was that this steel would offer dramatic improvements over what most guys were using, without the demand of rigid temperature controls or special quenchants. In fact, Dan demonstrated HOW this was done in most forges in front of the PhD metallurgists that were developing the alloy with him by bringing his equipment to their facility in Syracuse and making a few blades from start to finish.

Can you improve on the performance through better control and process? Sure. The difference, though, is that this alloy offered dramatic improvements to what was previously available and still allowed the 'by eye' guys a better option.

I know where you're coming from, Warren, but I wanted to add this for the record. It was very important to Dan.
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I get this, and understand the reasoning. Using about 0.8 to 0.85% carbon would help minimize the potential problems with hypereuctoid steels. Having extra to deal with decarb makes some sense too though.
 
I appreciate the science and effort behind this endeavor, and I also understand the notion that the most can be gained from any steel by precision and repeatability. The reality for someone like me who is a hobby bladesmith is that my fun money for this went to a forge and an anvil, not a heat treat oven that can provide exact temps for given soak times. It seems to me the folks who prefer the stock removal method and have spent their money on an oven instead of a forge and anvil have quite a few options of alloys to work with. The appeal to me with cruforge v was exactly what Mathew was talking about. Get a little more performance without needing to get into the higher precision requirements (and not having something that is ruined by the variance of heats during forging). I've made one knife from the stuff and have steel to make one more. That may be my last from it though because it concerns me that it's never going to be made again, so I feel like I need to find something to get attached to as my go to that I know will be around. It's also less than fun to hand finish ;)
 
There is no need to be defensive about your knifemaking methods. We will be doing similar analysis on other steels and the choice of CruForgeV does not make any political statement. The toughness data is provided for you to do with what you wish. The data will not criticize your knifemaking prowess or your mother's weight. The data will not offer any opinions about the joy of smelling propane or of steel dust. :)
 
As a end use consumer of knives, I find this thread fascinating. Do I understand all the details of making, heat treating, and finishing knives, no. But this thread along with others from Carothers on 3V, D2, and 4V, Hellcat bearing knives from Daado, videos and step by steps from other makers of knives and sheaths help round out my understanding of some of the processes that go into the craft I'm ultimately paying into as a consumer. And charts and graphs of knife stuff is just freaking cool.

Helping my favorite makers use CRU-V to dial in better performance for future knives I buy from them is an excellent byproduct in my book.

Thanks for the thread and analysis.
 
Haha. Very well Larrin. Well, if you have extra steel and time, it might be interesting also to see how an old school unscientific heat treat lands in comparison to your final optimal results. It'd be neat to know where us propane sniffers are landing with this steel.
 
On to the next controversial topic: triple quenching. There are several old papers showing an improvement of properties through multiple austenitize and quench cycles which are performed to refine the grain structure and improve toughness. We did a triple quench by austenitizing and quenching twice from 1450°F, followed by the final at 1500°F. There was a small increase in hardness and a decrease in toughness. Could other methods of multiple quenching improve toughness? Possibly. Without metallography we won't know if the grain was actually refined. However, the grain size being smaller is not a guarantee of toughness improvement. Furthermore, it is sometimes assumed that any type of "reasonable" triple quenching process will lead to an improvement in toughness. This data appears to show otherwise.

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jdm61 said:
Larrin, it looks like the second graph is using the "old reliable"1500/400F recipe MOL. Is that correct?
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The second graph uses an austenitizing temperature of 1500°F.
 
That is interesting not only because that is the "default" recipe for some of us, but also in that you seem be getting hardness levels slightly higher than what the "factory numbers" tell you to expect. That might explain some of the difficulty in hand sanding above and beyond the mere fact that the steel has a fair bit of vanadium. ;)
 
jdm61 said:
That is interesting not only because that is the "default" recipe for some of us, but also in that you seem be getting hardness levels slightly higher than what the "factory numbers" tell you to expect. That might explain some of the difficulty in hand sanding above and beyond the mere fact that the steel has a fair bit of vanadium. ;)
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I don't believe the numbers reported in the data sheet included a cryo treatment. That would be the easiest way to explain higher hardness here.
 
Hmmmm. Do you think you would get any additional benefit from also using say the high temp salt and medium-fast oil hardening process like some are doing with 52100? Also, do you think that a "cold" treatment using the dry ice slurry method would be sufficient for this steel?
 
jdm61 said:
Hmmmm. Do you think you would get any additional benefit from also using say the high temp salt and medium-fast oil hardening process like some are doing with 52100? Also, do you think that a "cold" treatment using the dry ice slurry method would be sufficient for this steel?
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I can't say what the effect of different quenchants would be at this point. For reducing retained austenite you want to get as cold as you can, dry ice is better than room temperature. You will likely eliminate most of the retained austenite with dry ice.
 
I just picked up a bar or two of this from AKS, and am excited to try it. Do you think Parks 50 is an acceptable quench?
 
What Hoss said. I have used #50 for thicker blades, but I had a thin, partially beveled kitchen knife blade absolutely explode after the quench. I immediately ordered some McMaster-Carr AAA equivalent.
 
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