How much does "toughness" matter?

Rooster81 said:
A great example of an empirical test! I'd be curious about the following:

Material and hardness of knife
Material and hardness of chain
Method of cutting (battoning or similar or slow continuous pressure applied)

Fascinating stuff!
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I forgot exactly which CPK model Nathan used for that chain link cut. It looks to me like one of the Basic Field Knives, BFK. He uses a weird looking hammer to hit the blade with. I forgot what it's called because I've never owned a hammer like that. I'll have to go back and find the posts about it to find any of the particulars.
 
000Robert said:
Now I'm starting to question if you are really a knifemaker. Anybody that spends the money can have that under their name.
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Ad hominem is a sign of weakness and incapability. It's good to avoid it. Ergo, still boting.
 
JoeBusic said:
Ad hominem is a sign of weakness and incapability. It's good to avoid it. Ergo, still boting.
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At least I didn't accuse you of botting. So far you have not demonstrated to me that you know the difference between strength, and toughness.
Just because you claim to be a knifemaker doesn't necessarily mean that you are a knifemaker.
 
000Robert said:
At least I didn't accuse you of botting. So far you have not demonstrated to me that you know the difference between strength, and toughness.
Just because you claim to be a knifemaker doesn't necessarily mean that you are a knifemaker.
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I wrote enough here. Can't learn new tricks...
 
Toughness difference between high vs low temp temper and the difference in carbides. 3V toughness dives over 60HRC. At 62 it's close to D2. Sweet spot is 58HRC with high temp temper. Low temp strengthens the matrix and compression strength rises so smashing tests look very good. There is a difference between toughness and impact toughness. Probability that general toughness is better with Delta is high because of the matrix, but stronger the matrix leads to easier cracking at crack propagation sites, which are primary carbides that Delta is seemingly in favor of. So impact toughness is probably lower. One way to find out. :)
JoeBusic said:
Toughness difference between high vs low temp temper and the difference in carbides. 3V toughness dives over 60HRC. At 62 it's close to D2. Sweet spot is 58HRC with high temp temper. Low temp strengthens the matrix and compression strength rises so smashing tests look very good. There is a difference between toughness and impact toughness. Probability that general toughness is better with Delta is high because of the matrix, but stronger the matrix leads to easier cracking at crack propagation sites, which are primary carbides that Delta is seemingly in favor of. So impact toughness is probably lower. One way to find out. :)
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I wonder why Larrin haven’t received some delta 3v coupons to test… nor Infi, btw. If they make the toughest knives, theres a scientific way to prove it. I’m not trying to hurt anyone feelings, I just like science (and toughness) a lot.
 
DangerZone98 said:
Never thought of it that way. I always thought toughness was essential in big blades for withstanding punishment, and not as important for small blades since we don’t really subject our folders and Kepharts to much abuse, i.e. hacking and batoning.

What about hardness though? Does high hardness allow for a thin edge with little risk of chipping as well?
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Forgive me if someone's already answered this, but "hardness" is actually a pretty complicated and fuzzy term. This Knife Steel Nerds article gets into some of the details. Extremely roughly speaking, you could say hardness is the ability to resist plastic deformation. Obsidian, for example, is extremely hard. No matter how much you hammer on a chunk of obsidian you're not going to squish it into a different shape. However, it is also brittle, meaning it's fairly easy to chip/shatter it, which is different from deforming it.

So you want a hard edge so it doesn't "squish," but you also want a tough edge so it doesn't shatter/chip like obsidian.
 
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Rooster81 said:
Agreed, which is why I like to look at BOTH lab test data AND real world use. I think data accumulated from consistent, controlled tests is a great reference and starting point.

But there are so many other variables in play that you also have to look at user experience. In other words, empirical and theoretical are both important. It's also why I appreciate knife makers like Spyderco, they give us so many knives and steels to play with! And Dr. Larrin for his tests!
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Oh yeah, the Spyderco Mule project is a great service to people testing knife steels!
 
patrickguignot said:
I sent an INFI knife to Larrin. Not suitable for a toughness coupon but enough for an analysis. He found the same composition than the A8mod steel so we can use the toughness results of A8mod as a proxy for INFI.
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Yes, I remember. Thank you, in the name of science.
 
hugofeynman said:
Yes, I remember. Thank you, in the name of science.
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Science would require more samples, or the knife maker to agree with Larrin, which didn’t happen.

A8mod has large chemical tolerances, Infi has evolved over time, Larrin has argued with Jerry about this since 2006, and several related threads have been closed since then ....

So we don’t know. What we do know is that Infi and CPM 3V (Delta protocol) have very similar toughness as exhibited in several tests that you can find on BF if you search.
 
hugofeynman said:
Yes, I remember. Thank you, in the name of science.
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This is the kind of "science" that I love! D3V steel knife cut a steel chain link with very minimal damage to the edge. I can't believe that I have to show this photo again so, I'll make it a thumbnail this time.

CPK-Chain-2.jpg
 
000Robert said:
This is the kind of "science" that I love! D3V steel knife cut a steel chain link with very minimal damage to the edge. I can't believe that I have to show this photo again so, I'll make it a thumbnail this time.

View attachment 1962942
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That same (or VERY similar) thing has been done with 1084, 52100, 1075, 80crv2 and probably others by various makers so I'm not sure that example is the definitive "be all, end all" that proves whatever point you're trying to make.
 
J. Doyle said:
That same (or VERY similar) thing has been done with 1084, 52100, 1075, 80crv2 and probably others by various makers so I'm not sure that example is the definitive "be all, end all" that proves whatever point you're trying to make.
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Really? I've been a member here for a little over 2 years and I haven't seen the videos and pictures. Nathan has videos of cutting up concrete pads and stuff. Where are these videos and pictures that you are talking about?
 
000Robert said:
Really? I've been a member here for a little over 2 years and I haven't seen the videos and pictures. Nathan has videos of cutting up concrete pads and stuff. Where are these videos and pictures that you are talking about?
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You know the knife community and knife world are a lot bigger than just bladeforums.com, right? This place, as great as it is, isn't the be all, end all of the knife world either.

And two years isn't very long. I've been a member going on 15 years and I came in during the latter years of greatness of this place when there were literally the best knifemakers and pioneers of the craft actively participating and sharing here daily.

There did, in fact used to be pictures and posts of these things. Where they are now. ....i have no idea. Just because you haven't seen them in your two years here means nothing.

Ever been to a custom knife seminar? Forging demo? Hammer in? Stuff like this happens on the regular at such events. I've personally witnessed two different makers at different hammer-ins using 52100 and 1084 to cut through a 3/4" bolt and then immediately slice newspaper cleanly. I have pictures and videos somewhere.....trapped in an old virus-locked laptop.
 
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