Toughest steel

[dogboye]

Originally posted by rdangerer
Now that, folks, is true dedication to furthering the range of materials available for one engaging in stock removal.

No kidding! You can count on Jerry to be one of the ones always pushing the edge of the envelope!

 

[tallwingedgoat]

1V might be pretty tough. But it looks to be an air-harding metal that wont react well to diff hardening.

I still don't see how anything can beat a water/oil hardening steel like 5160, 6150, S-5 etc, at 30 HRC with a hard edge.

 

[allenC]

Man, you guys are talking way above my head.
Still, I have to ask: when it comes to knives, which steel is the toughest but is still easily sharpened by your average knife-nut?

Allen.

 

[contender]

In my humble opinion, INFI, is the best and toughest steel out there today that can still be relatively easily sharpened by novice knife nuts like me.

INFI comes from Busse Combat. Check them out. They make their own steel and as much as other knife makers would love to license it, they only use it on their own knives.

 

[rdangerer]

Originally posted by tallwingedgoat
1V might be pretty tough. But it looks to be an air-harding metal that wont react well to diff hardening.

I still don't see how anything can beat a water/oil hardening steel like 5160, 6150, S-5 etc, at 30 HRC with a hard edge.

This brings up a point that I've wrestled with a bit.

Differentially heat treated blades no doubt make superior crow bars/pry bars, as the soft spine could take a real tensile bend out to something radical like 60-90 degrees, and spring back to "close" if you were lucky. Problem is, I don't much care about such performance, since I wouldn't do this with a knife unless it was some true survival situation, and I actually needed to pry something in this manner (escaping from a downed plane by prying fuselage apart? I dunno... hard to comes up with another legit use). I.e., wouldn't 1V be "PLENTY tough enough" in pry-bar mode even super-normal tasks if uniformaly heat treated to Rc57-58?

The reason most people want "tougher", at least to my eye, is so that the actual working edge and the tip/point are "tougher". As mentioned earlier, resistance to micro and macro chipping during chopping type use, and resistance to gross deformation due to "edge rolling" would be desireable but different facets of toughness.

Chipping is reduced when materials have greater impact toughness.
Edge rolling resistance is mostly related to hardness, I think, but could be influenced substantially by edge angle.

And there's the rub: something like 1V can be hardened to a relatively hard number (Rc57-58), while really having a very high impact resistance (resistance to chipping). You would expect a 1V blade to far exceed the impact toughess at the edge at a given hardness, say Rc58, than what you could achieve at the edge on 5160, 6150, 1095, etc. And usually, toughness and hardness on the edge and in the tip of the knife are far more interesting than overall knife tensile strength in pry-bar mode. Well, to me anyway.

 

[Cliff Stamp]

rdangerer :

Edge rolling resistance is mostly related to hardness, I think, but could be influenced substantially by edge angle.

Yes, hardness is highly correlated to strength in a linear manner (alloy playes a roll as well) but the changes in steel hardness from blade to blade are not nearly as radical as the changes in edge geometry, and since strength is proportional to the square of the dimension in the direction of the applied force, edges gain strength very quickly with increasing thickness. For example a blade at ~50RC at 1/4" thick is far stronger than a blade at ~60RC that is 1/8" thick [similar primary grinds, and steels although the latter won't actually change the outcome in this case as the difference in cross section is too extreme].

You would expect a 1V blade to far exceed the impact toughess at the edge at a given hardness, say Rc58, than what you could achieve at the edge on 5160, 6150, 1095, etc.

Yes, exactly. A really tough spine does little to help the edge when it has to take a hard impact. In regards to prybars, while the differential tempered blades can take more flex, they are easier to get there, take a set at a lower angle, and have less spring back than a fully hardened blade. The biggest advantage they have is absorbing really heavy shock like hitting the knife with a metal object or a large rock to drive it through something. Or to be able to handle times of extreme stress / panic when you will push a blade past the elastic point. However really tough steels like 3V tend to have a decent plastic region before they rupture so you would need to be really out of it not to notice the blade was going to break, long past the point where it stopped being useful as a pry bar.

-Cliff

 

[dahong_palay]

cutting ultra-hard steel? use hydraulic jets. this taiwanese guy (dunno his name) sells these compressors with adjustable nozzles, built-up pressure and cutting media. using a spray of compressed air, he could cut dry material like paper like the stuff isn't there. with compressed water, he can cut fabric, meat, veggies. when the water is mixed with abrasives, he can cut steel and even glass.

 

[Epsilon]

I believe very seriously in differentially hardened blades. However it depends on the blade. For any utility knife I make, I use a full harden and full temper. For my fighting knives and swords I always use a differential hardening. The reason is simple. All my utility knives are small, they will never see the impact and shock my swords will. To differentially harden a utility knife does not seem logical.