toughest steel in a folder

PatriotDan said:
I have experience of S-7 and the SR-77 (most likely S-7 with special heat treat eventhough some want you to believe otherwise)...
...Out of stainless steels I'd have to go with S30V with Paul Bos heat treat. It seems close to S-7 but not quite.
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I don't know who would be saying that SR-77 isn't S-7 since the Scrap Yard folks themselves has said it is.

In terms of impact toughness, resistance to shock, etc., S30V really couldn't be much farther away from S-7. If you are looking for that kind of toughness in a stainless, you'd do better looking at the 420 and 440A area--not superlative edge holders for extensive cutting but far more abuse-resistant than S30V or any of the other high grade stainlesses, though still nowhere near their non-stainless brethren.

I'm surprised nobody has yet mentioned the folders that John Greco was turning out for awhile (and may have a few left of, though I don't know). The 8670 steel he used for them is, for all intents and purposes, an L6 clone. His factory edge geometries for those folders verged a bit toward splitting wedges, though they always came sharp. I have a couple of these, both of which have had their edge bevels significantly raised/thinned and the improvement to cutting ability is substantial. Word of warning, though--as can be expected of L6-ish steel, the machineability is low so reprofiling takes effort. Hard to imagine much tougher folders, though.
 
:o :o :o

Heh---honestly, I really did do a thread search for the word "Greco" but apparently I misspelled it because yes indeed there it is clear as day. :D

Oh well, let me just second the Greco endorsement, then!
 
robertmegar said:
A point to consider. If the blade is tougher than the handle,the handle will break (or snap shut on your hands) before the blade breaks. Ouuuch!!!! If the blade breaks first, the failure is away from your hand.

What is the intended purpose of this knife?
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Yeah, i realize this...I can see a bevy of bad situations that could occur with a knife that is more likely to break the handle/pivot/lock than the blade. But I was trying to point out the absurdity of thinking there are knives out there with such capability. I mean, benchmade has tested their axis lock to 2000 lbs/in breaking strength? thats nuts. Whats the breaking strength of G10 reinforced with titanium...its gotta be incredibly high. I dont see any <.15" thick blade being capable of these kinds of strength.

That said, there are also dangers in breaking the blade of a knife and cutting whatever is in the path of the blade.

The intended purpose is EDC, but I've just broken knife blades (tips) in the past and dont want to break one on a $100 knife and not be able to get it replaced.

Everyone who keeps suggesting 420hc, please stop. It's not a tough steel, any way you cut it. I broke one and I wasn't even bearing that hard on it. in fact, I wasn't even prying.
 
therulebookman said:
Yeah, i realize this...I can see a bevy of bad situations that could occur with a knife that is more likely to break the handle/pivot/lock than the blade. But I was trying to point out the absurdity of thinking there are knives out there with such capability. I mean, benchmade has tested their axis lock to 2000 lbs/in breaking strength? thats nuts. Whats the breaking strength of G10 reinforced with titanium...its gotta be incredibly high. I dont see any <.15" thick blade being capable of these kinds of strength.

That said, there are also dangers in breaking the blade of a knife and cutting whatever is in the path of the blade.

The intended purpose is EDC, but I've just broken knife blades (tips) in the past and dont want to break one on a $100 knife and not be able to get it replaced.

Everyone who keeps suggesting 420hc, please stop. It's not a tough steel, any way you cut it. I broke one and I wasn't even bearing that hard on it. in fact, I wasn't even prying.
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Boss, if you broke a 420HC blade, you don't want a D2 or S30V blade. I know it may be hard for you to believe based on your previous experience, but 420HC is actually tougher than D2. (oh, and if that blade you broke was a Buck, I bet if you sent it back to the factory they would make it good. They are that kind of company.) I think we are into that blade geometry business we spoke of earlier. A thin blade will break easier than a thin blade. Sounds to me like you want a robust blade geometry, not just a robust steel.

A pretty robust shape is the Buck Strider knife in 420HC. If you were to break that one, I would eat it, blade and all. Darn, I'm getting this KaBar Large Dozier for Father's Day, and it looks really robust and Wunderful, but I haven't carried it yet, so I can't recommend it. (The Large Dozier is a new design and I've not read any reviews of it yet. The Small Dozier has been well received.)
 
therulebookman said:
Everyone who keeps suggesting 420hc, please stop. It's not a tough steel, any way you cut it. I broke one and I wasn't even bearing that hard on it. in fact, I wasn't even prying.
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That's fine, but don't imbue other steels with properties they don't have just because you don't like 420. It's far from my favorite either, but if you're looking for a more abuse-absorbing blade, BG-42/S30V/ATS-34 are not going to be your hero. Don't believe me? Drop Paul Bos a line and ask him. It sounds to me like the one you had was suffering from either a HT or geometry issue, or perhaps both.

Like I said, if you really want toughness, the stainless steels just don't compare with their rusting brethren.

Edit to add: Okay, redundant post but that other one wasn't there when I started. ;)
 
Well this thread has left me confused. For a camp knife or a soldier's knife I'd be best served with a 420 or a 440a knife? I have a hard time believing that but as I have no test data to say otherwise I'm not going to deny.
 
No, just that those stainless steels are tougher (in terms of breaking/chipping) than the high-wear stainlesses. There are plenty of steels much tougher than these that will also outperform them in other areas. Sticking to folders as was the genesis of this thread, the 8670 tool steel (essentially L6) steel used in the Greco knives is easily more robust than 420 or 440.

The reason that the 420 Buck/Strider fixed blades were brought up was, I believe, just to give an example of where a manufacturer chose NOT to use ATS-34 or BG-42 (S30V was not really on the scene yet at the time, though it would have been an equally poor choice) in a large stainless fixed blade knife. They'd have been even tougher in something like A2, O1, etc. but Buck doesn't produce much that isn't stainless, unfortunately.

*Or, at least, I think it's unfortunate. ;)
 
So Strider's use of S30V in it's whole line of fixed blades is poor choice for their intended use?

Added to say: Strider would be better of with 440A or 420, considering their knives are intended for very hard mil/leo use and are often referred to as sharpened prybars?
 
I appreciate your patience on this.

I wonder if you can help me further to understand what to look for. What in the following data says about properties such as strength and toughness of the steel in question if heat treated properly?

(This one is 1095 carbon steel)

Physical data:
Density (lb / cu. in.).......................................0.284
Specific Gravity.............................................7.86
Specific Heat (Btu/lb/Deg F - [32-212 Deg F]).....0.107
Melting Point (Deg F).......................................2760
Poissons Ratio................................................0.3
Thermal Conductivity.......................................350
Mean Coeff Thermal Expansion...........................6.7
Modulus of Elasticity Tension.............................30
Modulus of Elasticity Torsion..............................11

Mechanical Data:
Temper...................68
Tensile Strength.......139
Yield Strength..........84
Elongation...............97
Reduction of Area.....18
Rockwell.................C31
Brinnell....................293
 
PatriotDan said:
So Strider's use of S30V in it's whole line of fixed blades is poor choice for their intended use?
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You've apparently managed to miss (somedays I wish I had) the overwhelming number of threads on the subject.:D
A search using the term "Strider" and the member name "Cliff Stamp" will yield you days upon days of reading on the subject.;)
PatriotDan said:
Added to say: Strider would be better of with 440A or 420, considering their knives are intended for very hard mil/leo use and are often referred to as sharpened prybars?
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Well, that is a debate unto itself. Striders are pretty robust (think geometry per Knarfeng's comments above) and have a superb heat treat, so I don't think there's a problem with the use of S30V. I would personally, however, choose a carbon steel over a stainless steel for a "sharpened prybar" type fixed blade any day.

Regards,
3G
 
Well Cliff would only saturate me with remarks of having discussed this subject in full detail 10 years ago in rec.knives and would make references to Landes book mit messer auf deutsch. And that this has all been discovered 100 years ago in a small german town and we're just reinventing the wheel here. I'd also probably see a lot of words like bias, lie and smokescreen...

but I'd just better not go that route... ;)

(No pun intended of course...)
 
Originally Posted by PatriotDan
Out of stainless steels I'd have to go with S30V with Paul Bos heat treat. It seems close to S-7 but not quite.



What experience proved to you that S30V with Bos heat treat is close to S7 in toughness? Please tell us what knives you used and what you did with them. If it isn't based on experience, please give us your source.
 
Keith, saying S30V is close to S-7 I'll take back, no problem and replace it with S30V's the toughest of stainless steels when properly heat treated and excellent hard use knife is designed around it. I think S-7 is leaps and bounds ahead of the competition considering easily available steels.

And that's not a scientific comment. I am only a subjective user, not a scientist. My experience comes from the military circles. Many people here disagree with me on S30V anyway. I'm just not seeing 420 or 440a superiority in hard use knives anywhere. They're practically all S30V if stainless is used.
 
Buck Strider ML/FB is 420HC
Kabar Next Generation is 440A
Randall stainless knives are 440B
SOG uses AUS6 in several fixed blades
 
Yes, because S30V was marketed extremely successfully as the greatest, superest, wonderfullest, most mind-blowingly awesomest steel that the world had ever seen, regardless of intended use or size/geometry of knife; and it was touted as such in the months before its release by a large segment of the knife community before they had ever tried a knife made out of it.

The notion that this is true is about as naive as believing that a single size and power of engine could be ideal for a powering a sports car, a minivan, and an industrial dump truck---but many people embrace it nonetheless. The great advantage is that many (if not most) people don't put their fixed blade knives to much use at all, especially the expensive ones. And yes, Striders are tough, and that has everything to do with their blade geometry. With edges as obtuse as that, you won't see chipping in most realistic knife use, regardless of steel type used or hardness---it just doesn't cut very efficiently.

Don't get me wrong, it is a good steel, but it really is not the best steel for a hard use fixed blade, and not even the best stainless steel.
 
hardheart said:
Buck Strider ML/FB is 420HC
Kabar Next Generation is 440A
Randall stainless knives are 440B
SOG uses AUS6 in several fixed blades
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One thing to remember is that if we look at lower cost knives with stainless steel blades then there's definitely no S30V there.

Here's some more hard use knives:
Becker Extreme BK-77 S30V
Spyderco Manix S30V
All current Striders S30V
Chris Reeve Green Berets S30V
AlMar Sere S30V
Gerber LMF II 12C27
Of course, then there's the KaBar Extreme in D2.
And Kershaw Outcast was D2 I think?
Fallkniven uses VG-10 laminate I believe.

D2 is not real stainless I know.

There's variation there for sure but I suppose we could ask why Spyderco chose S30V for Manix? Why Strider exclusively uses S30V? Why Bill Harsey speaks so highly of S30V? Crucible still says it's tough. Joe Talmadge says something like it's as tough as A-2 right here on this site in the steel faq. Doug Ritter thinks it's tough and uses it for his survival knife, fixed and folding. Hinderer thinks it's tough and uses it in his xm-18 folder that he says is gtg for prying too. The list would go on I think if I was to continue digging. I have seen Cliff's comments and they're not favourable of S30V.

But why did not these bladesmiths choose 420 or 440a for such hard use knives? Would it not allow them to sell more cheaper and better hard use knives?

But but. I'm just a user. I'm no expert. There has been only one knife maker or manufacturer here making comments as far as I recognized. I'd like to hear them chime in.

I'm definitely looking forward to tests and data on 420 and 440a in hard use.
 
t1mpani said:
And yes, Striders are tough, and that has everything to do with their blade geometry. With edges as obtuse as that, you won't see chipping in most realistic knife use, regardless of steel type used or hardness--it just doesn't cut very efficiently.

Don't get me wrong, it is a good steel, but it really is not the best steel for a hard use fixed blade, and not even the best stainless steel.
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My Strider EB-T has edge angle of 45 degrees and my KaBar has 47 degrees. I agree most knives meant for cutting only have smaller angles.
 
So Patriot Dan,
Spyderco and other premium chose S30V for the same reason that we blade people look for it. S30V has excellent edge retention and good toughness for that level of edge retention in a stainless steel. And most descriminating knife people, myself included, place a premium on edge retention.

But if it came to pure toughness, and remember that was the original question, 440A and 440B would outperform it. That is why big stainless blades (over 6" long) are usually made from 440A or 440B, not S30V or D2. And of course t1mpani is correct, non-stainless is in a whole other league.
 
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