toughest steel in a folder

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therulebookman

Joined
May 10, 2007
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I'm interested to see what people think is the toughest steel in a folder. When I say toughest I mean the technical definition: highest SHEAR YEILD. In other words: hardest to break. Edge retention aside what knife do you own that you just can't break no matter how hard you try?

If you want to give your thoughts on fixed blades thats cool too, but IMO INFI pretty much has to win since over in the busse forum they say only 2 have broken.

I also think that fixed blades are just designed to be stronger from a materials standpoint and that alot of makers don't try to put tougher materials in a folder because they don't think they can be made strong just based on principle.
 
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) by Scrapyard and they are very, very tough SOBs. I have no idea why folders aren't being made out of them. Probably due to their lack of edge retention or something...folders don't excel in tasks requiring tough blades anyway.

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.
 
my emerson commander has pryed on a few things with no wories. IMO the axis style and frame lock is the best setup for a lock. a good temper process is also key.
 
I'm not sure technically what steel has the highest shear yield that is used in a folder, but I'll bet there are a number that have a higher SY than the lock and handle materials. So, isn't it a moot point, since "a chain is only as strong as its weakest link"?
 
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) by Scrapyard and they are very, very tough SOBs. I have no idea why folders aren't being made out of them. Probably due to their lack of edge retention or something...folders don't excel in tasks requiring tough blades.

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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Do any production makers use s30v with paul bos heat treat in a folder?
 
therulebookman,

many manufacturers use S30V.

Strider uses Paul Bos heat treat. Paul Bos used to do their heat treats but moved elsewhere and left the process for Strider to use. I don't know if it was licensed or what, I don't have the details to tell but rest assured, it is in all practicality Paul Bos heat treat. Striders are way tough!
 
PatriotDan said:
therulebookman,

many manufacturers use S30V.

Strider uses Paul Bos heat treat. Paul Bos used to do their heat treats but moved elsewhere but left the process for Strider to use. I don't know if it was licensing or what, I don't have the details to tell but rest assured, it is in all practicality Paul Bos heat treat. Striders are way tough!
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If I could afford a strider, It would be "stride"ing around in my pocket right now. LOL
 
I know the feeling... and once you break the piggy bank you'll be permanently broke cause you keep needing your Strider fix.
 
therulebookman - The Buck Mayo TNT is made with S30V that is heat treated by Bos. They are available from Ira Woods for around $150.00 and are very nice knives.
 
Cabelas has the Buck 110 in Bos S30v, (Alaskan Guide). Better get them while you can only a few made. Just got mine for $72.0 and that's with shipping and handling.
 
therulebookman said:
Do any production makers use s30v with paul bos heat treat in a folder?
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I read somewhere the Paul Bos is the largest source for heat treats by any knife manufacturer. I don;t know if that's true or not, but I know Benchmade uses them, and some other major reputable knifemakers that I can't remember to name right now. Buck I think, like someone said. Probably a ton of others that are mentioned daily here on BF.
 
I just picked up a spyderco caly 3 in zdp 189 because of all the rave reviews on the hitachi steel.
Admittedly its the sharpest factory edge ive ever seen on any knife but Ive yet to see how long it will hold this edge.
carbon scales are nice though :)
 
i'd also have to say S7, though it's rarely seen in folders - S5 or H13 might be even tougher, and behind that (all else being equal) 5160 and L6. It would be fun to see the "sharpened prybar" philosophy applied to a folding knife, where the pivot tends to fail before the blade steel (I think Extrema Ratio's folders are about the heaviest duty in production, and they use N690 stainless, which i have seen do really well in flex-tests....)
 
Low alloy carbon steel is usually tops, regardless of whether it’s fixed or folding.
Good 420HC should do nicely if you want stain resistance.
(I still prefer high alloy steel any day of the week though.)
 
Joshua J. said:
Low alloy carbon steel is usually tops, regardless of whether it’s fixed or folding.
Good 420HC should do nicely if you want stain resistance.
(I still prefer high alloy steel any day of the week though.)
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Yeah, this is bad advice, IMO 420HC is one of the worst steels, talking toughness or edge retention. My buck adrenaline had neither as it was a sharpen every week knife (EDC) and I snapped the tip off without even prying. Just about turned me off to buck altogether. I am considering a 154CM buck strider though.

And to add to my original question: Is D2 the toughest steel in a folder? I know its not as tough as alot of fixed blade steel such as 5160, INFI, s7, etc. but they dont stinkin make folders in those steels.

I agree with hara-kiri-yogi gimme a sharpened crowbar folder. I think this is kind of the approach of Strider and Hinderer though, Hinderer seems to indicate prying with the XM-18 is a good idea. So why can't someone make an XM-18 knock off in a production facility to cheapen it up?
 
therulebookman said:
I'm interested to see what people think is the toughest steel in a folder. When I say toughest I mean the technical definition: highest SHEAR YEILD. In other words: hardest to break.
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If you want shear strength, make sure it's really hard. And since shearing strength is so dependent on cross section, just make it really thick, and pretty much any steel will do. A thick piece of crappy steel will have more strength than a thinner piece of uber steel.

"Toughness" is not the same thing as "strength". In fact, by the technical definitions, they're about opposite.

Several guys are bringing up the shock steels, which are known for their impact toughness. This is not the same thing as strength.

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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Going by the numbers, I have never heard of any stainless steel that could come anywhere close to the same toughness league as the shock steels, at least at knife hardnesses. Both may have good strength, but if you want to see the difference impact resistance makes, give 'em both a couple good whacks with a hammer and report back. ;)
 
therulebookman said:
And to add to my original question: Is D2 the toughest steel in a folder? I know its not as tough as alot of fixed blade steel such as 5160, INFI, s7, etc. but they dont stinkin make folders in those steels.
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In your original post you said you were not talking about edge retention, but rather a steel that is hard to break. For that you want a lower carbon content and will need to give up some on edge retention. Toughness and edge retention are opposites. The rule of thumb is that to get more of one, you have to give up some of the other.

D2 is one of the best for edge retention. But not good for el destructo work. 440A would be much tougher. Won't hold an edge real well, but it would be tougher.

If I wanted a combination of pretty good edge retention and pretty good toughness, I'd look at AUS8. If I wanted to go tougher than that and get less edge retention, I'd look at AUS6 maybe even AUS4. CRKT has some of their blades in these steels. Maybe one of the M16's.

Remember that blade shape is also going to play a part in the perceived toughness. A thinner blade is going to be damaged more easily than a thicker one. I just got a KaBar Large Dozier in AUS8. The blade is 0.155" thick. That'll take quite a lot of hard work. Think the CRKT M21 also has a very thick blade in AUS8 also.

Anyway, you're looking at the wrong steels in D2 and S30V if you are looking for pure toughness.
 
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