What's the toughest powdered metallurgy stainless steel?

Comeuppance said:
Don't disregard physical characteristics because of the test used to demonstrate them. Abuse tests like that may not show the typical or practical use of a tool, but it does show the toughness to some degree.

If someone is asking about toughness, they don't want people cutting paper as a method of demonstration. Typically, in situations like this, someone is looking for a material that has such impressive capabilities that they never have to worry about exceeding them.

It's one of the reasons I keep eyeing the Warcraft Tanto and the Survive GSO 5 - big, beefy knives made out of unobtanium. It's hard to beat the knowledge that you are carrying something that could be hammered through a pipe without suffering catastrophic damage.
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+1 to this post
 
K.O.D. said:
I have two knives in ZDP and neither are brittle in the least. They keep an edge fo eva!
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I had 2 spyderco's in ZDP (both after the switch in HT) and both of them chipped on me during light use. The first I sent back to spyderco cause it happened 2 days after I got it (it was actually the 2nd knife I got, but the first to chip) and they sharpened it for me, the other the tip got damaged and a chip about 1/4" down from the tip during some use (at the same time) and I sharpend them out and sold both. I love me some super steels but not ZDP, I also had rust/pitting issues with it, I consider it LESS stain resistant than D2.
 
It all really comes down to the following:

  1. What will the knife be used for?
  2. What is the blade and edge geometry?
  3. How was the blade HTed and tempered?

Impact testing may or may not even matter or even be relevant depending on how the knife will be used and the knife itself.

There are a lot of variables that would have to be addressed also.

Big difference in the use that a 3" folder and a 10" chopper will see.
 
Ankerson said:
It all really comes down to the following:

  1. What will the knife be used for?
  2. What is the blade and edge geometry?
  3. How was the blade HTed and tempered?
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I like this, if by "it" you mean the type of steel to choose. The real problem is we seldom know anything about the heat treat, much less how that heat treat affects the performance of the blade. We're usually lucky to know the hardness within two or three points of Rockwell.
 
Twindog said:
I like this, if by "it" you mean the type of steel to choose. The real problem is we seldom know anything about the heat treat, much less how that heat treat affects the performance of the blade. We're usually lucky to know the hardness within two or three points of Rockwell.
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It's usually best to go with a known manufacturer with a good reputation and or a Custom Maker that can give more information based on the actual use the knife will see and steel recommendations based on that use.

But even then the edge geometry may have to be adjusted to fit the actual use.
 
evosbu1 said:
The question is kind of pointless since virtually no production companies make knives in the premium stainless steels where 'impact' capacity would even matter, that is to say, large fixed-blade bowie styles or machetes. I think Bark River makes a few 4-5 inch blades in S35V. 'Impact' isn't really a factor for a folding knife, and if it is then I know for sure that my Manix XL in S30V is all anyone could ever need.
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I would strongly disagree with "impact" toughness not mattering. Try hitting a hidden staple when cutting open a box, try hitting anything hard by accident after you went through a tip zie that required a lot of force and that force carried you through to something you didn't want to hit. I would argue that toughness is more important than wear resistance in my personal use. Maybe I am a little haphazard and don't notice the staples, or a little careless at times but I would rather just have a steel that can handle it. Nobody has any reason to hate one steel over the other except for real world experience. My experience is that S30V has had more edge stability issues than any other steel I own hands down. It is what it is, I don't dislike Crucible as a company, in fact I love me some M4 and CRUWEAR. Reason being is they are tougher and I have had no issues with edge stability. Maybe people aren't high on S30V because they are simply reporting real world results.
 
I may be out of my element here, but is there such a thing as elemental stainless steel? Just iron, carbon and chrome? Or is it made at all? and if so, is it desirable, good for use, etc.

Larry
Tinkerer
 
I would state that ALL high alloyed stainless steels have comparable toughness. There is no use to argue whether it is s30v or d2(lets count it here) or anything else.
Older stainless - like 440C will be a bit less tough.

AEB-L and similar - will be about twice as tough.

BUT it is still many times less tough than good tool steel not to mention shock steel.
 
nccole said:
I would strongly disagree with "impact" toughness not mattering. Try hitting a hidden staple when cutting open a box, try hitting anything hard by accident after you went through a tip zie that required a lot of force and that force carried you through to something you didn't want to hit. I would argue that toughness is more important than wear resistance in my personal use. Maybe I am a little haphazard and don't notice the staples, or a little careless at times but I would rather just have a steel that can handle it. Nobody has any reason to hate one steel over the other except for real world experience. My experience is that S30V has had more edge stability issues than any other steel I own hands down. It is what it is, I don't dislike Crucible as a company, in fact I love me some M4 and CRUWEAR. Reason being is they are tougher and I have had no issues with edge stability. Maybe people aren't high on S30V because they are simply reporting real world results.
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In folders impact testing has less to do with it than compression strength and side loading that can happen more often than actual impact.

The twisting and other less than ideal cutting methods that can happen cause most of the actual damage that is seen in folders.

Edge damage will happen in any knife with any steel.

It will fail in one of 2 ways.

Rolling

OR

Chipping

And there are a lot of variables that will cause it to happen either way so there aren't any set in stone answers as things can and will change due to the variables.
 
TrojanSteel said:
Here's the answer:

Assuming equal quality heat treat, the toughest stainless powder metallurgy are:
CPM-154 ~ Elmax ~ CTP-XHP
CPM-s35vn

The non-stainless (but close to stainless), toughest powder metallurgy:
CPM-3v
PD1

Here's the relevant DATA:

http://www.bladeforums.com/forums/s...-Toughness-Expansion-on-Charpy-C-Notch-Values
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Impact testing isn't really relevant unless you are talking about large choppers.

The main factor that is relevant is compression strength in smaller knives and folders, also side loading (side pressure).
 
Let's go exotic: SM-100 and Stellite 6K. Both are favorites with custom maker Tom Mayo, and have rave reviews on edge retention and corrosion-resistance. But these steels are very expensive. Alpha supply has some Stellite 6K in stock.
 
Ankerson said:
Impact testing isn't really relevant unless you are talking about large choppers.
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I disagree. Toughness counts in all but a very few, very specific knives... certainly in a general-use 6" blade. See the other examples about running into a staple in a box or a knot in a piece of wood or a bone in a chicken or...

idaho said:
I would state that ALL high alloyed stainless steels have comparable toughness.
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You would be quite simply incorrect. There are wide differences in toughness between common stainless blade steels.

My answer is CTS-XHP or Elmax, HT'ed by Peter's to 58-59Rc.

Nathan's experiments with Elmax @ 60Rc (discussed above) are very interesting, showing better wear-resistance and little if any loss in toughness. I have yet to have any Elmax run that hard but I will be giving it a go with my next batch.

Strong-Dog said:
If you consider CPM-D2 stainless, maybe that?
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I've used it and remain unimpressed; while it's not a bad steel by any means, I consider it a half-vast solution to a problem that doesn't exist. It's not really much tougher or wear-resistant than regular D2, although it does polish up much nicer and take a finer edge. It's also not stainless, fairly costly and sometimes difficult to find. If stainlessness is not a huge issue, 3V is king in my book... better finishing, better edges, and much better toughness than either D2 version.
 
nccole said:
I would strongly disagree with "impact" toughness not mattering. Try hitting a hidden staple when cutting open a box, try hitting anything hard by accident after you went through a tip zie that required a lot of force and that force carried you through to something you didn't want to hit. I would argue that toughness is more important than wear resistance in my personal use. Maybe I am a little haphazard and don't notice the staples, or a little careless at times but I would rather just have a steel that can handle it. Nobody has any reason to hate one steel over the other except for real world experience. My experience is that S30V has had more edge stability issues than any other steel I own hands down. It is what it is, I don't dislike Crucible as a company, in fact I love me some M4 and CRUWEAR. Reason being is they are tougher and I have had no issues with edge stability. Maybe people aren't high on S30V because they are simply reporting real world results.
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That S30V can't run over staples or bump concrete without destroying itself is a pretty fantastic claim. Spyderco then must be run by a bunch of idiots to offer it in all of their premium knives, right?

and "real world experience". In something as partisan as this thread I'm kind of skeptical about the variability of what that means for you.
 
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