M2 vs. The World?

Jan 10, 1999
I have been evaluating an M2HSS AFCK for a few months now, and no other blade among the current league of high-tech "tactical" production folders comes close to its combination of edge holding and toughness. I compared the M-2 AFCK to an ATS-34 AFCK and a Spyderco CPM440V Military for edge holding, toughness, sharpenability, and corrosion resistance.

This quote was made by Steve Harvey on the BM website. My interest in it is the way BM is starting to push this "new" knife steel. The actual steel has been around for some time, but I don't remember anyone using it for blades before BM.

My question to you (all) is: What do you think would be the response for a model 710, 4" Axis Lock, with M2 HSS? Given what Mr. Harvey has to say and the evidence he presents, wouldn't this be the ultimate tactical folder?

I think a good tool steel will always outperform a "normal" stainless, even the better ones like ATS-34 and VG-10 (for the record I do like ATS-34, just not as hard as BM treats it). Whether the particle steels can compete remains to be seen - I respect Mr. Harvey's opinion, but 440V is only the first of them to see production use, and from what I understand it's far from the best of this new breed.

The reason folders aren't usually made in tool steels is because they have working parts and lots of nooks and crannies for moisture and corrosive substances to lodge in. Benchmade has decided to risk this by coating their blade with a substance that supposedly protects even after it wears off. Whether this will prove effective or be a great disaster remains to be seen; This will be a long-run effect, and M-2 AFCKs haven't been around in great numbers for long enough.

I for one would love to join in the experiment, but I have a few knives on my list before getting a new version of a knife I already own. Also, I am pretty fluent in the disassembly of Benchmades, warranty be damned, and feel I could effectively keep such a piece clean. How will customers who leave their knives intact fair? I think for this model (well, for all of them, but especially this one) Benchmade should be encouraging disassembly of their knives, not seeking to prevent it.

As to your final question, I think if the M2 knives can resist corrosion then an M2 710 would indeed be a fine "tactical" folder. The ultimate? For my own $0.02 I'd still prefer the speed and shape of the AFCK, as I feel its lock is up to every reasonable expectation.


(Why else would a bear want a pocket?)
I know that RJ Martin used the M2 on some of his knives, he's trying a lot of different types of steel right now.


When a fellow says, "it ain't the money but the principle of the thing,"
it's the money.
F. McKinney Hubbard


M2 is an excellent steel, provided you maintain it properly and heat treat it precisely. Cryo is A MUST, as well as MULTIPLE tempers (at least 3). My experience with it is that the edge degrades slightly from scary sharp, then, stays at that level for a long time.

RJ Martin
RJ --

Does BM do it right then? I don't know how the manufacture the M2. When you say that the edge degrades, I figure that to be the case with any steel. Are you saying that it can never be resharpened back to a "scary" edge? Please clarify. Thanks.

M2 now huh?

M2 is designed to withstand the types of high heat that drill bits (often made of M2) commonly encounter. A temper at 1150 degrees will give it a hardness of 59-61. So, unless the guys marketing these knives include asbestos gloves so one can experience the full, high temperature working range of a knife made of M2, it is a waste of time to make any knife out of it. D2, O1 or any of the other simpler high carbon steels will do just as good (if not better) a job as M2. The type of complicated and specific heat treatment M2 requires will NOT produce qualities that make it more effective as a knife steel. It isn't magic, just designed to do a specific job which didn't include cutting rope, skinning carcasses, or dispatching villians.

Don't believe the hype.
While I would like M2 over ATS-34, I don't think as a HSS its main advantage is one that is particularly important to knives as fenixforge has noted. Its no surprise that is outperforms several stainless steels, however.

Ek, can you give me a link to the entire commentary by Steve? I would not be surprised to find M2 having better wear resistance and toughness than ATS-34, and better toughness than CPM-440V. But CPM-440V should be miles ahead in terms of wear resistance. I would like to see M2 compared to 3V, which has twice the charpy value when both are tempered to give equal wear resistance, and CPM-420V as it is a direct improvement over 440V.


[This message has been edited by Cliff Stamp (edited 23 May 1999).]
I don't think M-2 was as clear a winner in this article as this thread makes it appear:

"I have not been able to determine a clear winner in cutting and edge holding between the M-2 AFCK and its stainless steel peers [the ATS-34 AFCK and the 440V Military], but in terms of toughness, it is in another league altogether."

In reading the article for the umpteenth time, I realized that in addition to the statement above (edge holding similar between all three), Mr. Harvey relates NO conclusive toughness test between M-2 and 440V, only between M-2 and ATS-34. So effectively he says that M-2 cuts as well as 440V and it is unknown how its toughness compares. Certainly it is no surprise that he found Benchmade's ATS-34 more brittle, but I would be surprised to see similar behavior from Spyderco's 440V.

Just wanted to point that out.

As long as they're risking corrosion anyhow, why not just make the AFCK in 52100? That might outperform all of the above steels, and certainly be the easiest to sharpen.


(Why else would a bear want a pocket?)
I am sure of one thing here. Kabar is coming out with what is a radical knife for them in four blade shapes. The blades are in D2. I am sure that the statement about M2 being the best in toughness and edge holding is about to be challenged by this new knife. I myself prefer edge holding and believe that for most of use users that is the more important of the two. I am not about to chop or do any heavy prying with a folder. Thus 440V in mine is a better choice. But going by toughness and edge holding I believe the D2 Extremes or
The EdI's with A2 blades will give M2 a very serious run. IMO M2 is as over rated as the AFCK and Benchmade as a whole.


Tom Carey
At similar hardness, I don't see A-2 giving M-2 a run in the edge-holding category. How hard is EDI going to make the A-2, anyone know?

What defines hardness in blade steel anyway? Is it the elements in the steel or the heat treat that account for a "hard" blade? I thought that M2 was the hardest steel avaialable.

Lastly, does hardness = toughness?


Hardness is its resistance to peening or other deformation (not breaking) by force. A Rockwell testing machine drives a much harder point into a substance with a known force, and the depth of penetration reveals the hardness.

While hardness is affected by the elements in the blade, it is really determined by the heat treatment. Before the tempering portion of the heat treat, even steels like 440C are in hardnesses much higher than any steel blade in production (I beleive Rc in the high 60s). The tempering process brings the blade down to a more reasonable hardness, where it is far less brittle. ATS-34 became popoular not because it could *reach* a hardness of 60Rc or so, but that it was not unusably brittle at that hardness (though that's debate-able). Similarly, M2 is not able to be harder than any other steel per se, but is able to retain good toughness when harder than most.


(Why else would a bear want a pocket?)
Steel isn't inherently hard. It gets hard due to the heat treat. Some alloying elements contribute to hardenability, and thus some steels have the potential of being harder than others. However, just because a steel is hardenable, doesn't mean the maker will leave it very hard. You also have to have acceptable toughness at that hardness. In the heat treat, after hardening the blade, there is typically a tempering process, which lowers the hardness and relieves internal stresses. The maker will lower the hardness to one that gives him the tradeoff he wants of toughness versus edge holding.

Hardness is not toughness. The commonsense view of hardness is: if A can scratch B, then A is harder than B. In knives, the Rockwell process is normally used, as described by Corduroy. There are several types of toughness, but you can think of them as resistance to breaking/chipping under stress.

The Rockwell hardness of a blade does not completely describe the abrasion resistance of that blade. So if two different steels are at hardness 60 Rc, that does not necessarily mean they will have the same abrasion resistance (or toughness).


[This message has been edited by Joe Talmadge (edited 24 May 1999).]
As many others have already stated, hardness of a blade does have much to do with the heat treatment. But, the composition of the steel also plays a major factor.

If you want to talk about a steel that has a lot of potential for high hardness after quenching, then look no further than good old W2. By comparison W2 quenches out at 67-68, M2 quenches out at 64-66, and 440C at 58-61. But, hardness is only one small part of the picture, since most finished blades need to fall within the 54-60 range (via tempering).

I agree with Corduroy: if we are going back into the realm of highly rustable tool steels (M2 has no chromium) why not use some 52100 (or D2, or 01, etc). At least D2 contains 12% chromium. The only thing that M2 has that the others don't have is tungsten which allows it to withstand high temperatures.

I think that people are trying to build/create a mystique around M2 that just isn't there. It would be much more fruitful to spend time and money testing the limits and production feasibility of the new stainless steels that are being created.

IMO, the best knives for overall working performance (disregarding corrosion resistance) are those forged by an experienced and knowledgable bladesmith. But, given the obvious limitations of high production knife companies, this type of process is rarely an option.
fenixforge, when it comes to steel composition and heat treat, I must bow to your superior knowledge. But, that being said... I thought tungsten was harder, more abrasion resistant at any temperature, not just a higher temperature. {*concern, confusion, distress*} [nah, not really, but curious.

Work hard, play hard, live long.

[This message has been edited by Outlaw_Dogboy (edited 24 May 1999).]
Great topic, guys..
Been hoping someone would bring up the topic regarding M2 steel.

When I ordered my AFCK-M2, I wrote to Benchmade, and asked them how can I be sure that my AFCK is really M2, and not just ATS34 that's been remarked.

Guess what they responded to my question?

One engineer jokingly replied "Soak it in water overnight. If it rusts, then it's M2."


I thought they claimed the BT2 coating would protect it from rusting? Dunno if the joke was a joke or not.

Anyway, keep it up people! This is really getting to be interesting.


PS. Maybe someday someone would come up with a test on different grades of steel on folders, with regards to their strengths and weaknesses, and destroy the myth once and for all.

Err... According to Steve Harvey's article, M2 has a chromium content of 4%??

Yeah, according to my chart from Spyderco it's got a content of 3.5-4.5% Chromium. It's still a far cry from a stainless, but actually a bit higher than other "tool" or "carbon" steels.

I really think that the "rust test" described in the article and by Benchmade is bogus. Tapwater or rainwater has very little corrosive ability at normal temperatures and conditions. Try getting some blood or seawater or Coca-Cola in the pivot area and leaving it for a few days - then you'll see what sort of real-world corrosion risk a tool steel runs in a folder.

Also, finish and temperature counts for a lot. When grinding ATS-34, I will have seen rust spots for in a matter of minutes because the steel is so rough and the water is very hot. When that same knife is mirror-polished and at room temperature, I could leave it in a glass of water for days and not see anything like that. That's why I can't stand bead-blasting - no need to pit a perfectly good knife.


(Why else would a bear want a pocket?)
Here's my spin on the whole deal.

I was lucky enough to work at a heat treating plant a few years ago when I first became interested in knives. I am no guru by any means, but I did observe a lot of about different types of steel.

The tungsten that is in M2 (6.5%)is put in it to help it withstand heat when you are drilling a hole in something. That is why tunsten is also used in certain light filaments and welding electrodes. It melts at a higher temperature than any other known metal. Yes, tungsten carbide is very hard, and is used for super hard cutting tools and abrasives but it is also very brittle. I can't remember how many times I have had a HHS (M2) drill bit snap in situations where I was applying a normal (or less) amount of pressure. To me, this type of brittleness is unacceptable in a knife that I carry.

Besides, the type of hardness that pure tungsten carbide provides (68-70 C) is way above the level that is necessary for a using knife. You start getting into the same problem you encounter with ceramic and flintknapped obsidian knives. Yeah, they will cut about anything, but if you drop them, game over. In other words, any gains in hardness you get from tungsten is negated by the brittleness it brings with it. The type of hardness one needs in a knife can be easily obtained from simpler carbon steels.

As far as the chromium content goes, my chart from Lindberg Co.(a relic from the heat treatment gig) shows M2 to have zero chromium. Perhaps somone has added some chromium to M2 to make it look more suitable to knife enthusiasts. But, if they did, then I guess it isn't really M2 anymore.