Spyderco CPM440V Rockwell?

Joined
Apr 27, 1999
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Sal & company, What is the hardness on your 440V blades. I've got the Starmate, but I'm also wondering about the Military and Blade Forums special Native. --Thanks
 
Jeff - Actually, we've lowered the Rc to 55/56. We find that we get greater strength AND better edge retention at the lower Rc.

sal
 
Thanks for the info Sal; however those sound like awfully low numbers. Could you give some test numbers that indicate things that improved? How do the numbers compare to ATS55?

What kind of failures would you get at higher rockwell? I would guess chipping and maybe tip breakage. Do you think that the powder technology super alloys give very different rockwell readings than traditional steels?

When did you make the change to 55-56 rockwell? I just bought a Starmate (I believe it probably left Spyderco within the last month). Would it be at the old (higher) or new (lower) rockwell?

[This message has been edited by Jeff Clark (edited 06 October 1999).]
 
I just checked the spyderco.com website and it still indicates 59-61 Rockwell for the Starmates. It seems like a good idea to get that changed.
 
I can't remember where I read it, a steel reference manual, I believe, but, someone wrote that CPM440V was at it's best at a Rockwell in the mid 50's. Better edge holding, tougher, heightened ductility, etc.
Seemed a little odd when I read it because all the reading I'd done up to that point seemed to equate higher hardness with better performance, to a degree.

Of course this is flawed thinking because of all the variables involved, different alloy's attributes, intended use, and so on.

Anyway... Sal I'm glad to here that you've done this. I have the utmost confidence that you and your R&D dept. are striving to get the absolute best performance that a particular alloy has to offer.
I wouldn't expect anything less from Spyderco!



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The individualist without strategy who takes opponents lightly will inevitably become the captive of others.


 
Blind faith, ie., "it has to be the right way because Spyderco is doing it that way.", is never a good idea.

In regards to it being better at 55 RC. It would have a much great impact roughness, and ductility. The strength, wear resistance and probably bend fracture strength would however be lower.

I would be very interested if 440V at 55 RC outperformed VG-10, ATS-34, etc., at 59 RC. And at just what it outperformed it doing. I can see it having better abilities in some areas, but also falling behind strongly in others.

-Cliff
 
I'm a bit disappointed in finding such a low hardness. I bought my knife thinking it was up at 57-59 and I would get great edge holding ability. After all, I bought it because it was 440V and was treated to this level...or so I thought that is what I read in the advertisements. If it is truly this low, I doubt that it will be any better than some of the other ATS-34 knives that I have at about 59RC. Can anybody verify this? I haven't tested this claim...I haven't had the knife but 2 weeks. I guess I will need to be a little skeptical about the ad slicks from Spyderco next time...although I can vouch for the quality of the knife.

jj
 
There is a rather easy way to judge the quality of edge holding. Take your Military and some knife you think has good edge holding ability and cut a bunch of cardboard. Use really hard fast rips and you should see any difference becoming significant very quickly.

-Cliff
 
>If it is truly this low, I doubt that it will be any better than some of the
>other ATS-34 knives that I have

I wouldn't rush to judgement until you test the blade versus an ATS-34 blade. Rockwell numbers don't tell the whole story about wear-resistance when you're comparing two different steels. 440Vs wear resistance is supposed to come from the large number of well-distributed vanadium carbides, and I've heard plenty of reports saying that even at 56Rc it outperforms ATS-34 for wear-resistance.

Definitely worth a test, let us know what you find out if you actually try it. Be sure to start out both edges at the same edge angles and coarseness.

Joe
 
Don't forget the staple test
smile.gif
(darn, where's Outlaw Dogboy with all this talk about his favorite metal).

Can someone point me to a chart (was it Crucible?) that cross-refs RC, toughness, strength and wear-resistance? Most charts (including Linder) just shows RC ranges ... OTOH maybe such a chart doesn't exist.

Possibly you can compensate for poor toughness by honing a less aggressive edge (I think this was brought up before)?
 
Thanks Cliff. I noticed ATS-34 is conspicuously absent ... mostly a comparison of D2, 440C and 440V. Too bad, maybe a more comprehensive chart doesn't serve the interests or needs of the mfgr.

Doubtless that the figures will support 440V's superiority in wear resistance... ie, it'll cut more paper between sharpening than many other steels. I guess whether it's "better" or not depends on whether that's all you do with it, since it may have, as you speculated, "better abilities in some areas, but also falling behind strongly in others".

Since I don't chop a lot of wood (or run into a lot of staples), I'd have to say that my BF Native works for me. But all this discussion is useful to know the next time I wonder about using my knife on that screw....
 
Cliff,
I don't subscribe to "blind faith" very often, but then Spyderco has shown time and again that they want their product to be the very best it can. Witness this in their presence on the Forums. They continually show a high regard for consumer input and frequently update and upgrade their product line with performance and safety being high priorities.

You are correct, of course, in that putting "blind faith" in a manufacturer can be wrought with peril and dissappointment, however, from what I've seen with Spyderco and their product line I personally don't mind showing a little "blind faith".
In my mind they have earned this right, with their overall commitment to excellence, and the way they follow up with that commitment.

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The individualist without strategy who takes opponents lightly will inevitably become the captive of others.




[This message has been edited by misque (edited 08 October 1999).]
 
In the general knife forum, JoHnYKwst commented:

"Spyderco heats treats their ATS-34 blades at ~59HC, and their 440V blades at ~56-58HC, and just recently lowered the hardness of their 440V blades to ~55-56HC. Even with the 440V blades having such a low rockewll hardness, Spyderco had to modify their serrations because the 440V blades were more brittle than the ATS-34 blades."

Is that the answer? Is Spyderco running real low 440V hardness to accommodate serrations? I didn't buy my Starmate with serrations (and never would). Has the performance of my knife been compromised for a feature it doesn't have? Is Spyderco making their plain edge knives with heat treatment optimised for serrated edges?
 
Jeff, this shouldn't surprise any of us that anything that reaches the consumer is a result of a host of design compromises, especially in a production item.
 
Note that the trend in recent "super" blade alloys has been away from a uniformly high hardness for maximum edge retention, and towards a softer matrix filled with an abundance of very hard particles. Admittedly, this loosely descibes any steel, but new "exotic" materials like BDC and Talonite seem to carry the concept to extremes - the concept being that as the matrix material wears away, new carbides are exposed, giving a continuously fresh, aggressive edge. If this works well for "exotics" like those above, why might it not also work for 440V? Its makeup gives it radically more carbon than any "normal" steel, which makes me think that a fairly soft but carbide-rich matrix might be achievable on a scale not previously seen.

That's guesswork - what isn't guessing is what Spyderco does. They test an abundance of blade materials at various hardness under uniform, controlled conditions. Admittedly, this may differ from "real world" usage, but it's the industry peak in terms of removing the "user variable" and establishing a reliable baseline for blade material comparisons. This sort of testing, followed up by field tests before a steel is widely adopted (e.g. the 440V Military or VG-10 Calypso) is the closest to "the real story" that any knife company currently offers. In short, faith in Spyderco is not "blind."

-Drew
 
Well, I finally stumble onto/into this thread, and see the infamous O_D staple obstacle test mentioned a couple of times. DOH!!
wink.gif
Just to confirm/defend myself... I don't go out and test my knives this way. But, it happened, and those were my results. I just cringe a little each time I look at the edge of my BF Native out near the tip. It is just now beginning to disappear, after 3 or 4 sharpening sessions.

Haven't had a chance to look at the page that Cliff posted above, but will right now. "I'll be back" after that.

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Sometimes you're the windshield; sometimes you're the bug.
Outlaw_Dogboy


 
Well, I took a look at the pages that Cliff referenced above. It certainly appears that the only thing that recommends a lower hardness for the 440V is the charpy test (toughness?). In a small (or even large folder), I'll take edge holding over toughness, if it means that it passes my staple test better.
wink.gif
What is the Charpy test anyway? Is there a thread out there that gives some detail on it?

I notice the CPM itself recommends on page http://www.physics.mun.ca:80/~sstamp/images/T440vpg1.JPG to harden to the lower end of the hardness range for toughness, the higher end for wear resistance. And, it seems that based on what I see there, Spyderco is going for the bottom end of the hardness range. I can understand better in a large fixed blade, but just how tough does a folder have to be? Interesting thing: it looks like page http://www.physics.mun.ca:80/~sstamp/images/T440vpg3.JPG shows D2 to be significantly better in charpy at the high end of 440V hardness spectrum. I have to say that I'll be leaning way toward D2 from now on, but I guess that is only in custom knives.

Anyway, like someone alluded to, I'm not very impressed with what I've seen in the 440V of my BF Native. I'll repeat again, though, that I love the knife, because of its ergonomics, its size, the handle, and the looks. But, like I said in the other thread, I'd like it just as much in GIN-1, ATS-55, or even -34. Please don't take this post wrong, Sal. You guys do good work. Heck, GREAT work, and have great knives. I just know now that I want a harder blade more than an exotic metal, and wear resistance over toughness (apparently). As a minimum, this has been quite a learning experience.

------------------
Sometimes you're the windshield; sometimes you're the bug.
Outlaw_Dogboy




[This message has been edited by Outlaw_Dogboy (edited 08 October 1999).]
 
My point is that I would hope that one of the design compromises made on smooth edge knives is NOT to necessarily use the same heat treat as on the serrated models. I would desire the serrated blades to go in a different run in the oven from the plain edges (at least for the expensive 440V) blades. It would allow more optimal heat treatment and would also probably improve batch yields.
 
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