12C27 vs CPM-440V

Griffon · Feb 19, 2001

Executive summary: 12C27 won in this case, which perhaps surprisingly was a case where edge holding was important.

It began when I wanted to remove the diamond patterning on the handle of my F1. The CPM-440V knife was an obvious candidate for that, as the cutting involved slicing through lots of tough material (I took just a little at a time, as I didn't want to cut away to a lower level than the rest of the handle).
After that, the knife was totally dull and wouldn't slice paper cleanly and the like, something it'd done very well before.

Last week I wanted to give my Fällkniven S1 the same treatment (as I've started to use it more). I thought it would be a good idea to use my EKA Nordic W11, as I wanted to dull it in order to see how it resharpens. (Yes, it's got a longer edge than the CPM-440V knife, but about in proportion to the S1's larger handle.)
To my surprise, it wasn't dulled to any noticable degree.

To have been truly scientific, I should of course have done one side of each handle with each knife and at the same time so that practice couldn't have improved my technique. But I don't think that'd done much of a difference. Maybe I should also have had the edges ground to the same angle, but perhaps not, since they were about the same subjective sharpness [as in slicing paper cleanly and force required to cut strings].

Hypothesis: For this[?] material, steel hardness is what makes a difference.
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Bart student · Feb 19, 2001

True.. CPM440V is Much more brittle then 12C27.. The tough plastic could have broken off small pieces of the CPM440V edge, while it could only bend pieces of the 12C27, only at a microscopic level off course.
12C27 is often scoffed at, but in my opinion it's right up there, along with ATS-34, compensating it's lesser edgeholding with it's much greater toughness.
12C27 is one of those steels I'd like to see more, for example in larger bowies, like the trailmaster.

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Joe Talmadge · Feb 20, 2001

This is interesting! What 440V knife did you use?

Joe

Burke · Feb 20, 2001

Wouldn't surprise me if what Bart student says is essentially correct; while the 440V may be more wear-resistant, it is less resistant to lateral stresses, resulting in the blade being more damaged by cutting at an angle.

dogboye · Feb 20, 2001

Can't say that I'm surprised at all. In fact, I'm surprised by the continuous statements of incredible edgeholding attributed to 440V (S60V).

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iktomi

Griffon · Feb 21, 2001

Originally posted by Joe Talmadge:
What 440V knife did you use?

A Starmate. So when I think about it, I guess the edge length/surface area comparision isn't exactly fair, as it's partially serrated.

dogboye · Feb 21, 2001

Don't the serrations add edge length? Thus giving the S60V Starmate an advantage, theoretically, in edge holding?

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iktomi

Cliff Stamp · Feb 21, 2001

Is this one of the ~55 RC 440V blades? If so you would expect it to be significantly weaker than blade steels in the 59-61 RC range. Therefore the edge will roll much quicker. After you do the cutting do a simple steeling and see how much the edge is restored, the closer it is brought back to 100% the more you say rolling and not wear (or fracture) as a cause of blunting.

If it is once of the 59-61 RC 440V blades then just lightly run your thumb nail down across the edge or check it under a scope (even light mag like x20 will do) and check for fracture as Bart indicated as a source of the problem.

-Cliff

Paracelsus · Feb 21, 2001

I was surprised (really meaning shocked) to find that ABS Mastersmith PJ Tomes uses Sandvik 12C27 in his kitchen knives and no frills folders. He says he uses that steel because it is very good edge holder, and is very tough compared to other steels when given his heat treatment. He is sort of legendary for pulling out his daily carry with a 3.25 inch long flat ground 12C27 blade and Prying with it (opening paint cans) to demonstrate its toughness.

For stock removal knives he finds the toughness of 12C27 is superior in a working knife. He also makes knives with 420V (I have one of those) for much greater cost (more difficult to finish well). But he will not use 440V because it is too brittle at working hardnesses.

It it is good enough for PJ, it must be a great steel

Paracelsus

Griffon · Feb 22, 2001

Originally posted by rockspyder:
Don't the serrations add edge length?

Usually, yes, but I didn't use them much this time.

Originally posted by Cliff Stamp:
Is this one of the ~55 RC 440V blades?

I don't know, but it's certainly not brittle. Didn't think to save it after this cutting and it wasn't recently I used it, so it's too late to check it now.

dogboye · Feb 22, 2001

Paracelsus, do you have a 440V knife as well as that 420V Tomes folder? If so, how do you feel the 420V compares to the 440V?

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The most affectionate creature in the world is a wet dog. - Ambrose Bierce
Most dog owners are at length able to teach themselves to obey their dog. - Robert Morley

iktomi

Cliff Stamp · Feb 22, 2001

Paracelsus:

He is sort of legendary for pulling out his daily carry with a 3.25 inch long flat ground 12C27 blade and Prying with it (opening paint cans) to demonstrate its toughness.

That demonstrates strength not toughness, which is kind of ironic as 12C27 is not as strong as most cutlery stainless steels like ATS-34 (basically for the same reason it is tougher). In regards to flex, which might be the point (see how much this blade bends), all steels will be able to take a large flex if they are ground thin enough.

I had a fillet blade from Phil Wilson, 420V, 59 RC, distal taper, 10" long, 1/8" stock. I could bend the blade until it took a perm set. This does not indicate great toughness. This blade is not as tough as the CPM-10V blade I have (chips out easier) which I cannot bend in such a manner (the 10V blade has a thicker grind).

The thinner the steel the less shear the steel will feel across the bend because of the smaller difference in the curvature radius between the inner and outer surfaces.

-Cliff

Bart student · Feb 23, 2001

I have a spyderco starmate, plain.
It holds an edge good, but the knife itself is build as a fighter, a very thick blade.
If you wanted to cut an apple, it's simply the wrong knife. You will need to put much more force on the blade to go trough.

On the other hand, I have several laguioles in forged 12C27. They are always tapered from 3 mm at the pivot to the point. They may hold an edge worse technically, but they do cut better. In a daily using situation, a one-hand laguiole would be tops.

I really don't understand the obsession of USA-made high-quality production knives with thick blades. Opinel uses a forged 12C27 variant in some (other are forged 440B) stainless variations. Off course, they're not fighters, but let's face it folks.. the size of the "tactical market" suggests 75% of us are SEALs.

CPM440V will not allow a grind like a opinel or a laguiole, simply because it is too fragile.

12C27 is, as I said, a seriously overlooked steel, with qualities found in no other steels. And is the hardness is too soft for you, try the razor-blade version, 19C27. 1.15% carbon, basically a Sandvik version of 154CM, and I think much purer. I'd like to see someone test this steel VS BG-42... I think suprising results will occur.

If you wanna test the steel, get a Perceval P-60. Excellent auto, perfect steel. That blade is 2.5 mm thick. I heard no complaints of people breaking it yet, because if you break it, you'll know it was your own damn fault.

greetz, Bart.

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J D Wijbenga · Feb 23, 2001

Interresting toppic. I see I am not the only one who thinks CPM440V in an unbalanced steel. Good wear resistence, but difficult to resharpen and prone to chipping at the hier RC's.

I am interrested in 12C24. It sounds like a better balanced steel.

Bart,
Could you tell us more about the P-60? Does it have goood (=thin)edge geometry? Does it have a reliable lockup? Does it have a clip? ect. Thanks!

Paracelsus,
Does have P.J. Tomes have a website? Do you perhaps have a picture you can post of his no frills folders? I am always interrested in what knifemakers make for themselfs. Thank you.

Cheers,
JD

Paracelsus · Feb 23, 2001

Cliff, allright, so you think PJ's little demo means nothing, and you may be right. However, he does not use 12C27 for no reason. He likes it much better than ATS34. PJ strives to make Using knives. If he chooses 52100, 420V, and Sandvik as his primary steels, I'm sure there are plenty of good reasons for those choices. But I should not try to speak for knifemakers.

Rockpyder, I have No personal experience with 440V. I do like my 420V knife. I have asked a number of makers about 440V and almost all of them have shown a preference for 420V compared to 440V. I am sure 440V is a good steel, like many others, but the word on the street is that 420V is better. No Cliff, I have no data to back that claim up. But if you ask around, I am sure you will hear the same thing.

Paracelsus, terminologically challenged

Paracelsus · Feb 23, 2001

Sorry, no web site for PJ. KnifeArt carries some of his knives from time to time. www.knifeart.com

aerius · Feb 25, 2001

Strange thing happened today while working at the bike shop. I was using my Kershaw Ricochet (440V) to cut some rubber elastomers for a bicycle suspension fork when I somehow rolled the edge. I was cutting the elastomers on top of a wooden workbench, the first couple slices went through like nothing, but the next cut "hung up" and made a mess of the elastomer. I took a look at the edge and saw that the section that was hitting the workbench had rolled, but I was able to straighten it out reasonably well on a screwdriver shaft. after this cutting was almost as good as before, but the edge rolled again after a few more cuts so I quit and switched knives. I did the same thing with my Benchmade 710 (ats-34), but was unable to cause any edge damage even when I deliberately cut hard through the elastomer and into the workbench. I'm working again on Tuesday, and will conduct further "tests" while the boss is on lunch break.

SNiPER · Feb 26, 2001

I say CPM440-V (now know as S60V) kills 12c27.

But I think that the Sandvik is very under rated. Its very good for an everday knife that does not get abused alot. I think it holds an edge very well. I have a Delta Z Tactical that has the Sandvik 12c27. I first thought that 12c27 wasnt good at all, but after getting this knife, it changed every thing. It has held an edge better than any ATS-34 of 154cm knife I have ever owned (Emerson, Benchmade, and some hand mades).

On the other hand. S60V can take a really good beating and still hold an edge well. The only down side is that the steel is hard to get on a low cost knife. Sandvik is also hard to find, but can be seen on lower cost knives. By low cost I mean under $120 or so.

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Bart student · Feb 26, 2001

Hello Dutch forumite,

Yes, the P-60 has a clip, and not such a simple thing as a BM clip, a William henry style clip.
It's steel is 19C27, About like BG-42 (in my opinio even better). The blade is fully flat ground, about 2.5 mm thick. simple form drop-point.
Makes a cute sound, a 'sigh' when opening. Most succesful French auto ever build.

You can mail me for pics and more info, yes, preferably in dutch.

greetz, Bart.

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J D Wijbenga · Feb 27, 2001

Thanks Bart and Paracelsus, and Bart there will be a mail in your mailbox.