s30v

[Cliff Stamp]

Yes Cliff did write that, because that is a clear statement of the results of the testing the guy did on Messerforums.

Note clearly this does NOT say that the wear resistance of 420HC is superior to S30V. What it proves is that wear resistance is not the critical factor in the edge retention of the cutting they performed as S30V was INFERIOR to 420HC.

-Cliff

 

[gator68]

Note clearly this does NOT say that the wear resistance of 420HC is superior to S30V. What it proves is that wear resistance is not the critical factor in the edge retention of the cutting they performed as S30V was INFERIOR to 420HC.

Yes, Jerry misquoted you the first time.

I am simply annoyed that Jerry chooses to call anyone who's testing disagrees with his ideas "unreliable", ie a liar.

 

[olpappy]

Jerry is not the only one, I'm sure many readers will be confused after reading the articles referenced by Cliff. The results of that testing seems to go against the popularity of high carbide stainless steels over lower carbon choices with regard to edge retention. Wouldn't the CPM steels with finer carbides have less of a problem with carbides falling out of the edge?

It sounds like most here can agree that S30V is tougher than other stainless steels but not quite as tough as some of the non-stainless steels. It might make a fine 7-9" knife where edge retention and corrosion resistance are wanted, but you might want something else to make a machete. The real big surprise here for me is the question of whether 12C27 or 420HC could be better than S30V in edge retention!?

Slightly off topic, I just got a kitchen knife in S30V, the previous owner told me it was great and holds an edge forever. As far as I know it was only used in the kitchen, but the edge showed multiple tiny chips. He had never sharpened the knife, it had the original edge bevel which the maker had put on it. I sharpened it with waterstones to 10,000 grit, it definitely was harder to sharpen than other knives, and I was not able to get a real "mirror" polish on the bevel, although it is now sharper than any other knife I own.

I have sharpened this knife to a very low angle. Only time will tell if it will chip, but will the experts here tell me if they recommend a microbevel or some other different sharpening for S30V as compared to say, Aogami blue steel or VG10? What hardness are most people heat treating S30V to?

 

[Cliff Stamp]

Yes...

I was not implying you had this stance either, just clarifying it.

The results of that testing seems to go against the popularity of high carbide stainless steels over lower carbon choices with regard to edge retention.

Yes, as there is much hype and little fact in that area.

Wouldn't the CPM steels with finer carbides have less of a problem with carbides falling out of the edge?

No, this is one of the greatest areas of hype. The arguement ignores that the steels have so MUCH carbide that the P/M process does not produce finer carbides. The carbides in 12C27M are MUCH finer than those in S30V. Many properties are also based directly on carbide volume, Crucible themselves notes this in their patent articles. They state for example THEMSELVES that since carbide volume is one of the main factors in reducing toughness then using vanadium carbides instead of chromium carbides will increase toughness at a given wear resistance level because less vanadium carbides are needed. Note how Jerry opposes this generalization in the above claiming WITH NO FACTUAL basis at all that you can not predict based on microstructure and specifically carbide volume in spite OF THE MEASURED FACTS with prove otherwise.

It sounds like most here can agree that S30V is tougher than other stainless steels but not quite as tough as some of the non-stainless steels.

The first statement is nonsense propogated by some makers. There are many stainless steels far tougher than S30V.

The real big surprise here for me is the question of whether 12C27 or 420HC could be better than S30V in edge retention!?

Yes, this is MEASURED FACT not subjective opinion.

-Cliff

 

[Jerry Hossom]

Gator, how could I misquote Cliff when I used a cut and paste of what he said?

As with most of what Cliff tries to refute above, I've quoted his own writing then he argues with what I quoted. The Buck Solution review from his own website clearly states the blade was used and chipped when received, there is no mention of a carpenter or carpentry tasks, and the blade ultimately broke after being abused in various ways and by driving it into a piece of spruce, standing on it, then hitting it with a hammer - not common carpentry tasks here in GA anyway.

Are there really photomicrographs which show 12C27M and 1050 have the same microstructure?

Does the laboratory model (Landes or the inormal one shown on Messerforum) represent how steels actually behave in knives? If they support that 420hc has better edge retention than S30V, I don't believe the models accurately reflect how steel knife edges are shaped and work. If someone thinks they are better served with a blade in 12C27 or 420hc than in CPM-154, they should be happy with $10 knives. If I owned such a knife I'd be happy to sharpen it, drive the edge through an 8d nail and show the pic. Or, those of you who do can try it for yourself.

Let me point out that contestants in the Professional Cutting Competition use high carbon (~1% C) steels. CPM-M4 (1.4% C) blades often win, as do blades in O1 (0.9% C). If you read through the site you'll see that the competition challenges a knife edge pretty thoroughly. It must be extremely sharp for some of the cuts and still be tough enough to cut through materials like hardwood dowels.

http://www.cuttingcompetition.com/


Olpapy, I use Rc59/60 for my S30V. I don't use high performance kitchen knives (I use a Henckels Professional), because I don't want to have to sharpen them. With the Henckels all I do it hit it with the steel everytime I pick it up and it's good to get me through one meal which is all I want. (Maybe it's 12C27M. Wouldn't that be a kick in the head?) I would probably put a microbevel on that edge, but I put convex edges on all my knives which accomplish pretty much the same thing.

 

[gator68]

Gator, how could I misquote Cliff when I used a cut and paste of what he said?
...

This all dodges the point that anyone who states something you don't agree with is called a liar.

I don't really care about whether the sniper school "endorsed" the Buck Solution or whether they just handed out knives to graduates.

I do think it is wrong to call Possum and Cliff liars because they say they can cut a nail with a knife, when you can't. Maybe it is your testing that is "unreliable" due to bad technique. As noted in this thread, cutting nails with a knife is an old parlour trick used to sell knives and shouldn't be a problem with most knives.

Possum has posted video of himself cutting through a deer's neck in one swipe. If he says he did it with an old knife, I'd believe it.

That German guy posted results from cutting tests on tons of knives that showed a SAK outcutting all of the S30V knives. Rather than calling these tests "unreliable" you might try thinking about the tests themselves and what the tests mean.

 

[Cliff Stamp]

Gator, how could I misquote Cliff when I used a cut and paste of what he said?

Because what you CONCLUDED was incorrect.

The Buck Solution review from his own website clearly states the blade was used and chipped when received, there is no mention of a carpenter or carpentry tasks, and the blade ultimately broke after being abused in various ways and by driving it into a piece of spruce, standing on it, then hitting it with a hammer - not common carpentry tasks here in GA anyway.

The relevant section :

"On harder woods there were durability issues. The solution was chopped into 5/8" thick birch, and torqued to the side which left a huge piece of the edge in the wood. This was repeated breaking out another large pice. The penetration into the wood was fairly low, as the handle ergonomic issues prevented serious swings. For similar reasoning it wasn't heavy torque, just wrist rotation. "

The primary grind was destroyed at this stage by very light work which is common in carpenter at the framing level (taking apart existing work for reconstruction). Here is a reference picture :

Those huge circular pieces are what came out in the light wood working. The fact that the edge was chipped initiall is completely not relevant. It was also clearly noted in the review. I thought these were in the review. THey are in the thread here, I will update the review on the cite later with a few pictures.

As for the qualitative work you mentioned. As I noted many times, the reviews consist of quantitative and qualitative work. Of course you need to look at the CONCLUSIONS which are drawn to judge the tests. I have done nail cutting myself and concluded it is useless because I can do it with any knife if I am careful enough. You on the other hand imply that it is some sort of meaningful test which is nothing but HYPE.

I am the one pointing out the limits of what I have done. You are the only spreading conclusions with no FACTUAL support which contradicts MEASURED FACTS by many independent sources.

Are there really photomicrographs which show 12C27M and 1050 have the same microstructure?

Well if you looked at the C/Cr diagram that Verhoeven noted you would see the carbon content in solution is the same (tolerances) and thus the austenite will behave that way in regards to hardening (with the expected effects of Cr in preventing the diffusion forming, i.e. pearlite).

Of course it depends on how they were heat treated. You can leave as much of the Chromium carbide in 12C27M in the austenite as you want. But ideally it is designed to run with almost none as it will lie almost on the saturation line and thus have the hardness you would expect with the given carbon in solution.

Anyway like I said, read Landes book or just call him. I have, he will actually educate you if you want.

Does the laboratory model (Landes or the inormal one shown on Messerforum) represent how steels actually behave in knives?

Yes, that was why it was developed because the CATRA tests do not. Again if you read the book or called him you would know this already. What is your resistance to learning?

If they support that 420hc has better edge retention than S30V, I don't believe the models accurately reflect how steel knife edges are shaped and work.

Of course because the experiment does not support your theory. The reality is you do not understand what they did or why it is superior because you do not understand what edge stability means or what properties influence it and what it means in regards to use.

The guys on the forums did physical cutting on rope BY HAND. It was not artifical in any way. What they saw was DIRECTLY in agreement with what Landes measured and is the same thing Johnston saw when 1095 easily had better edge retention than ATS-34 in his knives when tested by working people, tradesmen, cowboys etc. .

Let me point out that contestants in the Professional Cutting Competition use high carbon (~1% C) steels. CPM-M4 (1.4% C) blades often win, as do blades in O1 (0.9% C).

How much of the carbon in 52100 is in the austenite, I will give you a hint, it is the same as a stainless steel I mentioned which rhymes with 12C27M. Here again you show a complete ignorance of understand of even basic issues of heat treatment, judging the performance of a steel by the level of carbon and ignoring the amount of carbon in the austenite and in the carbides. This is what is critical to performance as it will determine the wear resistance and the responce to quenching.

In REALITY, both of them have the same amount of dissolved carbon (0.52 for 12C27, and 0.055 for 52100 at the ideal austenite soak temperatures), and the same resulting hardness (which you would expect as it is mainly correlated to this - FACTS again). Do you really want to continue to argue one has a really weak edge prone to deformation and you would be ashamed to make a knife from it and the other is just extremely excellent? You want to cite ANY FACTS to support that claim at all.

How about 1050-1065 and similar steels? HOw are they going to be so excellent in regards to edge strength when 12C27M is so poor because it only has 0.52% dissolved carbon? Is it because the carbon steels are american?

-Cliff

 

[olpappy]

Thanks for the advice, Jerry. This is sure a controversial subject, S30V seems to be the Charles Darwin of the knife world. Hundreds of years after the Scopes Monkey trial there are still folks who argue about it.

The scientific way to approach this would be not only to read what Landes says, but also to try to independently confirm his results. How about head to head testing of 3 identical knife blades of S30V, 420HC and 12C27, made by Jerry, Phil Wilson and Roman Landes? The knife design should be built with specific criteria, for example a small hunter expected to do skinning, occasional camp chores, and have edge retention, some degree of toughness and also strength. Or, a combat knife expected to withstand impact, prying, in addition to all the above qualities. Testing for those qualities should be appropriately matched to the knife design. Abusive tests which exceed the limits of what users would really expect such a knife to do should be viewed as just that, testing outside of normal use. Each maker can heat treat, temper, quench etc. to bring out those qualities best in the particular steel, but they would have to agree on a common design in terms of blade length, grind type, thickness behind the edge.

What tests will be performed needs to be discussed and agreed upon ahead of time by both the makers and the testers. That way the makers will know what the blades will be used for. Again, tests should take into account what the blades are expected and not expected to do. Testing could be done by Cliff, Jerry, and a third party similarly experienced in testing, but all 3 must agree to do the same tests, the only variable being their technique. Blades must only be identified by color or a number assigned to them. Nondestructive tests like cutting rope could be done as a passaround, with each tester sharpening each blade to their preference when they receive it. Destructive tests like longitudinal or lateral stress could only be done once, so would have to wait until nondestructive tests are completed.

Testing like this seems to be a good idea, if we really want to independently confirm what their research is saying. I have heard good things about 12C27 on the forums, can anyone direct me to any info about 420HC, besides Phil Wilson's site? Seems like corrosion resistance was one of the main reasons he was using 420HC, apparently he has "upgraded" (his words) to cpm154 now instead. (http://www.seamountknifeworks.com/about.htm) So, does anyone here feel like telling him that cpm154 is inferior to 420HC?

 

[Kohai999]

Do you like S30V for anything, and if yes, what configuration, preferred applications, grind, hardness and thickness?

Best Regards,

Steven Garsson

 

[bruce]

Moodino, no need to be sorry just because you don't understand the test protocols of the Army. The Army has "several" very well run activities that stand alone and provide very valid, "third party" data and results. Now I'm not saying "all" Army testing and evaluation has been squeeky clean (Sgt. York weapons system), but several independent test activities (one is the Tradoc Combined Arms Test Activity) generally do a good job. In my day, no hand waving, just well gathered and processed data. It is up to General Officers (two stars and above) to make the decisions.

In my present job as a manager of R&D for a large frozen food company, I get better results (read: closer to what the public is actually thinking) than if I employ a market research company that can't design a test properly. Oh, they can design proper tests but without a firm knowledge of my industry, their test designs don't get at the way things really are. I've never been to a test run by a "retained" third party test company that wouldn't have failed in execution if I weren't there to correct some of their procedures.

Your statement seems correct in theory but not in practice.

 

[Kohai999]

I have heard good things about 12C27 on the forums, can anyone direct me to any info about 420HC, besides Phil Wilson's site? Seems like corrosion resistance was one of the main reasons he was using 420HC, apparently he has "upgraded" (his words) to cpm154 now instead. (http://www.seamountknifeworks.com/about.htm) So, does anyone here feel like telling him that cpm154 is inferior to 420HC?

Phil used to be one of the main proponents that Cliff quoted, but since he has shifted to CPM154, Cliff simply does not cite him anymore concerning 420.

If you go here:

http://www.bladeforums.com/forums/showthread.php?t=421773&highlight=phil+wilson

you can see that Phil ran cutting tests in late 2006, and the 12C27 was the least effective cutter(90), and the S30V(210) was most effective.

I do want to do more work with 12C27, AEB L and others. They are simple, easy to work with and make nice blades. I think they would be great for kitchen knives. However the reality is that CPM 154 seems to do everything they do and a little more and I get great tech support from Crucible and I can get the steel in any size and quantity I want in 5 days after I order it.


PHIL

Best Regards,

STeven Garsson

 

[hardheart]

Phil Wilson's posts are an excellent example of the economics of selecting blade steel, and the price/performance a maker and customer can expect. He uses different steels for different applications and properties, and discusses it openly. Heat treat and finishing are very important to the maker, in the time and equipment they have to invest in. Just that he found 420HC to be a proper steel in his line, plus the abundance of it in Buck knives, should be enough for most knife users to understand it is an acceptable steel in the right role. But then he found the performance boost in CPM154, with an easy heat treat and it polishes up nicely. I know I like my CPM154 knives, and they feel a lot better in sharpening than the old 154CM production knives I had.

He also has done head to head rope cutting tests with his own knives in a variety of steels, have a look on the testing board, olpappy.

 

[db]

Here is what Roman Landes has to say about carbides and edge stability. As very few edges are polished to a 6000 to 10,000 finish and under 12.5 degrees per side I think it is a non issue for many. Note, he also says this has been known in the US for many years.

2 the mentioned "scary sharpness" for me personally beginns below 1µm of edge radius
3 this kinda sharpness can be reached with good equipment such as japanese waterstones (Grit 6000-10000) and a propper strop and good skills
4 At these levels of sharpness u will find a clear manually detectible difference in the sharpening behavior and the edge stability within differnt types
of steel (e.g. O1 vs D2)
5 Large carbides tend to chip while grinding when the edge has a low angle 25° and below see pic of ATS 34, page 55 Abb. 22 in my book
6 These large carbides are prone to fracture since they do not have a elastic stable matrix around to absorb sideloads in use.
7 small carbide steel O1, AEB L do have the same behavior on a level about 50 times smaller since carbide sizes are that much smaller
8 With improper mechanical properties due to bad HT carbides can be torn out of the compound while grinding, wo beeing positioned on the edge.
Finally u get the ledeburitc steel sharp for average use and they fit well to slicing cutting action.
Whereas scary sharpness that can be reached with steels like O1 , AEB L can be reached by "Monster-carbide-steels" at the edge parts where there is only
a low volume of small carbides inbetween the segregation lines of the large ones.
The stability of this kinda edges (whitch is the core of edgeholding) is due to these facts very different.
High sharpness to hold for longer is dedicatet to small carbide sizes and fair volume fractions of carbides (O1, AEBL)
So for future discussions one has to bare in mind, getting sharp is one thing hold this level of sharpness that can be reached (edge stability) is another.
BTW: Almost all of these facts have been figured out by scientists with the beginning of the 20th century in Germany, Japan, Russia, GB and US (see literature
list in my book)

 

[the possum]

Thanks for the vote of confidence, gator.

A thin F. Dick butcher knife can easily snick through a smaller deer's neck if it's been skinned. And it's probably only around .015" thick or so at the ed... Well, like I said, I ain't measured the edge; just comparing it to my pocketknife from memory here.

Possum, I don't really know how to respond to a claim that you chopped through a deer neck with a blade that had an edge only 0.015" thick without any effect to the edge. I guess I'd have to see it.

Well guys, since my integrity is being called into question here, when I got home I measured the edge geometry of that old butcher knife. And I gotta say, I really aught to refrain from posting until I have taken an actual measurement, because just guessing from memory, I was in fact wrong about the edge thickness. It is only .010" wide at the top of the edge bevel. (about 33% thinner than I thought) The edge bevel is .021" wide, and if I set the caliper jaws at .015", they slide .051" up onto the blade; clearly well past the edge bevel. The spine is basically 1/8" thick, and the blade is about 1 ½" wide (1.466") up on the belly. All measurements taken in the end third of the blade where the bone chopping took place.

possum, flesh isn't difficult to cut through but the bone is an interesting result. Could you cut through the forelegs?

Didn't try to; I was already done with the legs at that point, but I am rather certain the edge would have been damaged horribly if I tried chopping them dynamically. But thanks for asking; this is another one of those (big) details that Jerry doesn't seem to care about. Leg bones of deer are much, much harder than the ribs or spine, but on other critters I haven't seen as much difference. Well, lemme rephrase that- there is still a difference in the hardness, but leg bones of smaller critters are still nowhere near as hard as a deer's. That's why I'd like to know what lamb leg bone is like. BTW, if I tried chopping them at the spongy part near the joints, or carefully chopped them while firmly supported on a chopping block, I may have been able to do so without damage if I wanted to brag up a parlor trick.

 

[Jerry Hossom]

OK, I guess I've been away too long and too many things have piled up for me to respond to. Possum, I'd still like to see the cut and the edge detail afterwards; that said I've never cut deer neck bones so maybe they're easier than I would think. The leg of lamb cuts were made with the leg suspended from a rope. The same with the beef shank cut mentioned earlier. Beef leg bone is VERY hard as you probably know. Now what are the details I don't care about?

It would appear Phil Wilson's experience is similar to my own. Ironically, I have a sheet of 420HC in the shop where I've been planning on making a couple machetes with it one day. It should be good for that for tropical use. I personally don't like S90V because I think it's a little brittle, but that could just be my take on the kinds of knives I make. It might do very well for moose and bear hunters who need a lot of wear resistance.

Cliff, try this. If 1050 and 12C27M have the same microstructure, where does all that Chromium in the 12C27M hide? Also, is any of that Chromium in the form of carbides and if so how can the matrix still retain the same amount of carbon as in 1050?

Why do they add alloying elements to steels to make them stronger? Is strength a component of edge stability. Are plastic deformation and strength related?

I'm still trying to sort out what Landes is saying there. If I understand it correctly, scarey sharp starts below one micron and you need a small carbide steel to get there and for the edge to be stable at that level. You can do it with large carbide steels but only if the carbide size distribution is correct, which is of course what CPM's are all about, but even then the edge won't be as stable. I have to think those are too few facts from which to draw conclusions. What about strength? What are the stresses that dull the edge and make it less stable?

The carbide size in M60S was 0.01 microns, and you could indeed get that steel scarey sharp. It also did well on the CATRA test. You just couldn't hit anything hard with it, because even at Rc60 it would suffer terminal plastic deformation.

I still say, you gotta cut the nail...

Hey Possum, cut the nail and show us a pic. I'll need to see the steel smear on the side of the edge though.

 

[hardheart]

I thought they treated to have free chromium for stain resistance and not to have lots of chromium carbide. I might be remembering wrong also, but I think the finer steels had better matrix micro-hardness results, and hard equaled strength.

 

[Jerry Hossom]

Hardheart, did you just make that up?

 

[hardheart]

nah, I'll have to do some searching to find it though.

edit-well, the chromium thing isn't hard to track down. Just the idea of having free chromium to create an oxide layer to resist corrosion. I was vaguely thinking of the use of high austenizing temps to dissolve the chromium carbide. Seems from Crucible's page that they like vanadium so much in part because it is a stronger carbide former and leaves the chromium free while getting those really hard carbides. And apparently carbon combines with 17 times its weight in chromium. I'm no metallurgist, but this stuff is kinda neat. I'll see if I can find something about the micro-hardness tests...

 

[hardheart]

heh, here's one that would go with the FFD2 thread on the testing board, http://cat.inist.fr/?aModele=afficheN&cpsidt=15098461
the finer grain structure increased the hardness. *continues googling* man, everything is in pdfs I can't open, but here's an abstract from another paper on that site

Two commercial thermomechanically controlled rolled (TMCR) microalloyed steel plates have been used to investigate the relationship between the duplex ferrite grain size distribution and local fracture stresses. Statistical analyses of the grain size distributions were performed for the fine and coarse ferrite grains in the two steel plates. Microhardness values were measured for each grain size region and it was found that the fine grain areas have significantly higher microhardness values than the coarse grain areas. Tensile and blunt-notch slow bend tests were carried out over a range of temperatures on samples from the two commercial TMCR steel plates. The local fracture stress (σ[F]) values were calculated and the results show that the σ[F] values are almost independent of temperature. The presence of a mixed grain size distribution results in significant scatter in the local fracture stresses of the steels. The distribution of fracture stress values can be correlated to the coarse grain size distribution in the steels examined.

 

[Cliff Stamp]

Also, is any of that Chromium in the form of carbides...

It can be reduced to the minimal amount, beyond measurable, <1% carbide, the rest of it is in the matrix. It depends on the austenization temperature/time. Of course the chroimum in the matrix will lower the performance of the steel outside of corrosion resistance, hence why it is limited to ~5% in the tool steels. This of course is nothing inherent abotu 12C27M. The same issue is with all "stainless" steels. But in the above I was speaking of edge stability and in that case since the hardness and carbide volumes are nearly identical you will have the same class of steels. Note in Landes work how both stainless and non-stainless are in the same general classes because of precisely this reason. Again, read the book, ask the guy to explain if you do not want to take the time to translate a few sections to understand the graphs.

If I understand it correctly, scarey sharp starts below one micron and you need a small carbide steel to get there and for the edge to be stable at that level.

You can get there with fairly high carbide steels, in general as long as the abrasive is hard/sharp enough. There is some difference, but is is REALLY small. I have run trials on sharpness testing on chisels for Beach and there are differences in steels but I can just barely say they are significant (0.05 p-value). I do not think a carpenter would say one is sharper initially because the changes are just so small, but they do have significant differences in edge retention. THe high carbide (or high retained austenite) steels will take chunk blowouts while the fine one will wear smoothly in comparison.

You can do it with large carbide steels but only if the carbide size distribution is correct, which is of course what CPM's are all about, but even then the edge won't be as stable.

Carbide volume tends to be more important than carbide size. RWL-34 and ATS-34 for example are not significantly different in terms of edge stability, this was a surprise for me at first until I looked at the pictures closely and did a few intersection lines. RWL-34 is just basically an average of the wildly scattering ATS-34 edge stability measurements. Some ATS-34 edge sections have the huge carbides while others have almost none, in contrast RWl-34 has a much more consistent intersect volume. 12C27M has a much higher edge stability than the P/M steel, RWL-34 because the carbide content is too high - P/M or not. Here is an example of the tearout :

This is from Landes book "Messerklingen und Stahl". Now quite clearly. Imagine a steel without those huge carbides compared to one which had them. Which one is going to hold a very thin and polished edge better. Just look at the composition of the tool steels which are designed for fine cuts like F2, M2, etc., they do not have huge chunky carbides for this reason.

-Cliff