Diamond Blade Knives

[Bors]

I was wondering if you have heard of this maker. Any chance of one being tested.
http://www.diamondbladeknives.com/frictionForging.aspx

[will york]

DiamondBlade was formed about two years ago by Charles Allen, President of Knives of Alaska, to market blades made with the "friction forging" process described on the website. The process starts with D2 steel and uses a high-speed process to "swirl" the steel under friction-generated heat along a thin segment. This results in an area that is very hard--hardness in the high 60's on the Rockwell C scale--and relatively tough for such high hardness. That "friction-forged" area becomes the edge, with the rest of the blade made of garden-variety D2 steel.

The result is high wear-resistance at the edge which puts the steel in a league with other high-edge-retention steels such as CPM S90V. The edge also develops a measure of rust and corrosion resistance, although the rest of the blade is basically just D2 which is not stainless. So basically, it's a D2 steel blade with enhanced edge-retention.

The best objective discussion I've seen of the process, and edge testing of the steel, was in the following thread on Bladeforums, which was initiated by Phil Wilson. Phil is an engineer by training, a knifemaker, and a frequent contributor to Knives Illustrated Magazine. He's also a helluva nice, honest, straightforward guy. Here's the link:

http://www.bladeforums.com/forums/showthread.php?t=480424

WARNING: Like many BF threads on controversial topics, this one has a lot of superficial, uninformed crap from other members who have posted to it. However, if you just scroll through and read Phil Wilson's posts, you will get a very nice education on these knives and how they measure up.

will

[shmoopiebear]

... although there is that reference to one's heiney....

"But" what of the rest of the knife? The focus is on the edge being superior. The foundation of the strength of the knife lies in the integrity of the rest of the blade to hold up, too.

Why was a certain knife shape/design chosen and just who did they consult for that? How is the rest of the blade structure compared to other blades out there? What knives did they compare it to? What happens if the edge gets damaged or it's corrosion resistance? How can it be repaired or sharpened?

Other than the above I would be curious if some of the conventional care and maintenance questions were to be applied to the knife what the answers would be. Since it is new tech I imagine the price on the knives would not be cheap. Some testimonials would be useful to help assess the performance of the knives.

[shmoopiebear]

Thanks, Will. Food for thought. It sounds like the knife is a keeper for life even though it is still cost prohibitive. I am still curious how it can be maintained over time especially if the edge degrades or is damaged for whatever reason. New tech presents new issues. I'll stick with the conventional knives and what I know of them for now.

[will york]

I don't see that it's that big a deal, really. Phil says it's not any more difficult to sharpen than other high wear-resistant steels like S90V, and I have yet to see any steel that can't be sharpened with diamond hones. It's expensive for a production blade, but no more so than many customs on the market. I think it's one of those niche-market things that will appeal to some, but all told it doesn't look any more appealing to me than a lot of what's out there already.

For example, I like the properties of S90V better in the head-to-head testing done by Phil. The fact that a friction-forged edge is rust-resistant does make edge degradation less of an issue when the knife is stored over time, but with the rest of the blade being non-stainless I think it's less appealing than an all-stainless blade like S90V. And I thought it was interesting in Phil's edge testing that although the friction-forged D2 did well in the long run, S90V actually cut longer at lighter pressure (under 25 lbs) than the friction-forged blade. And I rarely let a blade get to that level of dullness before I re-sharpen anyway.

To me, it's a case of someone making an interesting discovery, deciding to hype it up as a marketing strategy, and in reality is offering a little improvement in some limited areas of performance as a novelty--but you definitely pay for that novelty. All in all, if it rings your bell buy it. I don't plan to.

[me2]

I had a discussion, in a separate thread, with the researchers who pioneered the friction stir processing technology a while back, after the BF thread. The initial use of the friction stir processing that I'm aware of was welding, and it could give aircraft quality welds between normally incompatible metals, such as aluminum and steel, which was the article I read. There are many things that I think people do to prove it can be done, then have to find a use for it. Time will tell, as the tech is fairly new, but it will find more and more uses and become cheaper the longer its out there.

The properties of the D2 were quite interesting. I cant reference it, but I heard on BF that the rest of the blade is spring tempered D2, low 50's HRc hardness. The stir processing heats the D2 to the point that enough of the chromium is disolved for the stirred region to become stainless. Most D2 has enough Cr to be stainless, but its tied up in carbides for wear resistance, so it doesnt work for corrosion resistance. The stirring process free's up the Cr and carbon, allowing the exceptionally high hardness. Carbon tied up in carbides doesnt contribute to hardness when quenched. As I understand it, the stirred portion is left as stirred, without further heat treatment, and the blade ground to shape. Since D2 is air hardening, air cooling from the stirring temperature will harden the edge. This leads to some interesting lines of reasoning. Since conventional D2 gets its wear resistance from chromium carbide, and since nearly all the chromium carbides are disolved, the edge retention depends almost solely on the very high hardness. Last I checked, the researchers were still quantifying the volume percent of carbides in the stirred structure. Normally, a high carbon steel is very brittle at these hardnesses, 66-68 HRc were the numbers I heard floated around. The trick of the friction stir treatment, and one reason it works on the dissimilar metal welding, is that it breaks up any coarse structure that forms, and after the spinning mandrel passes, there is not enough heat for long enough to allow the coarse structure to reform. Basically, it has a super fine grain structure that compensates for its high hardness. The grain size is about 4 times smaller than the finest grain structure of 14 that Ed Fowler gets for his low temperature forged blades. 15 is as low as the scale goes that I've seen, taken from Verhoevens heat treating text. Size 14 is about 2 microns, and the diamond blades claim a grain size of 0.5 microns. The scale is an ASTM standard and the size numbers work like sheet metal gauge numbers, ie, larger numbers mean smaller sizes. I havent heard much more and the flap seems to have died down after the great BF thread, but its very interesting. It seems to me that any steel than could be plate quenched could be used. Someone tried plate quenching some thin O1 and had good results, so maybe we'll see some friction forged O1 and A2 as well. O1 is already very fine grained, so I wonder how much lower the limit is, since the sizes obtained from Friction Forging are smaller than anything I've heard of before.

And yes, I'd like one big enough for Noss to do some chopping and batoning tests.

[shmoopiebear]

I remember an article I read somewhere about cars that were riveted the conventional way in comparison to how some cars now use glue. Apparently the new cars with glued bodies take vibration and stress better in some ways of driving than the riveted cars. I could follow the logic of that article relative to old versus new tech.

When I see the friction forging I don't get the same kind of feel for it as the previous logic. On another tangent I have seen how they have come out with now cheaper dendritic knives. I do not know if they are very good although I know that dendritic knives used to be quite expensive to make.

Like the dendritic knives I feel the friction forging will get cheaper as the technology matures and gets cheaper. It's still a novelty to me and I do not think friction forging is better than any other knife. The feeling I get about them is the same when dendritic knives first came out. Check out the prices on the Dendritic Condor line for example. People even make dendritic customs and they have their fans. Perhaps friction forging will go the same way.

[kurodrago]

I would like a knife made from Nanotechnologyand a Scientific test on it:p:D

[will york]

Basically, it has a super fine grain structure that compensates for its high hardness. The grain size is about 4 times smaller than the finest grain structure of 14 that Ed Fowler gets for his low temperature forged blades. 15 is as low as the scale goes that I've seen, taken from Verhoevens heat treating text. Size 14 is about 2 microns, and the diamond blades claim a grain size of 0.5 microns.

That was a nice rundown, me2--thank you. As for the fine grain structure, 0.5 micron is very fine but not unheard of in conventional forged blades.

In the October 1997 issue of BLADE Magazine, Ed Fowler reported on a 52100 blade tested by Metallographic Laboratory Services in California. The owner of the lab stated that the sample had the finest grain structure in the cutting edge of any steel he had ever examined, with carbide size between 1/2 and 1 micron. I contacted Mr. Fowler in 1999 about that test blade, and he told me it had been forged and heat treated by Master Smith Rick Dunkerley of Montana. Rick later confirmed for me that the carbide size actually ran smaller than the lab's testing technology could accurately measure and was estimated by another tester using different technology to be closer to the .5 micron size.

I think your last comment concerning a blade Noss could destruction test is a good one. Once you wear the edge back beyond the area that has been "stirred", it seems you'd be done. I've seen estimates that this area may extend back as far as 1/3 inch or so from the edge, but if there were edge segments in which the treated area weren't as deep, or if the heat stir process has a progressively lesser effect as you get back from the edge, you might find yourself with a shorter lifespan for the blade rather than a longer one. I've wondered if that may be why the knives being offered are of the smaller hunter/utility variety, rather than a blade meant for harder use where edge rolls/dents/damage can be common.

Interesting comment by shmoopiebear about the dendritic stuff, also, which goes in the other direction in terms of grain-size. I don't know about all processes currently producing what are called "dendritic" blades, but the technique used by David Boye of Arizona (who I believe coined the term) is actually a casting process with no forging involved. This is what leaves extensive "veins" of large "carbide crystal" grain structure running through the steel and is purported to have a micro-serration effect as the softer matrix is worn away in use and these large jagged chains of carbides are exposed at the edge.

[Noss]

I was wondering if you have heard of this maker. Any chance of one being tested.
http://www.diamondbladeknives.com/frictionForging.aspx


I may test one at a later date. I getting read to take a needed break from testing.

[me2]

I dont want to sound like a knowitall, but I probably will anyway. Just read the latest thread by Kevin Cashen on BF and the extra info from Mete and you will know how much I dont know. Ok, here goes. The carbides in the Dunkerly blade are very fine, but no dimension is given in the article for grain size. Most, if not all, of the article is reprinted in Fowler's first book. If a measurement of grain size is given in the article, then I missed it or it didnt make it to the book. Absent a measurement, I only know of Ed's ASTM size of 14 that he's mentioned in some BF threads. IMS, Verhoeven also references some carbide sizes smaller than 0.5 microns in his bladesmithing and heat treating book.

Kurodrago, steel uses nanotechnology:D Carbides can be 10's of nanometers, and the ones in the blade discussed above are 500 nanometers. Some hand sharpening procedures can yield edges with flats less than 300 nanometers wide. Scalpels are considered passable at widths of 1000 nanometers. I must admit that a diamond edge reinforced with carbon nanotubes does have some appeal though. Its the 3-dimensional weaving of the pesky tubes that is the issue.:D

[shmoopiebear]

Interesting comment by shmoopiebear about the dendritic stuff, also, which goes in the other direction in terms of grain-size. I don't know about all processes currently producing what are called "dendritic" blades, but the technique used by David Boye of Arizona (who I believe coined the term) is actually a casting process with no forging involved. This is what leaves extensive "veins" of large "carbide crystal" grain structure running through the steel and is purported to have a micro-serration effect as the softer matrix is worn away in use and these large jagged chains of carbides are exposed at the edge.

Which gets back to the original point of what knives are for and what they should be good at which is... cutting. You look at the Cold Steel line where they make lines with both plain edge and serrated as a choice. I have read about how some people say that the serrations are an unfair comparison to a plain edge blade for cutting performance. I personally don't it's an unfair comparison so as long as the knife gets the job done and done well. Again, performance.

As for the ability to do maintenance and upkeep easily, longevity of use, types of cutting and materials involved, etc... that all depends on what kind of knife design one wants to do on what type of job. A boning knife is not a chopper and vice versa although there are knives that fit the bill for both. Between the dendritic and the friction forged knives it really doesn't matter how they are made as long as they do the job well and are proven. The rest of the issues I will leave for the knife philosophers and technicians.

[will york]

The carbides in the Dunkerly blade are very fine, but no dimension is given in the article for grain size. Most, if not all, of the article is reprinted in Fowler's first book. If a measurement of grain size is given in the article, then I missed it or it didnt make it to the book. Absent a measurement, I only know of Ed's ASTM size of 14 that he's mentioned in some BF threads.

The reason I had the exact name of the lab was that I took that information down directly from the article as it appeared in Blade in 1997. The remarkably small grain size as described in that article was one of the reasons I contacted Fowler, and then he directed me to Dunkerley. If I had thought that anyone would question my veracity in taking down the information, I suppose I could have photocopied the article at the time--never occurred to me that I would need to defend myself in that way. I have no reason to make up a figure like that.


Since I don't have the article, I suppose it's possible that when I entred that quote in my computer file of knife notes, I may have interjected information I got directly from Rick Dunkerley about the grain size as measured. I don't think that's what happened, but since I don't have the article to prove it and you say the article as reprinted in Fowler's book doesn't contain the measurement, I suppose that is a possibility. But I can assure you that I didn't offer that figure "absent a measurement" as you put it.

[me2]

Ah crap. Will, I didnt mean the post to sound that way. Your numbers are correct. The carbide size is given in the article, but the grain size is not quantified, just stated as the finest the lab manager/owner had ever seen. I was not questioning your veracity, just doing a bad job of making a point about the difference between carbide and grain size. Sorry for any offense and misunderstanding.

Back to Friction Forged D2, an ASTM grain size of 15 has an average grain diameter of 2 microns. This is considered ultrafine, and is attained with special treatments to minimize grain size. The FFD2 is 1/4 this. D2 is known for a fairly coarse carbide size, 30 times or more larger than the ones found in Ed and Ricks 52100 blades. No mention of carbide size has been made for FFD2, and it sounds like they could be even smaller than those in 52100, if any are present at all. Basically, FFD2 uses a grain size that is beyond "ultrafine" and a minimum amount of carbides to make untempered, high carbon martensite tough enough for general small knife tasks. The blade performance doesnt sound like anything beyond what can be acheived using other processes. However, the technique to get there is quite amazing. Has anyone taken a FF blade down to less than 10 degrees inclusive to check on edgeholding that way?

[will york]

Apology accepted.

Edited to say I think we were both victims of web-itis. The distinction between which grain structures were being discussed I'm sure would have been clear if both of us had taken a little more time in the writing and reading of the posts, but these days a short scribble gets out into cyberspace a little too quick sometimes.

I see now that you were talking about grain size across the whole martensitic matrix, where I was talking about the grain size of the carbides contained in the matrix. Sorry I jumped--I should have known I was missing something in your post as I know you are not that sort. Your apology was generous, and I can now see how I was at fault in misconstruing your words.

I apologize, also.

[dingyu1980]

what a Promising steel!!!! sonds good !!1
but i do not belive in what the pagesite have said!!!!
just a boast

[me2]

OK, ktc (knifetests.com) ate my post. Anyway, what I tried to say is apology accepted, though I still think I was being a knowitall.

I was rethinking the large blade applications of this process. Does anyone think the spring tempered spine would make it useful for 7" blades or larger, or would the edge get mangled to the point of uselessness? I thought the ABS guys that reviewed them did some bend testing and found it to be acceptable.

Dingyu1980, what part is a boast? It doesnt really matter to me. I wont be getting one until the process is so common that the RADA Cutlery knives for $7 are using it. Speaking of which, I need to go turn a RADA Santoku into a clip point untility. Later.

[will york]

I was rethinking the large blade applications of this process. Does anyone think the spring tempered spine would make it useful for 7" blades or larger, or would the edge get mangled to the point of uselessness? I thought the ABS guys that reviewed them did some bend testing and found it to be acceptable.


Might make a nicer package with a steel more suitable for spring tempering than D2, but obvioiusly a quick D-test by the Nossmeister would give us the short answer. Spring tempering D2 reminds me of something once said about Ed Fowler's incredibly involved, complex and seemingly mystical heat treat of 52100, which is: "When all is said and done, it's still 52100."

[me2]

Spring tempering D2 reminds me of something once said about Ed Fowler's incredibly involved, complex and seemingly mystical heat treat of 52100, which is: "When all is said and done, it's still 52100."

I'm glad I'm not the only one to think that. I was reviewing his first book when the above discussion about grain and carbide size came through. You cant argue with results I guess, but it seems there should be a point where one asks "Ok, I've got a long recipe here, but I'm not totally sure what elements are required and what parts are not. Lets try to simplify things and see whats really necessary."

I'm assuming a high hardenability is needed for the friction stir process to work for knives. How about A2, A8, S7, and some others along those lines. 440C and the Sandvik stainlesses come to mind. I prefer tool steels, but there's no reason stainless couldnt benefit from the process. The guys at BYU said they were working on other steels, but I havent heard any results.

[will york]

S7 sounds like a great foundation, with its toughness. M2 also might offer possibilities?

[me2]

I hadnt thought of M2. If it works for D2, it should work for M2. M2 (and the Molybdenum based tool steels in general) have tighter tolerances for temperatures during heat treatment, and the carbides are difficult to disolve. This would make M2 trickier, but not impossible. D2's carbides disolve easier, but there are a lot of them. The temperatures are pretty narrow there as well, but overall lower than M2. While we're generally on the topic of hard edge, softer spine blades, how is it that saws-all blades are about $5 each with a hard edge and soft spine, but in knives its some sort of super expensive process that only a few know how to do right? I say bring on the 4140, or whatever bi-metal saw blades use for the spines, and M4, or whatever edge wire is, and make 1/16 to 1/8 inch spined knives that are nearly indestructable, but hold an edge like a bi-metal hacksaw blade on aluminum. I know saws-all and bi-metal blades are straight, but it cant be that hard. Start with sheepsfoot and wharncliffe blades if its that big an issue. I'd buy the sheepsfoot and wharncliffe bi-metal blades all year long.

[will york]

That makes way too much sense.

You'd be better off starting with something made of unobtainium that weighs four pounds plus and costs $800. Then you could readily compete in the high-performance market--whether the knife actually performs or not. I think CRK's fatal flaw was pricing its knives too cheap--if it had marketed them @ $1,000 a throw, Noss probably wouldn't have sprung for one and tested it in the first place, all the rest of them would remain safe queens, and everyone could rave about how no other knife could touch them for performance.

[me2]

Your insight into the reality of price vs performance is staggering. Seriously, when a $300 knife is outdone by a $30 one, there are serious issues. I try to keep in mind that this was just a toughness test, and the GB and Project 1 might blow the GI Tanto out of the water in cutting ability, edge holding, and sharpenability (Ed Fowlers criteria for knife performance). Then I think if it breaks, what does all that matter? Hell, I'd bet the GI Tanto holds an edge longer during chopping and batoning, just because the edge on the GIT isnt fracturing. Anyone know the hardness of the GI Tanto, or the other knives of that series? I'm guessing 50 HRc or so. I watched a YouTube vid of the CS machetes made in South Africa testing out to 48-49, and mine held a pretty good edge while chopping through 1.5" oak dowels. I'm sort of at odds with myself. I love the high hardness steels like Diamond Blade D2, mechanical hacksaw M2, Alvin Johnson 1095 and O1, but also have a place for spring tempered 1055 and moderate hardness S7. I havent actually used most of these, but its good someone tried it and made it work, then had the materials science explanation to go with it, in Alvins and BYU's case.

[will york]

In the absence of hard testing such as what Noss does here, I wonder if edge holding just got too much play over too long a period, resulting in the high-end market going toward higher and higher hardness to get more and more wear resistance. When in reality, a hardness range in the 50's Rc complemented by truly high toughness might make for a better performance balance.

I've knocked chunks out of the edges of expensive blades by pounding them through bones in the past. Conventional wisdom would say just don't DO that, but I've used a steel hammer to pound a $20 Ontario machete long-wise through the skulls of countless deer to remove the face plate with antlers. As for performance, here's a pic of that machete taken after a fresh sharpening. You can see the bright undulations along the spine caused by hundreds of hammer impacts over the years.

[me2]

Where's the effing cameraman and his pigtail casserole story? I remember that big nasty edges thread on BF. Very entertaining and informative. An Alvin special paired with a good tough tool like that would be the best of both worlds. I get really tired of the right tool for the right job arguement. It comes up whenever anyone does anything that damages a knife over on BF. The last one I posted to was about cutting copper electrical wire. If a $70 knife cant cut speaker wire, it has issues. Technique has a lot to do with it though. Sawing on copper wire with a plain edge wont get you anywhere but back to the sharpening stone, and using serrations will probably cut it, but mangle the serrations. Its soft copper, just lay it on a block of wood, put the edge on it and press. You cant cut hard materials by sawing on them with a plain edge blade, and since serrations cut so well in part because of the thinner inclusive angle, they'll get mangled. The whole reason for moving to metals in the first place was because stone tools lacked the durability we wanted. It may just be cutlery rumor, but obsidian is widely reputed to take and hold a finer cutting edge for soft material than any steel. If you drop it, however, its gone. What good is that edge and edge holding if its broken? Right now, I lean toward the all or nothing school. If its sold as tough, it better take at least a 4 sword beating to break it. If you take toughness out, it had better be as hard as it can be, but still be tough enough that if I drop it making dinner, I'm not looking for where the broken piece went. I dont expect I'll ever hammer on my M2 puukko, but if I have to, it will hold up better than most people think.

[will york]

I had an archaeologist neighbor who, along with some cohorts, learned to flint-knap obsidian blades and used them to shave with. He said the edge would begin to deteriorate immediately after knapping if left exposed to the air, so they kept their shaving blades in a glass of water next to the bathroom mirror.

To go a little further off-topic, he also shared an interesting (to me) classification system used by archaeologists to denote how advanced pre-homo-sapiens cultures were, based on how much linear edge they were able to knap from a pound of obsidian. Neanderthal man got about 12 inches and Cro-Magnon about 12 feet--an order of magnitude.

[Noss]

I think CRK's fatal flaw was pricing its knives too cheap--if it had marketed them @ $1,000 a throw, Noss probably wouldn't have sprung for one and tested it in the first place, all the rest of them would remain safe queens, and everyone could rave about how no other knife could touch them for performance.


Yeah If it would have cost this much It would have been safe from me. :D Unless someone donated one and there was not much chance of this happening if they went for 1 grand.

[Noss]

Damn that machete is a freaking razor Will. That's a dramatic photo. I agree knives should have a balance between toughness and edge holding. On tough hard use knives and knives sold under these words then they should be tough first in my opinion. To make a big hard use work blade chopper out of some fad fragile steel does not make sense to me. I have many softer knives in the lower 50's that work just fine for cutting without always having to resharpen them. True many don't hit their blades with a hammer but for me also I don't or have I ever cut 10,000 pieces of rope in a single time either so it kind of goes from one extreme to another. I have hit a user with a hammer before to cut through hard materials like heavy wire. ( I don't mean while testing) so toughness is more important for the way I use my knives. If your machete broke when you hit it with your hammer it sure would be of no use to you anymore but it held up to the task and lived to work another day. :thumb:

[Noss]

me2: I working on expanding edge retention testing here at KT in a big way. I curious to move into other testing areas as well. If everything goes well then then we should see some very in depth edge retention comparisons. All of this is still in the works so I'll have more details about this later. I just don't want to work myself into a hole at the moment. I've been there before already.

[will york]

... working on expanding edge retention testing here at KT in a big way...curious to move into other testing areas as well. If everything goes well then we should see some very in depth edge retention comparisons...

Let's continue--on all fronts! Good news, Noss.

[mljoshua]

Personally, I can't believe how technology has advanced in knives - never considered the friction issue until I read this post. I admit though, I mostly buy the knives because I like how they look, so function has not been as important to me. I like to display them, more than use them. (Hope that doesn't get me booted from the discussions)

[TwoBrothersBrickPaving]

I have heard of them, however, I have yet to test one.