Diamond Blade Knives

MikeC

MikeC

Joined
Sep 16, 2005
Messages
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I've just finished reading several articles about the new diamond friction forging process and the new diamond blade knives. They claim the edge zone and tip are rockwell 65-68. Won't this be a problem with edge chipping or chip out and tip breakage if the knife is not handled and used very carefully? Someone please help me to understand how the edge zone and tip is not going to be brittle? The knives may cut forever, but are they going to be tough? Just a couple of my questions? Anyone know anything about this process are these knives??

Thanks in advance
 
This is already an issue with ceramic knives, which are extremely hard. The edge lasts for a long time, they can get very sharp, but are hard to sharpen and if treated bad can break. Ceramic blades are mainly used in kitchen knives, where abuse isn't likely.
 
I'm constantly reminded of that old dictum: "Your knife is the most expensive and least effective prybar that you will ever own."

I am constantly amazed that people use their folding knives for so many things other than cutting. I can understand with big fixed survival knives, but with a small knife?

I would think having a very hard sharp cutting surface even though it's brittle would be a very good thing as long as you slice, push cut and so on rather than abusing. A good friend of mine has had a ceramic chef's knife for several years and used it relentlessly with no problems whatsoever. We're talking up to 8 hours a day in a restaurant kitchen. Periodically he sends it back to the manufacturer for sharpening. End of story.
 
prying doesn't chip your edge, contact with the wrong materials when cutting can chip your edge. It can be a very real concern for an edc, depending on what you do.

I don't know about the FF blades, I think I've only seen a couple members mention having one.
 
Yet they have a spine hardness of 45 or so. It is apparently a very flexible steel.
 
I'd have to disagree with the assertion that kitchen knives are not likely to be abused. Perhaps a ceramic kitchen knife isnt likely to be, but the rest sure are, IME.

I dont see any mention of prying by the original poster. Also, the diamond blade brand didnt make a folder, although one was planned and may now be in production. Also, a knife as hard as the HRc numbers mentioned will sometimes make many small knives if dropped, and can chip if any hard material is encountered during cutting, like copper staples, regular staples and sometimes even the cardboard itself, not to mention knots in wood and such.

As to the original question, the process uses a spinning mandrel which is pushed through the metal. Friction heats the metal into the forging range, possibly even the forge welding range, and then stirs the metal. There is a short video of the process and it looks a lot like running a mixer through stiff dough, except for the red heat, and the sparks and such. D2, an air hardening alloy, is used as the base metal, and after the pass through the metal, it air cools and hardens to the listed hardness. No tempering is done afterward. The spine is left soft because the mandrel only stirs about a 3/8" wide section. The mass of the rest of the piece also pulls heat away, aiding in the "quenching" after stirring. The reason that the edge and tip are not unusually brittle is the process produces a very fine grain size, which aids in toughness. The grain size is about 1/4 the size of the smallest grains listed on the ASTM grain size chart I found in an online metallurgy text. Standard ultrafine grains go down to about 2 microns IMS, and the friction forged grains are supposed to be about 0.5 microns. Also, the stirring process puts enough chromium from the D2 into solution for the edge to be stainless. D2 has just barely enough chromium to be stainless, but so much carbon that most of the chromium is tied up in chromium carbides, which gives D2 its amazing wear resistance when hardened normally. This process dissolves the chromium carbides due to the temperature used and allows all that extra carbon to contribute to the very high hardness and all the chromium to aid in corrosion resistance. All in all, I find it a fascinating process, although the knives are a bit pricey for me. Other metals were being tried besides D2, and the researchers who developed the process have also used the stirring process to weld aluminum and steel without the brittleness usually associated with welding the 2 together. Of course, steel can be welded to steel as well. The original developers also post here, and I'm sure they will post to clear up any inaccuracy in my summary. They were still working to quantify the amount of carbides dissolved and a few other things last I heard.
 
I have the dubious honor of having one of the first FFD2 Goddard's that were made available to the public. I was all excited about it, and posted a thread about how great they are. Well, needless to say, that thread got mashed in the mud pretty quick.
Anyways, I make my own knives now, but, I just can't make anything that compares to that FFD2.
They are unbelievably awesome.:thumbup: (I still don't believe how that thing could hold such an edge.)
 
mmmotorcycle said:
Yet they have a spine hardness of 45 or so. It is apparently a very flexible steel.
Click to expand...
oh man, don't let the guys on the knifemaker forum see that :), they have another thread going about how hardness has nothing to do with flexibility. It is a good read, low Rc steel will bend (not flex) before harder steel, but they flex the same under a load that does not cause the softer steel to deform plastically.

I did see the magazine article with the test blade bent quite far. I like nice and thin knives with good geometry that can do that for certain uses.
 
I'm not talking about using it for a pry bar, hammer, shovel, etc, I'm talking about hitting a bone too hard while cleaning a deer at night, or throwing it into the sink to be washed and bam, the edge chips, or the tip breaks. It just seems like 65-68 rockwell is going to be really hard and maybe to the point of being brittle? I'm not a knife maker, engineer or materials expert. I've heard some reports of CPMS30V being prone to edge chipping or chip out and tip breakage if some blades of this material are used hard due to its high hardness or high RC, so that would lead me to think since the friction forged blades while being D2 steel are greater hardness than S30V, that these blades forged by this method would be subject to the same problems but on a greater scale, I could be wrong about this. That is why I made the post hoping someone could clear this up for me.

Thanks for all the response so far.
 
Thanks Esav, I went back and hit your links and read all of the info, and thanks Me2 and Phil Wilson. Phil you anwsered my question when you specefically stated it should be ok for big game if the user doesn't pry joints or hit bone.

Thanks for the responses and sorry for being lazy Easv and not searching the site before posting. My bad.
 
The only problem I have with FF D-2 is the price tag.
If this steel blew everything else out of the water I'd have some by now, but for the price they ask I could probably get a custom knife made of CPM S125V, which I expect would perform similarly, if not better in some regards.
If I remember correctly CPM S125V reaches Rc65, and is jam packed with vanadium (a double whammy, hardness and wear resistance).

What I'm waiting for is the next steel they use that is better suited to the process. If they get hardness into the 70's with extra wear resistance I'll gladly fork over the cash.
 
MikeC said:
I've just finished reading several articles about the new diamond friction forging process and the new diamond blade knives. They claim the edge zone and tip are rockwell 65-68. Won't this be a problem with edge chipping or chip out and tip breakage if the knife is not handled and used very carefully?
Thanks in advance
Click to expand...

Absolutely. The ceramics chip pretty easily and so do the white and blue carbon steel Japanese blades that are hardened to around RC 63-64. I have personally snapped the tip off a ZDP-189 blade just by slicing. I would view any edge hardened this far as delicate.
 
Knife Outlet said:
Absolutely. The ceramics chip pretty easily and so do the white and blue carbon steel Japanese blades that are hardened to around RC 63-64. I have personally snapped the tip off a ZDP-189 blade just by slicing. I would view any edge hardened this far as delicate.
Click to expand...

The edge is not delicate. The FF process transforms (for lack of a better word) the carbides in the D2 from 5 microns down to 0.5 microns. Granted, I haven't batoned wood with it ($ 400.00 knife), but I purposely let a buddy at work use it to take the backstraps out of several deer with it. I let him do it because the way he removes the backstraps, he digs the tip and belly of the knife into the backbone of the deer with each "stab". No chipping or rolling of the edge; still hair popping sharp after several deer.
 
Mike, the edge hardness is as advertised. About 66 RC. I didn't see any chipping with my testing cutting rope and whittling redwood and Douglas Fir. I was pretty skeptical about the original claims but now believe that it is pretty much everything they say it is. In spite of the softer spine I would not classify this as a blade I would want to pry or chop with. They claimed edge holding was better than S90V. I found it to be in the same class but not a runaway winner. This is so dependent on heat treat, edge geomety, and hardness. Phil
 
Phil Wilson said:
Mike, the edge hardness is as advertised. About 66 RC. I didn't see any chipping with my testing cutting rope and whittling redwood and Douglas Fir. I was pretty skeptical about the original claims but now believe that it is pretty much everything they say it is. In spite of the softer spine I would not classify this as a blade I would want to pry or chop with. They claimed edge holding was better than S90V. I found it to be in the same class but not a runaway winner. This is so dependent on heat treat, edge geomety, and hardness. Phil
Click to expand...

I found it less edge holding then Lauri PT, BG42, CPM S30V and CPM S60V, it may be good . To me it is as good as differentially hardend or tempered carbon steel, no miracle but extreme initial sharpness - hair whittling, and this is what make it looks different for many. From edge holding point of view if you start from same hair whittling sharpness - nothing miraculos. You may see this on my test results.

Also after cutting rope 800 times I found micarta on the handle slightly displaced, which I can feel by my palm and it irritate me - for this price things like this should not happen.

Thanks, Vassili.
 
The Jan 08 Tactical Knives has a great article in it about these. I look forward to the time they come out with some folders in this steel so I can try them.The pricing is high on them I agree.

I've used a lot of the Japanese White and Blue steel blades, tested and used ZDP189 a lot and thought it was great but easily rusted. I deformed a couple blades in that ZDP189 steel and broke the edge and points on plenty of the Japanese blades but didn't chip them or break any in ZDP189. I liked my 13C26 64.5 Rockwell hardness prototype Storm II I tested for Kershaw and it performed well after being thinned down to a better slicing profile but I'd be wary of how much stress I'd put on the edge now compared to what I did to it before that. It held all I dished out before the reprofile though including batoning it through logs and splitting them. It performed well for edge keeping also even with a supposed 25 to 27% retained austenite at that hardness. Go figure.

I'd be very interested in running some of the Diamond blades through the paces to get an idea in my own mind of just how far ahead of ZDP189 and S30V it really is for hemp cutting, carpet remnants cutting, some wood carving in hard and soft woods as well as resharpening to get an idea of that difference too if any and I will own one of the DB offerings if I see it in a folder I like. I've been using a CPMD2 blade in the Tyrade from Kershaw and have been pretty happy with the edge I get and keep with that one but I don't think its any more or less to me than most regular D2 I've used. It does seem to take a higher polished edge better though.

I actually looked hard at the Diamond Blades offered now thinking if one had what I needed that I'd buy it and turn it into a frame locking folder for myself. I just saw nothing that I had to have.

STR
 
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