Anyone ever worked with D3?

qwertyname · Jul 26, 2001

Perhaps this is in the wrong setting, but I happened to be out looking for different knife steels, and I happened on to a tool steel called D3, Chemical makeup: Carbon: 2 - 2.35%, Silicon: 0.25 - 0.45%, Manganese: 0.24 - 0.45%, Chromium: 11 - 13%, Vanadium, Molybdenum, Tungsten: 0.8% (Taken from a number of websites)

Now I compared that with one of the current "supersteels" CPM440V:
Carbon: 2.15%, Manganese: .40%, Chromium: 17%, Vanadium 5.5% and Molybdenum: .40% (Taken from Admiral Steel Website)

Major differences between the two are the increased Vanadium and Chromium in the 440V both of which make it harder to grind/machine if I am not mistaken. (Obviously, the range of D3 isn't as specific as the 440V, but the 440V alloy fits within the range of percentages listed under D3)

After reading a bit further on the D3 about heat treating and performance, it seemed that it had excellent properties when hardened between RC58 - 60 particularly if cryogenically treated.

Now, all of this I have found is only on paper - I'm not a heat treater, and only had a few metallurgy classes in my engineering coursework, but off hand it looks like it could be an excellent performing steel, that is much easier to work than 440V while giving up the stainless characteristic. So, has anyone ever worked with it? Or have a knife made out of it that can say something to its performance? I have designed a couple of pretty simple small fixed blade knives that I am considering getting made up in some different "supersteels" so that I could actually have an "apples to apples" comparison of them. (It is a longer term project, so don't hold your breath on results, although I would certainly post them on the forums somewhere.)

Cliff Stamp · Jul 26, 2001

D3 has about a 5-7% increase in wear over D2 and a 25% loss in impact toughness (charpy v-notch). You are better off looking at M2 or a CPM steel, for example 10V.

-Cliff

Danbo · Jul 26, 2001

Cliff, how about D7? Analysis wise, it looks really good. Seems to be D2 on steroids. Done any testing on this stuff?

Cliff Stamp · Jul 26, 2001

I have done no work with it and doubt that I will as I have never seen them (D3,D5,D6,D7) recommended strongly. If a maker was confident that he could produce a superior blade out of say D7 as compared to M2 / 10V etc., then I would be of course interested, but as of yet I have never seen anyone promoting such steels, which agrees with the materials information I have read.

-Cliff

Alberta Ed · Jul 26, 2001

Ivan Campos of Tatui, Sao Paulo, Brazil, works in D-3 (or K-100, which he says is the same thing). Do a search under the Custom Knives forum and you'll find his posts (his website is currently down, though.) I have his Standard Tanto in this steel, and it takes and holds an awesome edge -- chisel ground. I did a review on it here last January or February. My tests included slicing cardboard, whittling down a 2 x 4, cutting nylon rope. Oh, and it works great for chopping veggies and slicing pepperoni (I'm right handed and the chisel grind is on the right). I'm not sure exactly what Cliff Stamp's technical analysis means (I wouldn't dispute him, though), but this knife gives me the feeling I could pry up manhole covers with it, no problem. And then use it to shave.

qwertyname · Jul 27, 2001

Cliff,

I would be quite interested in the references you have which give you that information. I have been looking about the internet for some and have been coming up a bit short.

I am interested further for a couple of reasons. In general, you can significantly influence the impact performance of a steel in the Charpy test via the heat treatment. The Charpy V notch test (and all such tests) are highly related to the modulus of rupture which is extremely dependant on the grain structure of the steel.

To take this a step further, one of the primary complaints about CPM440V in the early stages was that at the higher hardnesses, which people thought to be reasonable for the carbon content, it had significant problems with impact toughness, and overall brittleness. However, with experimentation, it appears to have become a much better all around performing steel when heat treated to a lower hardness.

I'm not necessarily sold on the idea that because makers aren't using D3 it isn't possibly a superior material in some conditions. After all, there are a wide variety of steels available, and it takes time for them to diffuse into the market. Certainly it took a long time for ATS34 and 154CM to become widely accepted, and that process is only now starting with M2, BG42, 440V, 420V and the like. Incidently, even looking at M2, there are a number of companies that now manufacture something called M4 which, as a tool steel, is perported to outperform M2 in virtually every catagory. (M4: C:1.45, Mn: 0.25, Si: 0.25, Cr: 4.5, V: 3.85, Mo: 4.5, W: 5.5) Certainly, looking at its alloying elements the potential seems there to be an excellent knife steel, but I haven't heard of anyone using that either.

I am not trying to insist that D3 is a great knife steel - please don't interpret this as that. I am simply interested in seeing where some of the information presented has come from as the history of knifemaking is frought with steels that were discarded and then found again under different conditions.

Cliff Stamp · Jul 27, 2001

qwertyname :

I would be quite interested in the references you have which give you that information.

"Heat treatment, Selection and Application of Tool Steels", by Bill Bryson, Crucibles reference material, a couple of Materials texts, and come conversations with a few knifemakers.

In general, you can significantly influence the impact performance of a steel in the Charpy test via the heat treatment.

Yes, but its not trivial, steels tend to operate best (from a combination of properties point of view) at specific RC values.

[440V]

it appears to have become a much better all around performing steel when heat treated to a lower hardness.

Not from what I have read. I have seen multiple reports of low performance as compared to ATS-34 because of excessive edge indentation and rolling. I think 440V is a good steel, but not for the type of knives that Spyderco is using it on, and this illustrates the problem with the "just make it softer" approach.

To get specific, the charpy c-notch value for A2 is 41 ft.lbs at 60 RC, tempered at 500 F. As you increase the tempering temperature so as to soften the steel you actually decrease the c-notch toughness down to 29 ft.lbs at a 900F temper, 58 RC. However contrast that to A6 which when tempered at 300 F to produce 60 Rc, has a c-notch charpy value of 27 ft.lbs, *and* this steadily <b>increases</b> in a linear fashion as you raise the tempering temperature.

So A2 has the benefit of greater edge holding for light use work because of the higher hardness and wear resistance, but for really heavy work A6 would be a much better choice because of the extra toughness, and to get A2 at the same toughness you would need a much lower RC and thus see poor resistance to edge rolling and impaction.

even looking at M2, there are a number of companies that now manufacture something called M4 which, as a tool steel, is perported to outperform M2 in virtually every catagory.

Yes, except that it takes a 30% loss in impact toughness and has a lower machanibility. I would be interested in M2 or M42 at 66-68 RC. The resistance to edge deformation and wear resistance would be very high as say compared to D2 at 60 RC. The problem would be the ductility at that very high RC. How hard would it be to break a piece out of the edge?

I am not trying to insist that D3 is a great knife steel

I don't doubt that it wouldn't be. All steels will make great knives if the blades are ground so as to suit the abilities of the steel. My point is simply that for the kinds of things you are probably looking for in D3/7 over D2 (wear resistance, higher RC) , you are probably better off looking at M2 or the CPM steels, as you can get the same advantages as well as a greater toughness and thus probably run the RC a little higher.

-Cliff

qwertyname · Jul 30, 2001

Cliff,

I'll definately have to find the reference you mentioned, I appreciate it. From what I have read to date, at least anecdotally, different companies do seem to get a fairly wide range of performance out of the same steels, and I'm not really sure why. Taking your
example, while Spyderco may have some problems with 440V, off hand I don't remember complaints regarding Kershaw's use of it in the Random Task series. In addition, it does seem that certain of these steels are much more sensitive to certain treatments than others, such as
cryogenic quenching.

As it turns out, the designs I have been considering one of the really higher carbon steels for is something like the Subsniper you just reviewed. A knife where I am not particularly concerned about the impact toughness, more so the wear resistance and fineness of grain. Much as you indicated in your review, in the smaller knife a hard thin edge becomes optimum, and a balance of edge holding vs. ductility becomes the issue. Incidently, have you considered having such a knife made out of even more extreme materials? In one direction, you could go with a ceramic or tungsten carbide alloy for really extreme hardness. Certainly at really thin geometries the ceramic would chip out too easily, but I'm not as sure of such with a tungsten carbide alloy. Or, more as I was thinking in my application, get something that is a bit less hard, but still has excellent wear resistance, potentially to limit the chipping at the really extreme edge geometries you mentioned in the review. Since you seemed to have a put a fair amount of thought into the Mel Sorg knife, as well done some study on the SubSniper I'd be interested in reading your thoughts.

rdangerer · Jul 30, 2001

Originally posted by Cliff Stamp
... Crucibles reference material, a couple of Materials texts, and come conversations with a few knifemakers.
-Cliff

Cliff, if you would be so kind, would like to know which Materials texts you think are worthwhile, and which specific info from Crucible should I seek out... PDF's on the web?

I do have the Crucible Tool Steel & Specialty Alloy Selector handbook. Pretty good... but... often unlabeled comparison graphs, and not the sort of detailed curves on say tempering temp vs. HRC vs. Toughness that I'd really like to see.

Cliff Stamp · Jul 30, 2001

qwertyname :

different companies do seem to get a fairly wide range of performance out of the same steels, and I'm not really sure why

While there are factors that can effect the material properties of the steel (who made it, the heat treat specifics etc.), I would assume what you are seeing is mainly do to the fact that the geometries are different. The reason that most people think ATS-34 is hard to sharpen for example is that many popular companies using it sharpen their knives at really obtuse angles and thus when they go dull, and people try to sharpen them on something like a Sharpmaker they can spend 15 minutes of constand grinding and see no results as all they are doing is hitting the shoulders. As well the natural angle that I have seen most people use freehand is much lower than is commonly factory ground. In contrast see the graph in the MEUK review that shows the Sub-Sniper sharpening at twice the speed of the 52100-MEUK - why, the geometry allows a much greater rate of metal removal, well in excess of the easier machinability of 52100 vs ATS-34.

In addition, it does seem that certain of these steels are much more sensitive to certain treatments than others, such as
cryogenic quenching.

Yes, check out for example :

http://www.effingham.net/mei/cryoProcess.html

However keep in mind that much of the information regarding deep cryo is being researched by people selling deep cryo equipment. If you ask the people who are on the opposing point of view (multiple tempers), they will say their method can produce the same results - the cryo people don't agree. I think later the fall I will get two unmarked blades made out of the same steel, D2 seems an obvious choice, and see if I can tell the difference between the one with the deep cryo and the one with multiple tempers.

have you considered having such a knife made out of even more extreme materials?

Yes, I have been thinking of CPM REX 121 (HS), as an extreme upper example and get it heat treated to 69-71 RC. I have discussed this with a couple of knife makers, for example :

http://www.pbknife.com/

Who has worked with very high performance alloys (T15), and he was very wary of ultra-hard alloys like M42 (66-68 RC), because of the very low ducility, which as you noted is more important than the impact toughness - which is not that low.

Lately though I have been turned around in my thinking because of work I have been doing with the 52100-MEUK. While it doesn't have the edge holding abilities of something like CPM-10V (in a totally different class), it does have a very durable edge. I have been using this very fined profiled knife to do a lot of things I would not have thought possible. After using it in the kitchen extensively and seeing it easily be able to take cuts around bones and including through poultry bones. I was curious to see if I could do something like scale like build a full size shelter with it - without using deadfall as buliding materials.

The first thing I did was carve a club out of a piece of 4" deadfall. Cutting off a length of the tree was difficult as the knife is too small to chop, so I had to just slice out a notch. The point is also to fine to do any kind of forceful prying so I could not stab into the tree and work the hole to weaken it. After a few minutes though I was about 1/3 of the way through and then I just reversed the tree, placed it over a rock and jumped on it to break it in half. I then cut the bark off, and then scraped the club clean. This was pretty hard on the blade as there were a number of knots and I wanted to see if I could do it without being too careful about the knot impacts. It handled it fine. I then used the blade to remove the knots, which required some forceful cutting into brittle material, which is always bad, and then carve the handle. The blade came through with no problems.

For a very specific use blade I think the high performance alloys like 10V have their place, but for a general use knife, I think that there is certainly value in the simpler alloys as they are more durable and thus offer a wider range of tasks. Then again I might have a skewed idea of the performance because I never pushed as hard on the other thin blades I had as the MEUK was an experiement. I might repeat some of the work with the 10V blade after discussing it with Phil Wilson, I will certainly try it with the D2 one. I might also just be seeing the benefits of a full convex profile.

Rdangrer, I never referenced most of that material as I had just assumed it was for personal use, I do intend to clean up some of the references when I get some time as there is a lot of conflict, for example the cryo perspective mentioned above.

-Cliff

Joe Talmadge · Jul 30, 2001

When I see carbon content that high in an ingot steel, I tend to look elsewhere. CPM gets away with it, but they get away with a lot of things due to their manufacturing process. I'm not surprised at all that Cliff thinks D3 won't be tough, I would have predicted that just based on the C content alone.