CruWear vs D2

[Cliff Stamp]

I would like to see a few other steels on that chart for comparison- 3V, Elmax and even XHP.

Here is an honest question, that chart is completely meaningless as there is no information on

-how the steels were hardened
-what exactly was measured
-the precision/accuracy

It isn't even said if the toughness and wear values are on the same hardening cycle of the steel.

There are many ways to measure a property and there are many ways to heat treat steels. Crucible used to be fond of doing something like comparing S90V to 440C and showing the adhesive wear resistance when S90V was hot tempered and 440C was cold tempered without cryogenics. This makes 440C look soft/weak and very low in abrasive wear resistance (as that is what you would think they would be showing but it isn't). It is only when you look at the patent data and see what was done and how the steels were hardened that you realize the data is very misleading.

Anyway, the question is why would that chart make you feel anything or why would you want to see more steels on it. There is no way to interpret it at all and most times, as with all marketing charts, the way data is presented is intentional to showcase the performance of some particular steel or steels. I could make up a chart right now with all steels on it with all material properties. If I didn't actually justify any of the numbers in a way which would make them meaningful then why would anyone pay attention to it.

That chart by the way looks like it comes from data in "ASM Specialty Handbook: Tool Materials", edited by Joseph R. Davis. That source has the charts with numbers, tells what way they are measured and there are other steels and other tests. They are not nearly as flattered to the PM steels. It shows for example that simple A2 is far tougher than all of them and all of those steels are actually very brittle and their C-notch toughness is comparable to the v-notch toughness of steels like S7. The hardening of the non-PM steels is also likely less than optimal as for example D2 is as low as 59 HRC in some of them as is likely not cold treated and tempered cold.

[Donut]

Some people have dubbed XHP as stainless D2. If we consider XHP vs Cruwear, there are more models that were produced in both steels.

[TomAiello]

I have almost no experience with D2. Good experiences with both CruWear and XHP though. So yes, I agree that a discussion comparing CruWear with XHP would be more useful.

[spyderg]

There have been many posts here on CruWear and it is an interesting steel having been used a long time under many different names all the way back to VascoWear. In some ways it is easy to find data on it such as this :



But the problem is that such marketing information rarely tells you what they are measuring exactly, how the steels were hardened and what kind of precision they had so interpreting the results is problematic. If you do get some more data often you find that they are doing something like comparing adhesive wear resistance which can show very large differences in HSS vs Cr based steels but there is little correlation between that and abrasive wear which tends to happen in knife use.

The steel itself is an interesting blend of elements as it is a high carbon/tungsten modification to 3V (not that 3V came first, just looking at the difference) which an addition of Silicon. Silicon in small elements is in all steels (it is a deoxidizer) but in large amounts it is added for toughness (it is in the shock steels for example) because among other things it retard the formation of cementite at grain boundaries which happens in tempering (the carbon comes out of the martensite, forms epsilon carbide and then that dissolves and forms cementite). These cementite formations allow brittle failure hence suppressing them allows the tempering of the steel (makes it tougher) without causing the embrittlement of the cementite formation. Due to the higher carbon and tungsten it would be expected to have better abrasive wear than 3V and better hardness, and since this is mainly MC type carbides (small) and the silicon addition, it would be expected to have similar toughness.

But that still leaves the question as to how does it compare to a normal/workhorse steel like D2?

Well I have been looking for that for awhile, the problem is the massive amount of different tradenames doesn't make it easy, but you can save searches now and have results notified which is a help. Here is one such study :

"MACHINING SCIENCE AND TECHNOLOGY Vol. 8, No. 2, pp. 193–210, 2004, Kinematics and Wear of Tool, Blades for Scrap Tire Shredding"

It is an interesting work as it compares 4340 and D2 for such work and then CruWear to D2 extensively. It also mentions 3V and HSS and sort of implies possible future experiments. It also looks at chipping and chipping + wear. Interestingly enough there is no significant difference in chipping, but Cruwear is about 2:1 in terms of an improvement to resist wear. However there is not a lot of detail on how the steels were hardened, and it looks like both had significant retained austenite as the D2 blade was 56 HRC unworn and 59 HRC worn, compared to 58 and 61 for the CruWear. The results might not be as different with varying heat treatments of D2 which can achieve 62 HRC with full martensite.

It is an interesting steel and I am likely to pick up a Spyderco in it at some point. I have 3V, but the problem is that it is normally used in larger blades where I don't like how it performs at all as the grindability is far too low. I would be really interested if anyone has a CruWear from Spyderco and has a decent D2 blade (Dozier for example) and can see a significant difference in wear resistance, or other properties.

I have a Manix 2 cru-wear and 2 Brous Blades, (silent soldier flipper and bionic flipper). In my experience with them which is primarily light edc use, cutting up boxes, opening packages and such, but all have seen some use at work - heavier cardboard, shrink wrap, heavy duty plastic strapping. The steels both wear pretty evenly, (slight edge to the cru-wear) and sharpen pretty much the same too, (touch ups easier on the d2 and full sharpening easier on the cru-wear if that even makes sense? probably due to my skill or lack thereof in sharpening. I've used lansky stones and the worksharp on both steels) . I'm no where near an expert but I'd say they are pretty comparable overall.

[Cliff Stamp]

I'm no where near an expert but I'd say they are pretty comparable overall.

That is about what I would expect from the materials data which shows that the difference between them is comparable to the difference each has depending on how it is hardened.

CTS-XHP has the unique note of one of the few (if ever?) newish steels Dozier praised in comparison to D2.

[spyderg]

I'm no where near an expert but I'd say they are pretty comparable overall.

That is about what I would expect from the materials data which shows that the difference between them is comparable to the difference each has depending on how it is hardened.

CTS-XHP has the unique note of one of the few (if ever?) newish steels Dozier praised in comparison to D2.

I love the CTS-XHP on my Techno! Not only does it take and hold a great edge, it has really nice look and feel to it, at least the way it's finished on the Techno that is. Hit a few staples while breaking down some boxes and not a chip to be seen either. Can't say the same for the Cruwear, my 110v Native or s35vn on my ZT550 (I'm pretty rough on my tools sometimes but that's what I bought them for - to use them) although I'm not knocking those steels by any means. My k2 farid's 10v has been great and I'm currently carrying my newest, M4 Gayle Bradley but haven't put it through the paces yet.

[Cliff Stamp]

Can't say the same for the Cruwear, my 110v Native or s35vn on my ZT550 ...

In regards to chip resistance?

[Cliff Stamp]

Just as a point about how charts might not mean what you think and that you have to consider them carefully, just have a look at this :



Look at the wear resistance of 3V vs 10V vs 15V in the first series of bars, they are the standard as-tempered steels. 15V is higher than 10V which is higher than 3V but the difference is very small. Now this is based on actual data, it comes from an investigation of ion diffusion on PM steels to increase wear resistance. The reason why the difference is small is that they are measuring wear resistance by grinding a small pin made out of the steel vs extremely coarse silicon carbide sandpaper. The sandpaper is much more coarse than the carbides in the steel and thus wear is mainly by ploughing so it just scoops the carbides out of the way. If the abrasive was reduced to the size of the carbides (or similar to it) the difference between those steels would increase dramatically. As a side note, note the 3V steel when nitrided, has much higher wear resistance even than the 15V when not this is because it is wearing on a layer of vanadium nitride.

[Donut]

I have a factory Second Cruwear Military I'd be willing to loan you if you're really interested in doing your own tests.

[spyderg]

Can't say the same for the Cruwear, my 110v Native or s35vn on my ZT550 ...

In regards to chip resistance?

Yes, the others have sustained minor chipping from things like staples, the worst being on the 110v.

[Cliff Stamp]

Donut,

I appreciate the offer but I have two rules on that type of thing which make it unattractive / unreasonable for most people.

-everything is reported publicly, positive/negative
-there are no restrictions on the scope of work

Again, I don't want to make it look like I am ungrateful, but any knife you would considering sending would have to be one you really don't care if it is functional when it was returned.

I am most likely going to have a few customs made out of CruWear and 3V this year as I am curious about the high/low tempering behavior of both as I can't find any materials data on the question which interests me :

-If you take a cold work steel like D2 and make a hot work version of it, which one has the higher toughness at a given strength/wear resistance

I always thought it was the cold work version as everything I read implied it, Landes has data showing it is has the highest apex stability as well which supports the argument. But then I started to read that matrix HSS have a higher strength/toughness ratio.

Matrix HSS's are essentially HSS similar to M2 in hardness/martensite but just don't have the carbide volume.

[Cliff Stamp]

Yes, the others have sustained minor chipping from things like staples, the worst being on the 110v.

I can understand S110V, and ZT does odd things with hardening so that doesn't surprise me. It is curious that CTS-XHP show more chip resistance than CruWear. The edge angles and edge curvature/blade profiles are similar? Both have been sharpened more than once?

[spyderg]

Yup, everything been sharpened a couple of times, and touched up too. Manix2 Cruwear the most but it has seen the most use. It's been at different angles and never chipped bad, (too be honest I can't remember what angle it was at when it took the damage) just enough to snag a bit cutting thin or soft material. Nothing scientifc here, just observations from general use. You'd have to get same knife with different steels for that I'd guess. As a tough edc steel that needs little attention but is easy to work on when it does, CTS-XHP is my first choice. My ZDP189 dragonfly has slightly rolled edges that I haven't gotten around to fixing but from what I've heard it should be great about not rolling? Factory edge mind you... Nothing against any steel really, different steels in different roles. I used to have a nameless cheapo that didn't hold an edge well but could be sharpened on the grip tape on my pallet truck at work and be sharp as all **** for a day or 2! My M4 GB 3 days in pocket seeing only light use still shave sharp on factory edge. First steel I've had that patinas so quick, quite noticeable on thumb ramp and choil, much lighter on the blade but nice and even, nice colour so far. I always wipe my blades after use and don't usually get much of a patina. Cru-Wear has a touch, as did the 110v before I acid stonewashed it. Nothing on the Zdp189, or the 10v even though I thought they would have some by now. Oddly enough my Lava in vg10 has a light patina on it, came NIB that way. The ZT has been a solid performer when it does get carried which is not very often. When it does get used it's pretty hard. I bought it to be able to beat on, but I'd say I've used the Techno just as hard, it just feels indestructible. One time I actually cut through some paracord, hit a metal rack with the edge, dropped it on a rock and not so much as a scratch!? Anyways enough rambling, just want to say I enjoy reading your much more scientific reports on steels Cliff, keep up the good work.

[Cliff Stamp]

My ZDP189 dragonfly has slightly rolled edges that I haven't gotten around to fixing but from what I've heard it should be great about not rolling? Factory edge mind you...

ZDP-189 should have high resistance to rolling given the very high hardness and high carbide volume. However the initial edges which come with knives are often problematic for a few reasons so in general I would recommend not really paying much attention to how they perform specifically until the knife is sharpened at least a few times.

[spyderg]

My ZDP189 dragonfly has slightly rolled edges that I haven't gotten around to fixing but from what I've heard it should be great about not rolling? Factory edge mind you...

ZDP-189 should have high resistance to rolling given the very high hardness and high carbide volume. However the initial edges which come with knives are often problematic for a few reasons so in general I would recommend not really paying much attention to how they perform specifically until the knife is sharpened at least a few times.

Yeah, I figured it's just 'cause of factory edge, I've just had really good luck so far with Spyderco's coming with a good edge that didn't need any attention till after some decent use so i was surprised that light use rolled the Zdp. I don't carry it much as I usually carry 1 knife at a time, like to have it when I'm carrying something big like the Farid though, in case I have to use it out in public and don't want to scare anyone.

[Cliff Stamp]

Ha, yeah the Farid can create a decent reaction.

Spyderco does initial edges better than most, however on occasion they can be less than ideal and to be safe I generally sharpen at least a few times before forming a perspective. This also helps you to look at average behavior as well which makes it a little more stable.