ZDP-189 and Cowry-X: Overrated or Super Steel?

bravo for telling it like it is... I've been a critic of anything with 1.5% carbon and higher, and zdp189 having double that amounts to basically cast iron - brittle nonsense (imho)

anyone using it should expect chipping edges continually, or, if the geometry really is thick enough to help minimize chipping, you'll be so thick you'll never slice well
it still surprises me that rockstead uses it - I'd love to see the return/replacement %'s they get... of course being so expensive I doubt many see any real use ; )

outside of rockstead, the only other mfg that uses it is spyderco, which I'd love to see the %'s also
 
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dirc said:
bravo for telling it like it is... I've been a critic of anything with 1.5% carbon and higher, and zdp189 having double that amounts to basically cast iron - brittle nonsense (imho)

anyone using it should expect chipping edges continually, or, if the geometry really is thick enough to help minimize chipping, you'll be so thick you'll never slice well
it still surprises me that rockstead uses it - I'd love to see the return/replacement %'s they get... of course being so expensive I doubt many see any real use ; )

outside of rockstead, the only other mfg that uses it is spyderco, which I'd love to see the %'s also
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I've seen other manufacturers use ZDP-189 (e.g. Kershaw/ZT).
 
There are of course other Japanese companies that have used ZDP-189 and Cowry-X. I think Cowry-X is no longer made though.
 
Where did you get your samples of ZDP-189 from? Is there a possibility that the source could have compromised samples? I have not experienced any rust issues with my ZDP knives. Also, my ZDP knives are convexed, -there is some but not much of chipping going on and they slice perfectly.
 
ridnovir said:
Where did you get your samples of ZDP-189 from? Is there a possibility that the source could have compromised samples? I have not experienced any rust issues with my ZDP knives. Also, my ZDP knives are convexed, -there is some but not much of chipping going on and they slice perfectly.
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The steel is from Barmond and no, there’s nothing wrong with it.
 
I've gotten some light spotting on my ZDP-189 Delica before. Especially inside the thumb hole since it has a rougher texture in there. I haven't experienced chipping out of mine during the years that I had it in my rotation, but I'm pretty cautious about my methods of use and I remember seeing a lot of reports of it when it became a regular steel option.
 
FortyTwoBlades said:
I've gotten some light spotting on my ZDP-189 Delica before. Especially inside the thumb hole since it has a rougher texture in there. I haven't experienced chipping out of mine during the years that I had it in my rotation, but I'm pretty cautious about my methods of use and I remember seeing a lot of reports of it when it became a regular steel option.
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Many people have confirmed corrosion in their ZDP-189 knives. Of course a couple other people have told me I’m wrong and that it’s stainless.
 
I'd call it semi-stainless, as it's definitely a good step above D2, which often gets called such. Certainly more stain resistant than low-alloy steels by a strong margin, but it's at the dead bottom of steels I'd be willing to admit into the stainless classification. Kind of one of those matters of where you draw the line, eh? It's somewhere in that nebulous zone between the two camps and regardless of if it gets considered as the one or the other, it's going to be a kind of murky member. :D
 
I like ZDP. Takes a really good edge and holds it fairly well. I'd stick it between S30V and M390 in edge retention, but unlike most other super steels it plays very well with a refined edge. For corrosion resistance I'd say it's about equal to D2, it will resist some corrosion but if put away wet it will definitely start spotting with relative ease, and it isn't terribly hard to stain.

My only real complaints with ZDP are that it's rare, and is definitely not a bastion of toughness, but that could also be from me always sharpening it to as refined as I can get it.
 
dirc said:
They don't seem to have any current models that use it, at least that I could see... which ones have it?
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There have been a bunch, but off the top of my head: Blur, Leek, Chive, ZT 450, etc.
 
I believe Fallkniven still has a knife made in Cowry- x steel and that knife is really expensive.
 
Ichiro Hattori of Seki is the only well known knife maker who uses Cowry-X (and even sometimes Cowry-Y). The reason that some Fallkniven knives are Cowry-X is that Hattori makes all of their fixed blades.
As for folders, Hattori makes the H51, which is the Kershaw 1050 which he used to make in Cowry-X and he also made blades for
A. Marfione.
 
Zdp-189 used in my Spyderco Dragonfly II and Caly 3 hasn't left me wanting when it comes to toughness. The Dragonfly has had the odd bit of spotting show up on the blade, but no pitting or anything serious, rubbed out with a kitchen scrubby. No major chipping to report, maybe some minor stuff but nothing serious enough that it has been etched in my memory/ remained on the blades after touch ups on the sharpmaker. The blades have been used for cardboard, heavy plastics, wood whittling, but I am conscious to keep from twisting when using due to this thought that chipping could be an issue.
 
It’s good to see some actual testing with zdp.
I was always suspicious of a ‘stainless’ steel with so much carbon. It didn’t make sense to me
 
Steel heat treatment and edge geometry are as important as steel composition. From the anectdotal information on problems with ZDP performance, they seem to be isolated with certain companies and are not as prevalent as they used to be. This would leave one to believe that heat treat and edge geometry has been optimized since the early 2000s.

I have a Wiliam Henry Tom Brown Quest in ZDP. It is the best performing edge I have. I use it a lot, particularly in the kitchen. I've used it so much, the button lock stopped keeping it fully closed and it needed to be repaired. A review by Bladeforum member Dexter Ewing can be found here: https://www.trackertrail.com/publications/inthenews/WHK_Brown.pdf

This knife has been exposed to water, lemons, pickles, onions, limes, etc. I use it to cut up chickens including cutting out the back to barbecue chickens in one piece spread out on the grill. After use but not during use, it gets washed off with soap and water and dried inside and out with a paper towel. The edge has never chipped. There is ~1cm of ZDP exposed (it's san mai blade) this exposed ZDP has never discolored, rusted, etc. Leading me to conclude ZDP is tough and is stainless, for example D2 would discolor and possibly rust under the same conditions of use.

When it comes to sharpening, it doesn't really need it. I have "touched it up" using the Spyderco fine rods, but it never really needed it. Without abuse and at 65-67 RC this isn't too surprising. Using the finger nail test, there has never been any chips.

So in my experience this conclusion from the article is incorrect: "ZDP-189 is an interesting steel because of its high hardness capability despite being advertised as a stainless steel. However, it has low toughness, and corrosion resistance experiments confirm that the steel is not actually very stain resistant...Because of the false advertising of this steel as being “stainless” I give ZDP-189 the Knife Steel Nerds “Most Overrated Steel” award."

William Henry uses a lot of ZDP and the internet does not contain the same complaints about William Henry's performance as there are for other manufacturers. In addition, Matt Conable, the brains behind William Henry, has had a lot experience in heat treat and knife design that other firms may not have. This has led me to believe over the years that not every company can get ZDP "right" but William Henry can.

For the tests in the article, how does the heat treat procedure used in this test compare to William Henry's method? From the link to corrosion testing it appears the same heat treat was used for all steels for corrosion testing. Shouldn't a heat treat be customized to the steel and application?

Per article, the corrosion testing was done using a 400 grit finish. That's similar to the finish on a Spyderco Police handle, certainly not polished. Possibly 400 grit was chosen to promote oxidation, but it's a rough finish for the steel's use as a knife blade. Maybe 400 grit is not optimum for ZDP, William Henry knives are polished to a finer surface than 400 grit. Could the finish have biased the results?

Edge geometry is not discussed in the article, but is key parameter in toughness. How does the edge geometry in this testing compare to William Henry's edge? Edge geometry could be the source of variability between manufacturer's success with ZDP.
 
I have had a similar experience with a William Henry Tom Brown Quest. I couldn’t disagree more with your conclusions on the corrosion resistance and toughness of ZDP-189. I have been ECDing ZDP for over 20 years and have had no problem with corrosion or chipping. My blades have a ZDP core (67HRC) with a 420 cladding. I have noticed more light rust on the cladding than on the core. In neither case was there pitting.
I do food, rope, cardboard, wood, wine bottle foil, etc. I have 30, 60, 90, 110, and 125, and the ZDP is comparable in my experience. The ZDP has knocked all the other stuff out of my pocket in part because of the ease of sharpening on Shapton Glass Stones and the Spyderco Sharpmaker.
 
tiguy7 said:
I have had a similar experience with a William Henry Tom Brown Quest. I couldn’t disagree more with your conclusions on the corrosion resistance and toughness of ZDP-189. I have been ECDing ZDP for over 20 years and have had no problem with corrosion or chipping. My blades have a ZDP core (67HRC) with a 420 cladding. I have noticed more light rust on the cladding than on the core. In neither case was there pitting.
I do food, rope, cardboard, wood, wine bottle foil, etc. I have 30, 60, 90, 110, and 125, and the ZDP is comparable in my experience. The ZDP has knocked all the other stuff out of my pocket in part because of the ease of sharpening on Shapton Glass Stones and the Spyderco Sharpmaker.
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I figured you might weigh in, since I've seen pictures of your Quest and you use your knives. IIRC you have a sweet custom anodization.

Do you have any ZDP from a maker other than William Henry, if so, same good performance?
 
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brownshoe said:
I figured you might weigh in, since I've seen pictures of your Quest and you use your knives. IIRC you have a sweet custom anodization.

Do you have any ZDP from a maker other than William Henry, if so, same good performance?
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I have couple of G Sakai Trekkers with ZDP main blades and 3 Spyderco Enduras with ZDP blades. I haven't used them much because they can't displace the W/H.
 
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