zdp-189 vs Cowry X vs VG-10

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beera

Joined
Feb 16, 2006
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Hi All
This is a very informative article if you ever had this question. I searched your forum but there was nothing to explain the difference between ZDP and cowry. If there is I couldn't find it. Any thoughts on this?



Just like ATS-34 and 154 CM were the vogue of the nineties, VG-10 has now become the dominant steel in fine knives and for good reason. It is harder than ATS-34, more stain resistant, arguably tougher, has better edge retention and it is relatively cheap -- cheap enough that you can get $60 knives made out of it anyway.

But, recently the super steel focus has shifted to the enigmatic zdp-189. This Hitachi product is a truly ground breaking steel. The 3% carbon content and the ability to be hardened to RC 67 or 68 makes it incredibly hard and capable of rendering incredibly sharp edges. For comparison, "Normal" 440 stainless is about 56, ATS-34 is 59 and VG-10 is 61-62. ZDp-189 is up there with non-stainless crucible super steels like CPM-15V in terms of hardness! Normally, steel this hard will be very brittle and prone to chipping, but that is not so with Zdp-189. Why it is able to be hard and tough at the same time is probably the biggest mystery surrounding ZDp-189. Normally high carbon steel is also very low on chromium meaning they are not stainless at all. But Zdp-189 is 20% chromium - higher than even 440C stainless (16-18%)! So yes, it is a stainless steel!

Zdp-189 is however very hard to come by. Not only is it expensive, Hitachi is not selling it to anyone. Only a select group of manufacturers are allowed access to it. To the best of my knowledge, they are all Japanese at this point. These manufactuerers are also the ONLY ones allowed to heat treat it -- leading to the speculation that a lot of the secrets behind its performance is related to not just its composition but how its heat treatment has to be handled. This remains a closely guarded secret by Hitachi and by their close circle of select manufactuerers.

Anyway, recently Daido Corporation came out with its own copy of Zdp-189. They call it Crowy X. It also has 3% Carbon and 20% Chromium, but its other compositions supposedly differs from Zdp-189. Neither manufactuer has been forthcoming as to what exactly goes into their supersteels so this is impossible to verify at this point. Crowy X is no cheaper, but at least Daido is a lot more liberal about who is allowed to buy it directly and work it. A RC hardness of 67 is claimed for Crowy X.

Anyway... that ends my 2 cents worth of knowledge on the topic. Really, that is all I know at the moment... perhaps someone else will be able to deliver me from my ignorance! All comments welcomed1

http://216.91.137.210/ubbthreads/showflat.php/Cat/0/Number/7763/page/3/fpart/1/vc/1
 
The 2 top-end steels used in Japan are Cowry X and ZDP-189.

ZDP-189

This is what knifemaker Glenn Waters says about it: "ZDP-189 Hi tech stainless made by Hitachi maintains balance between its high hardness of RC 67 and its ductility. It was developed solely for the purpose of knives. It is a powdered metal, and has 3% carbon, which gives it a very high hardness and yet still remains ductile. A great knife steel but expensive. Its high hardness and strength make it great steel for working knives because It can cut through dried bamboo without marking or scratching the blade. Is recommended for heavy work like chopping.
"

3% carbon!!! Dang!!!

What Sal Glesser (Spyderco) says: "ZDP-189 is made by Hitachi. Information is more difficult to obtain. We list specs in our steel charts but this info is IMO, not complete. I think there is more stuff in it, but Hitachi has made some great steels and their metalurgical skill is exceptional, so my questions are somewhat insignificant. They have very exacting heat treating requirements and only a few heat treaters in Japan are authorized to heat treat ZDP-189. I imagine that Hitachi has provided special instruction and meticulous controls. The knives that we tested in edge retention placed it with S90V. Very impressive. It was in fact Rc-65. Also impressive and no chipping was experienced."

Cowry X

According to Glenn Waters: "Very similar to the above ZDP-189 in that its hardness is RC67 and takes a great mirror polish but a foggy mirror polish, A great blade steel but expensive. Produced through gas atomizing, Hot Isostatic Pressing (HIP) which is very abrasive resistant."

From Chuck Bybee: "The people who are making comments about the steel: What is your experience with Cowry X steel? Do you know how it is made? Do you know that it is a powdered metal that has been HIPed four times! The CPM steels are HIPed once. Cowry X may be the finest grained and best stainless ever made. It can be polished so it looks like mercury. Ken Onion made a knife from it. He cleaned four animals and the edge was not affected. It passes the brass rod test at 64 Rockwell. The raw steel costs more than most kitchen knives. I wish Cowry X were still being made."


Cowry Y

This is a semi-stainless variant on Cowry X. Ken Onion holds it in high regard: "Cowry-Y is the best blade steel I have seen at holding a super keen edge the longest. I can also get it sharper than anything else.I was given a few coupons of it to try a couple years ago and just pushed it aside untill a few months ago when I decided to give it a try . Now I am actively trying to find a source for it as I am very impressed with this material. The steels I usually use are 440-C,BG-42 and S30V which are all great choices so I am not doing a commercial for cowry Y. I just say it as I see it." http://www.knifeforums.com/ubbthreads/printthread.php?Board=Kitchen&main=416977&type=post
 
Dang great info guys! Sweet!Love my Calypso Jr. in ZDP 189 and would love to get my hands on a McHenry-Williams edition of the ZDP 189. Sharp is no longer just a passion ... it's an obsession. :D
 
beera said:
Zdp-189 is however very hard to come by. Not only is it expensive, Hitachi is not selling it to anyone. Only a select group of manufacturers are allowed access to it.
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ZDP-189 is available for $80 per pound. How much do you want to buy? ;)
 
Chuck Bybee said:
ZDP-189 is available for $80 per pound. How much do you want to buy? ;)
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But it is less then CPM 10V on my experience.

HT is trivial - same as for ATS-34.

It is very available no any secrets - I am wondering if it is so strict to sell and if Hitachy not selling it to everyone how regular guy like me was able to by it without any problem?

It is some kind of hype I bet. Somebody making money this way, but it is easy to buy in Japan - I did it and Phill Willson did same way I did - no problem. Why it was so many trouble for McHenry-Williams to do this still puzzle me - buying kitchen knives, cut blades out of it, send it back to Japan for HT...

I think it is up to honest supplier in Japan. Only one thing you need - somebody speaking Japanese to coomunicate with supplier or better somebody in Japan who can buy it there and send to US.

Thanks, Vassili.
 
Language, cultural differences, suspicion, communication, politics, competitiveness, pride, rumor, marketing smarts, buzz, hype, true performance...they're all cause for ZDP-189's current place at the top of the Hot Blade Steel of the Moment list.
 
I find the first article very misleading. Steels don't have a fixed hardness. Their hardness depends on the heat treat. Sure, different steels have different trade-offs at different hardness. But just look at S30V, while some will run it 56-57 others think it performs better at 58-59 while others again say it truly shines at 60+. So is this now a harder or a softer steel than ATS-34???

While ZDP can be run very hard apparently without getting overly brittle, fact remains that at 66Rc ZDP does not have the impact toughness as S30V or VG-10 or even ATS-34 run at around 60 Rc, let alone the toughness you can coax out of many standart tool steels A2, 52100, 1095, not to mention lower carbon non-stainless steels like 1060.

Also, the 20% Cr do not directly correlate to the corrosion resistance. Sure it is a stainless steel because the designation means nothing but that you have 13%+ Cr content. ZDP also contains 3% C, which makes it, according to definition a CAST IRON! Chances are, that a great portion of the Cr is tied up as chromium carbides, which do not increase corrosion resistance. The Cr "steals" the carbon or the carbon "steals" the chromium however you want to look at it.

Personally, I really like the ZDP steel, but I think it is important not to get too carried away over it and to look for what it is optimized.
 
Well I think by 67-68 RC they mean thats how hard it is dead hard (right after quench in a suitable medium). Thats amazing for a stainless steel, thats even higher then 1095 is dead hard.

It seems like these steels are breaking all the rules about what stainless should be like. My question is though, at 80 dollars a pound your paying 80 percent of that for its stain resistent qualities, is it really worth it?

I mean, a properly heat treated 1095 knife will do everything it can right?
 
I've posted this in the past and it's worth noting again. ZDP-189 is not a "new" steel. I saw my first metallurgical report on this steel in a 1989 report. It is relatively new to the US market. Why? Hitachi has very limited PM steel capacity. They had reserved most of their limited production of ZDP-189 to the home market. Obviously, things have changed and here it is in the US. The data on the material was what you would expect. At low hardness levels it is average in toughness with other stainlesses and at high hardness levels it was less tough but still reasonable (on par with high hardness high speed steels). Very high carbide content level at around 25-30 percent, all chromium carbides. For comparison the CPM 10V mentioned above has roughly 20% carbide content, all vanadium carbide.
 
Satrang said:
I've posted this in the past and it's worth noting again. ZDP-189 is not a "new" steel. I saw my first metallurgical report on this steel in a 1989 report. It is relatively new to the US market. Why? Hitachi has very limited PM steel capacity. They had reserved most of their limited production of ZDP-189 to the home market. Obviously, things have changed and here it is in the US. The data on the material was what you would expect. At low hardness levels it is average in toughness with other stainlesses and at high hardness levels it was less tough but still reasonable (on par with high hardness high speed steels). Very high carbide content level at around 25-30 percent, all chromium carbides. For comparison the CPM 10V mentioned above has roughly 20% carbide content, all vanadium carbide.
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That and you can't buy ZDP-189 in the U.S.
 
tsdevanna said:
CPM10V is around $18.00 - $25.00/lb. depending upon thickness
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I bought one from Crucible directly and it was twice then what was ZDP-189, I am not sure what weight was, but it also was harder to get in reasonable for knife thickness.

What is your source of CPM10V? I'll like to buy some.

Thanks, Vassili.
 
nozh2002 said:
What is your source of CPM10V? I'll like to buy some.
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Vassili,

I'm pretty sure tsdevanna is Scott Devanna from Crucible.

If you want some 10V let me know. I'll be placing another order with Crucible in a few months.
 
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