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

I really enjoyed this one. Not steels I use, but I love learning about the alloying effects.

I did a few heat treats with S90v for toughness testing, and have more here for additional tests.

Interesting thoughts on the nitrogen steels.
 
I love the ZDP-189 found on my Stretch 2. Cuts forever and sharpens up easy with DMTs.

It also stains/rusts after one day in use as a pocket EDC, but the extra maintenance is well worth the performance gains.

Thanks again for putting this all together and sharing your work.
 
I couldn’t disagree more with your conclusions on the corrosion resistance and toughness of ZDP-189. I have been EDCing 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 notice 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 90, 110, and 125, and the edge retention of 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.
 
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I made a ZDP-189 and a Cowry-X kitchen blades many years ago. I still use the ZDP knife. The Cowry was a gift, and last I heard it was working wonderful.
 
Larrin, a very interesting article! as always, moreover. I also found very interesting what you write in this article in reference to the possibility of having the CPM154 at 64HRC and more. Please can you show me your way to achieve this. Thank you.
 
mknife said:
Larrin, a very interesting article! as always, moreover. I also found very interesting what you write in this article in reference to the possibility of having the CPM154 at 64HRC and more. Please can you show me your way to achieve this. Thank you.
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The heat treatment process is all laid out in the article. For me peak hardness was 2025F for 20 mins, plate quench, liquid nitrogen, and 2 tempers at 250F.
 
ZDP-189 rust resistance is about D2 level from my experience. It does sharpen noticeable more difficult compare to M4, S30V, M390 etc.
 
Larrin said:
The heat treatment process is all laid out in the article. For me peak hardness was 2025F for 20 mins, plate quench, liquid nitrogen, and 2 tempers at 250F.
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Thank you!
it's true it's all written, I had made a bit of confusion in the translation and in the conversion of the temperatures.
 
I’ve had a rockstead higo in zdp but not enough use to comment one way or another.

Tim Wright has used Cowry and Koji Hara as well.

thanks for the research and write up.
 
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