How does ZDP 189 work?

DeadboxHero

DeadboxHero

Knifemaker / Craftsman / Service Provider
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ZDP 189 notably has 3% carbon and 20% chromium.

It also has the ability to be heat treated to 67hrc without shattering like glass at the edge.

My question is how does all this come together?

Are chromium carbides able to lock into the iron matrix better then vanadium?

What allows for both hardness and toughness?
Is there something intrinsic about zdp189 that allows for 67hrc?

Thanks for the info guys.
 
I'm far from an expert, but my guess would be the huge amount of carbon allows for the extreme hardness and the PM process probably helps avoid the shattering like glass bit. That said, I've never heard ZDP referred to as particularly tough.
 
insipid is correct I believe, I also have never heard of or referred to zdp as tough.
 
The only Charpy numbers I could find were kind of obnoxious as they were testing ZDP at 67 Hrc and they didn't specify the units used so I'm not sure if it was in foot pounds or joules. Either way it was about 8, which isn't very impressive as far as steels go.
 
LOL single digits, nice. For comparison s7 is somewhere around 120 I believe... been a while since I read up on it. And 1095 is in the high 20's to mid 30's if i'm not mistaken.
 
I believe a large part of it is that it is a powdered steel, and is thus very uniform. This gives it the maximum possible impact resistance (for that steel) due to the uniform grain structure. As to what gives it the incredible hardness and retention, that's the carbon. It has very low impact resistance compared to most steels, however.

Not something I'd really want in an EDC knife. In my climate and with my uses, it would be chipped and rusty within a week.
 
shinyedges said:
LOL single digits, nice. For comparison s7 is somewhere around 120 I believe... been a while since I read up on it. And 1095 is in the high 20's to mid 30's if i'm not mistaken.
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Depends on hardness, but yeah. I figured out the chart was in joules, and 3V tops out at 53 joules at Hrc 62. That's bloody hard and tough. Hrc 67 is, admittedly, MUCH harder than Hrc 62, but 8 joules sure isn't anything to write home about in steel terms. That said, I've tagged plenty of staples and nonsense with ZDP blades and have never suffered anything close to catastrophic edge failure or even had much damage. I wouldn't pry or baton with the stuff, but it's tough enough for most EDC use.
 
Awe, let me be specific, tougher then other available knife steels at the same 67 hrc

I watched the Rockstead knife test video.
The guy whacks a piece of wood with the knife then proceeds to cut stuff with no noticeable damage.
 
Definitely depends on hardness, and that's why I love me some 3v... not many steels can reach that hardness AND maintain extreme toughness.. if 3v is at 53 joules at 62rc then at 58 or 60rc I imagine it would be even tougher and still hold an edge pretty damn well.

I had a delica in zdp 189 and like you had no catastrophic failures but I wasn't exactly hard using it either.
Insipid Moniker said:
Depends on hardness, but yeah. I figured out the chart was in joules, and 3V tops out at 53 joules at Hrc 62. That's bloody hard and tough. Hrc 67 is, admittedly, MUCH harder than Hrc 62, but 8 joules sure isn't anything to write home about in steel terms. That said, I've tagged plenty of staples and nonsense with ZDP blades and have never suffered anything close to catastrophic edge failure or even had much damage. I wouldn't pry or baton with the stuff, but it's tough enough for most EDC use.
Click to expand...
 
DeadboxHero said:
Awe, let me be specific, tougher then other available knife steels at the same 67 hrc

I watched the Rockstead knife test video.
The guy whacks a piece of wood with the knife then proceeds to cut stuff with no noticeable damage.
Click to expand...

Problem is I don't know of many other commonly used knife steels that can get to 67 Hrc. That kind of hardness is almost exclusively the range of exotics. Most other steels with great wear resistance rely more on high carbide content and the hardness of said carbides than they do on just being run stupid hard. That also means they can offer similar, or superior, edge retention to ZDP-189 while also maintaining higher levels of toughness and corrosion resistance.

ZDP is good stuff, but for my money there are just steels that fit my needs better.
 
shinyedges said:
Definitely depends on hardness, and that's why I love me some 3v... not many steels can reach that hardness AND maintain extreme toughness.. if 3v is at 53 joules at 62rc then at 58 or 60rc I imagine it would be even tougher and still hold an edge pretty damn well.

I had a delica in zdp 189 and like you had no catastrophic failures but I wasn't exactly hard using it either.
Click to expand...

I actually think 3V is around twice that tough at Hrc 58. That stuff is just ridiculous. And 4V seems awesome too, but I don't have any of that to play with yet.
 
I've been reading about vandis 4e for awhile now, been itching to try something in it. Supposedly very tough with excellent edge holding, similar to 3v. 4v is another I want to try, is it crucibles version of vandis 4e?
Insipid Moniker said:
I actually think 3V is around twice that tough at Hrc 58. That stuff is just ridiculous. And 4V seems awesome too, but I don't have any of that to play with yet.
Click to expand...
 
There are already a lot of threads on ZDP, try doing a search. You will definitely find some interesting reading.
 
Thanks Rev, My google fu is weak, just looking for more specific metallurgy answers. The questions are burning holes in my brain! Ahhaaa!
 
The specificity of the questions has been covered, believe me. Search for answers in the Spyderco forum. There are discussions going back 6 years, lots of good information and part of the fun is being able to read what was once written and possibly thought to be true versus what we know now. That is how we learn. My favorite ZDP knife of all time that is readily available and affordable is the Stretch/Endura. Right around $100 gets you some good stuff.
 
DeadboxHero said:
Awe, let me be specific, tougher then other available knife steels at the same 67 hrc

I watched the Rockstead knife test video.
The guy whacks a piece of wood with the knife then proceeds to cut stuff with no noticeable damage.
Click to expand...

That's not ZDP-189 they use in that video, it's YXR7 that performs that way.

YXR7 is optimized to maintain a high hardness (~around 65hrc) and still maintain a great amount of toughness. ZDP-189 would chip under that kind of use when ran at 67hrc, that's why the videos where they are push cutting soft materials (ie. Manila rope, phone books) are being done with their ZDP.
 
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