Any downsides to ZDP 189?

WYK said:
You don't have to guess - Chromium and Carbon are NOT tough. They are hard and brittle. If you have a steel with more Chromium and Carbon, and nearly every other aspect is similar, it will be less strong and more brittle. All the charts I have seen for ZDP show it doesn't even have Mn(Manganese) which helps make a metal tougher, and is included in ATS-34, 154CM, 5160, M2, D-2, etc. If ZDP lacks this element, it's likely never going to be terribly tough at any usable hardness. WYK
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All I was saying is that if we had the hardness at two points we could guess what it was in between.

Maybe ZDP is much more brittle than ATS at 60Rc, but maybe it's only a little. Can you tell based solely on composition? Does the method used for alloying make any difference (say like in crucible's famous S30V)?

I think the problem is that there is very little hard data on ZDP at the moment, so we'll just have to wait for a flood of user opinions.
 
Artfully Martial said:
What does the graph mean?
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Charpy tests take a big hammer and smack it into a bar of steel and see how much energy it takes to crack the steel in half. With knives they correspond to how well the edge, tip and blade as a whole take very hard impacts.

hardheart said:
why harden above 60 on a knife, or use a steel that needs to be hardened to that level for edge retention?
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You need high hardness for high edge retention for a lot of cutting on a lot of materials.

klattman said:
The only way you can say one steel is tougher than the other is to compare them at the same hardness.
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Steels should be compared at the hardness which gives them their optimal performance, this isn't at the same hardness for all steels.

WYK said:
Is Spyderco laminating it? I hope so. Have fun sharpening it if it isn't.
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This is more dependent on the shape of the edge than its composition. I have knives made out of 1095 at 66 HRC, M2 at 65 HRC and O1 at 63.5 HRC which all sharpen trivially.

-Cliff
 
Cliff Stamp said:
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Steels should be compared at the hardness which gives them their optimal performance, this isn't at the same hardness for all steels.
...
-Cliff
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It isn't the same hardness for all applications either.
Problem is, how you define 'optimal performance' depends highly on the application.

If ZDP is _only_ good at 67Rc and ATS34 is _only_ good at 60Rc, then you are forced to compare apples to oranges, so I definitely see your point.

Curves which show toughness vs. hardness would allow you to pick the best steel for the application. How can you _know_ ZDP is useless at a lower hardness? Well someone does or else it wouldn't be run that hard... but that's not very satisfying to the end user. ;)
 
3Guardsmen said:
I took it to mean that ZDP-189 scored considerably lower in toughness (and higher in hardness) in the CHARPY test than ATS-34 (at 60 RC). Meaning basically that it would tend to be more brittle (at the tested RC hardness) than the other two steels (ATS34 & 440C) tested.

Best wishes,
3Guardsmen
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How or what does a charpy test measure exactly? Is a bar of steel suspended over the end of something and then whacked until it breaks? Or is it set on an anvil and whacked until it cracks and the Charpy Test counts the number of whacks?
 
klattman said:
It isn't the same hardness for all applications either.
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Generally you don't move the hardness of a steel around to match your needs, you get better performance from switching to a tougher steel than underhardening another one for example.

How can you _know_ ZDP is useless at a lower hardness?
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Not useless, just that strength is highly linked to hardness and that its true standout ability is its high hardness which is rare for stainless. It is going to be used on light cutting knives anyway, not heavy choppers, so you want strength and not toughness .

DGG said:
How or what does a charpy test measure exactly?
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A bar of steel is hit with a hammer and how much energy it takes to crack it in one hit determines its toughness. The bar can be notched in various shapes and held in a vew positions depending on the type of tests, but they all basically measure the resistance to a sudden very hard impact, similar to dropping your knife tip first onto concrete for example, or plowing the edge into a rock which is hidden under some scrub.

-Cliff
 
klattman said:
The only way you can say one steel is tougher than the other is to compare them at the same hardness.
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Not true. Or at least not reasonable. Different steels exhibit different levels of edge retention even if hardened to the same level. If ZDP-189 turned out to be as tough at, say, 60 HRC as ATS-34 at the same hardness, we still don't know if it holds an edge as well.
 
Quiet Storm said:
Not true. Or at least not reasonable. Different steels exhibit different levels of edge retention even if hardened to the same level. If ZDP-189 turned out to be as tough at, say, 60 HRC as ATS-34 at the same hardness, we still don't know if it holds an edge as well.
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No, we don't know if it does or not, but we could find out.

The problem is too many interdependent variables, so you can only compare steels if you qualify the variables. I agree that it may be unreasonable to compare steels at the same hardness (eliminating all but one variable), but it's also somewhat unfair to compare steel properties at vastly different hardnesses, since changing the hardness of the 'better' steel to match the other may make it much much worse.

For example, saying ZDP is too brittle is unfair because ATS34 at 67Rc may be just as or more brittle. So it may not be a property of the _steels_ in question, it may be completely dependent on the hardness and not on the steel composition.

Steel A is better than steel B is much more complicated than one charpy or catra test can demonstrate. :)
 
Cliff Stamp said:
This is more dependent on the shape of the edge than its composition. I have knives made out of 1095 at 66 HRC, M2 at 65 HRC and O1 at 63.5 HRC which all sharpen trivially.

-Cliff
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None of those steels have 20% Chromium AND 3% Carbon in them. They are Carbon steels, which as you know, are generally easier to sharpen than stainless for a given hardness rating.

WYK
 
I only care about the properties of the steel I'm actually using. I don't care about the theoretical integrity of a steel at this or that hardness. Just the one the knife comes in. These issues are important for the folks making the knives, just not for me. I don't get to decide.
 
Has no one read Blade magazine. They reviewed the William Henry and said it was great! No chipping even when heavy carving was involved. I say look at real world experience not charts. :barf:
 
WYK said:
None of those steels have 20% Chromium AND 3% Carbon in them.
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Chromium carbide is *very* soft compared to the higher alloy carbides, I also have very hard blade blades in CPM-10V which has a very low grindability due to the high vanadium content.

I also have a Calypso Jr. in ZDP-189, it is no problem to reshape the edge with the right stones, you don't need diamonds either, SiC waterstones will handle it readily.

They are Carbon steels, which as you know, are generally easier to sharpen than stainless for a given hardness rating.
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Lots of tool steels have a much lower grindability than cutlery stainless steels, and grindability should never be an influence to you when sharpening anyway.

The carbon vs stainless general abilities that are cited usually only hold for underhardened pure carbon steels. They don't apply to harder version of the same carbon steels, and they certainly don't apply to tool steels in general.

klattman said:
For example, saying ZDP is too brittle is unfair because ATS34 at 67Rc may be just as or more brittle.
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ATS-34 can't get that hard, it maxes at 65 HRC with oil+cold and a very low temper. I have used a Calypso Jr. in ZDP-189 for some harsh work, dropping the tip into concrete, dynamic metal cutting, etc., it isn't significantly more brittle than other high carbon stainless steels. I would not make a chopper out of it, and would not want to do any other heavy impact work like batoning, but it isn't a concern for a knife to be used for cutting.

outlaw918692000 said:
Has no one read Blade magazine. They reviewed the William Henry and said it was great! No chipping even when heavy carving was involved.
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How thick was the edge and at what angle was it ground? This work by the way has nothing to do with impact which is what the charpy chart illustrates.

-Cliff
 
Cliff Stamp said:
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ATS-34 can't get that hard. I have used a Calypso Jr. in ZDP-189 for some harsh work, dropping the tip into concrete, dynamic metal cutting, etc., it isn't significantly more brittle than other high carbon stainless steels. I would not make a chopper out of it, and would not want to do any other heavy impact work like batoning, but it isn't a concern for a knife to be used for cutting.
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-Cliff
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Well, that's what I'm trying to say. It's unfair to condemn ZDP because it is x times more brittle, when other steels cannot even get that hard in the first place.

My Calypso Jr. is fine also...is it worth the extra cost? I'm not sure.
 
Because the steel junkies wanted to try ZDP. S90V has been around and used for a long time.

sal
 
Sal Glesser said:
Because the steel junkies wanted to try ZDP. S90V has been around and used for a long time.

sal
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OK, I want - CPM S90V, CPM 10V, CPM 9V, YSS YXR7, YSS ZDP4, YSS ZDP247, CPM M4. I am not sure is CovryX different then ZDP-189? There is also CovryY.

M2 and 3V I already have in BM 710 and Fehrman PM, but I want more.

Also I wand wootz and steel-ceramic in production knife.

I think I foget something else... Well, I will add some more stuff later (I heart that small traces of Zerium make steel really perform).

Thanks, Vassili.
 
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