Any downsides to ZDP 189?

stevekt · Oct 2, 2005

There is no downside to ZDP-189. It is the answer to all out prayers. It will cure cancer and allow blind men to see. Chris Reeve has refused to build a ZDP Sebenza because it would be borderline blasphemy for man to create a tool fit only for the gods.

3Guardsmen · Oct 2, 2005

db said:
WYK are you saying that Sal used a steel without knowing everything reasonable about it in his knives he is selling? Kind of hard for me to beleive.

If you actually read WYK's post (and the posts and links before it) you would see that he quoted (look at the quotation marks) the article's quotation of Sal. That is not a new article either (2/05).

Best wishes,
3Guardsmen

nozh2002 · Oct 2, 2005

howiesatwork said:
Downsides?
We cannot get the info for heat-treating it, and can't buy it in bar or sheet form, so we cannot utilize it in the US market, except as a finished product from Japan.
That's what it looks like to me...ICBW,BIPN.

HT is as for ATS-34 and I was able to get one bar. I posted about it ages ago. Not only me but Phil Willson was able to buy it from Japan without any problem.

I asked my friend from Japan about WH buying kitchen knives to make his and he sad that it sounds rediculos. It is easyly awailable if you try.

Thanks, Vassili.

Here my topic:

http://www.bladeforums.com/forums/showthread.php?t=357804&highlight=ZDP189

It looks like everibody saing that it is impossible to buy but nobody really tried...

Artfully Martial · Oct 2, 2005

So what's the graph mean again?

3Guardsmen · Oct 2, 2005

Artfully Martial said:
So what's the graph mean again?

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

Keith Montgomery · Oct 2, 2005

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.

It didn't score higher in hardness. Charpy testing does not test hardness. The 67.5 HRC value was given to let people know what hardness the steel was at when it was tested, so that people will have a point of reference in comparing the steels tested. Charpy testing is done to find out the impact toughness of a material. The lower the impact energy needed to fracture the material, the more brittle it is. The hardness that a steel is tested at will definitely make a difference to the charpy value.

Keith Montgomery · Oct 2, 2005

Since Spyderco does charpy testing, maybe Sal can give us the Charpy value of ZDP-189 at 63-64 HRC.

hardheart · Oct 2, 2005

why harden above 60 on a knife, or use a steel that needs to be hardened to that level for edge retention?

Artfully Martial · Oct 2, 2005

So this would imply that our particular ZDP is somewhat more brittle than another premium SS at the moment?

robertmegar · Oct 2, 2005

Artfully Martial said:
So this would imply that our particular ZDP is somewhat more brittle than another premium SS at the moment?

Not implied, that is an actual test result. It IS more brittle. Very hard but brittler... no vooddo science here.

Keith Montgomery · Oct 2, 2005

hardheart said:
why harden above 60 on a knife, or use a steel that needs to be hardened to that level for edge retention?

I'm not sure of this, but my guess would be that at 60 HRC ZDP-189 would not show any advantages over a steel such as S30V at the same value. The fact that ZDP-189 can be hardened to 67.5 HRC and still be usable as a blade steel is its advantage. Other blade steels hardened to this value would either chip or fracture very easily or be next to impossible to sharpen.

Once again, I am only postulating, since I have not seen enough information on how ZDP-189 compares to other steels to know for sure if my suppositions are true.

klattman · Oct 2, 2005

Artfully Martial said:
So this would imply that our particular ZDP is somewhat more brittle than another premium SS at the moment?

Only AT THOSE hardness levels. If you run the ATS34 harder or the ZDP softer you may get different results.

So, it's not so easy to make a blanket statement about that. The only way you can say one steel is tougher than the other is to compare them at the same hardness.

Now, since ZDP is usually (so far) run much harder than ATS34 (and if that's the only way you can get it), then the comparison holds for any practucal purposes. BUT, Spyderco says 64 or so.. how much difference does it make? Well, we don't really know.

Habeas Corpus · Oct 2, 2005

klattman said:
The only way you can say one steel is tougher than the other is to compare them at the same hardness.

Now, since ZDP is usually (so far) run much harder than ATS34 (and if that's the only way you can get it), then the comparison holds for any practucal purposes. BUT, Spyderco says 64 or so.. how much difference does it make?

Yep. That's the real question - what's the toughness of ZDP-189 at 64HRC?

Hans

robertmegar · Oct 2, 2005

So far, I have not seen info at that 64Rc hardness. Apparently Hitachi intended ( at least initially) to have ZDP189 hardened to the higher limits.

klattman · Oct 2, 2005

Habeas Corpus said:
Yep. That's the real question - what's the toughness of ZDP-189 at 64HRC?

Hans

Or even at 60, then we could compare it to ATS34 and we could guess (though it's probably not linear) in between.

Actually, It would be neat to see curves of toughness vs. hardness for stainless cutlery steels.

Artfully Martial · Oct 2, 2005

So why isn't Cliff beating the hell out of one of these ZDP knives so we don't have to guess?

WYK · Oct 2, 2005

Artfully Martial said:
So this would imply that our particular ZDP is somewhat more brittle than another premium SS at the moment?

Hrm. 8 on the Charpy scale at 67HRC VS 22+ for ATS34 at 60HRC. That would be almost 3X more brittle, or likely to break or crack or chip. It's unlikely you'll find it matching ATS34's toughness at 64 HRC, either. Is Spyderco laminating it? I hope so. Have fun sharpening it if it isn't.

ZDP 189 is basically the M2 of the stainless world - only it's nowhere near as tough, strong, or easy to sharpen...er...OK, so it's not M2. Maybe it's D2? Nahh D2 is still tougher and easier to sharpen even at 62 HRC. So what is it? Well, it seems so long as they laminate it and keep the core at 67HRC as William Henry does, it may be a fine stainless steel. Worth the price? Shrug.

WYK

Artfully Martial · Oct 2, 2005

I love my D2 stuff.

WYK · Oct 2, 2005

klattman said:
Or even at 60, then we could compare it to ATS34 and we could guess (though it's probably not linear) in between.

Actually, It would be neat to see curves of toughness vs. hardness for stainless cutlery steels.

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.

Does anyone have a good chart of ZDP? I only see the one on AG Russels page. It's hard to believe it only has Carbon and Chormium as it's alloying elements.

WYK

Keith Montgomery · Oct 2, 2005

WYK said:
Does anyone have a good chart of ZDP? I only see the one on AG Russels page. It's hard to believe it only has Carbon and Chormium as it's alloying elements.

There are likely more elements in ZDP-189, but Hitachi has been very secretive about the chemical makeup of this steel.