ZDP-189 - Overrated or Super Steel?

[Larrin]

I love ZDP. It gets stupid sharp with no real effort, given you use the proper stones and it keeps that sharpness for quite a long time. Overrated ? Compared to what... unobtanium !?

It was rated by its manufacturer as being stainless. It is not stainless, therefore it was overrated.

[Ankerson]

I love ZDP. It gets stupid sharp with no real effort, given you use the proper stones and it keeps that sharpness for quite a long time. Overrated ? Compared to what... unobtanium !?

It was rated by its manufacturer as being stainless. It is not stainless, therefore it was overrated.

I agree. :)

Not sure why they did that though.. :confused:

[The Mastiff]

I think it would be too confusing to try to put out a 20% chrome steel and not call it stainless. It also limits the customer base somewhat. So, technically it is stainless according to the " above 12 % chrome" ( or whatever number is quoted) number used in commercial writings.

It is confusing to explain to average non forum type users why it isn't stainless. Heck, the average magazine writer wouldn't understand the reason and they are "experts". :rolleyes:

Joe

[cbrstar]

When you look at the original Hitachi spec sheet it doesn't state stainless. it just mentions that it has good corrosion resistance. https://www.discipleofdesign.com/knives/ZDP189_eng.pdf So is the "Stainless" simply assumed from the high CR content? Looking back at this thread https://www.bladeforums.com/threads/zdp ... 10.389388/ Larrin didn't see fit to correct anyone claiming that it was stainless at the time.

[Larrin]

When you look at the original Hitachi spec sheet it doesn't state stainless. it just mentions that it has good corrosion resistance. https://www.discipleofdesign.com/knives/ZDP189_eng.pdf So is the "Stainless" simply assumed from the high CR content?

On other pages they call it stainless, and the comparison with ATS34 and 440C implies it as stainless. A couple other pages:
http://www.hitachi-metals-ts.co.jp/prod ... teels.html
https://www.hitachi-metals.co.jp/e/yss/ ... dp189.html

Looking back at this thread https://www.bladeforums.com/threads/zdp ... 10.389388/ Larrin didn't see fit to correct anyone claiming that it was stainless at the time.

1) I didn’t say anything about corrosion resistance there.
2) I hadn’t done any corrosion resistance experiments or estimates of any steels at that time.
3) I change my mind based on new information. That thread was over 13 years ago and now I have analyzed and tested ZDP-189.
4) I was not yet a metallurgist then, because I had graduated high school less than a year before.

[kennethsime]

My first two Spydercos were in ZDP-189, and I loved them. Seemed to hold the fine edge from the factory forever, and sharpened up quick enough.

I never had any issues with corrosion.

[Larrin]

I think it would be too confusing to try to put out a 20% chrome steel and not call it stainless. It also limits the customer base somewhat. So, technically it is stainless according to the " above 12 % chrome" ( or whatever number is quoted) number used in commercial writings.

It is confusing to explain to average non forum type users why it isn't stainless. Heck, the average magazine writer wouldn't understand the reason and they are "experts". :rolleyes:

Joe

I agree the “definition” of stainless steel needs work. The minimum chromium content being given as 10.5, 11, or 12% (depends on where you look) only really works for very low carbon steels. Though people have mostly gotten the memo with 12% Cr D2 being non-stainless. At least among knife enthusiasts.

[Ankerson]

I think it would be too confusing to try to put out a 20% chrome steel and not call it stainless. It also limits the customer base somewhat. So, technically it is stainless according to the " above 12 % chrome" ( or whatever number is quoted) number used in commercial writings.

It is confusing to explain to average non forum type users why it isn't stainless. Heck, the average magazine writer wouldn't understand the reason and they are "experts". :rolleyes:

Joe

Joe,

Yeah your right, and the ave magazine writer is NOT an expert, not really, they are writers.

[Doc Dan]

I love ZDP. It gets stupid sharp with no real effort, given you use the proper stones and it keeps that sharpness for quite a long time. Overrated ? Compared to what... unobtanium !?

Yup, it stays sharp for a long time, longer than any other steel I’ve tried. I find it harder to sharpen, though, for some reason...not as bad as S110V though.

[JD Spydo]

I haven't had any sort of problems with ZDP corrosion wise, but then I know it's not stainless so I treat it as such.

Well Ankerson I'm glad you've had those kinds of good results with ZDP-189 concerning corrosion issues. I've kind of come to the conclusion that my problem might actually be confined to food acids. They are a group of corrosive compounds of a completely separate category I'm finding out the hard way :o .

The variety of tomato I was cutting up that day that wreaked havoc on my ZDP blade was a very high acid variety of tomato. But I've also had other food acids affect some of my cutlery over the years in the kitchen and in the field. I guess I put about 90% of the responsibility on "Your's Truly" because I didn't immediately clean it with fresh water after using. Since then I've been very fastidious and mindful about keeping any cutlery clean after processing any food item.

Very interesting thread.

[Ankerson]

I haven't had any sort of problems with ZDP corrosion wise, but then I know it's not stainless so I treat it as such.

Well Ankerson I'm glad you've had those kinds of good results with ZDP-189 concerning corrosion issues. I've kind of come to the conclusion that my problem might actually be confined to food acids. They are a group of corrosive compounds of a completely separate category I'm finding out the hard way :o .

The variety of tomato I was cutting up that day that wreaked havoc on my ZDP blade was a very high acid variety of tomato. But I've also had other food acids affect some of my cutlery over the years in the kitchen and in the field. I guess I put about 90% of the responsibility on "Your's Truly" because I didn't immediately clean it with fresh water after using. Since then I've been very fastidious and mindful about keeping any cutlery clean after processing any food item.

Very interesting thread.

Yeah...


If you thought it was stainless then it makes perfect since why you didn't clean off the blade right away.

I know I don't clean off stainless blades right away, but non stainless I do rinse them off as I use them.

I treat my stainless knives like red headed step children.... LOL

[sal]

Hi Larrin,

I agree that some of the definitions need adjustment. New steels developed like Powdered and Nitrogen steels do change the field. As always, we appreciate your participation.

FYI, I was deleting some very old emails yesterday and I came across your email saying that you are now living in Golden and would like to know if you can visit Spyderco.

sal

[ZrowsN1s]

There are a few Spyderco Steels I never hesitate to buy, meaning that if I see a design I like, and it has one of those steels, I don't hesitate to pick one up. ZDP-189 is most definitely on the list of steels I don't hesitate to buy.

[Larrin]

FYI, I was deleting some very old emails yesterday and I came across your email saying that you are now living in Golden and would like to know if you can visit Spyderco.

sal

Those are some old emails! Our son was born while we lived in Golden and he is 8 years old now. We liked living in Golden.

[sal]

Yup, time to clean out the old emails. Some I save.

Golden is special.

sal

[Tdog]

ZDP does have some good qualities though IMO overrated. At the time it first came out it might have been considered a "supersteel" but no longer. It gets sticky sharp pretty easily and holds it's edge reasonably well, though the Spydies I have in ZDP tend to be "chippy" and definitely NOT stainless. Around saltwater it rusts quickly. I prefer VG10 to ZDP. I remember when the first Leek's came out with ZDP, I got one and thought it was the cat's meow. Still have a few Leek's, a good design.

[cbrstar]

I watched a video by Cedric and Ada where he put a few knife steels in water including ZDP-189, and I was kinda shocked that it actually appeared to do worse then M4.

I've got two questions about it that hopefully don't sound too silly.

1) I've read about Galvanic corrosion where you can have a stainless steel corrode when it's connected to another steel and in the presence of a electrolyte. So if ZDP-189 is an alloy and seems like they combined high stainless steel with high carbon. Can that create a galvanic reaction within itself if there is an electrolyte?

2) I've also read that some stainless steels need the help through different passivization processes such as cleaning with acids to fully form the passive layer. Is ZDP-189 such a steel? And would polishing it give better results?

[Larrin]

I watched a video by Cedric and Ada where he put a few knife steels in water including ZDP-189, and I was kinda shocked that it actually appeared to do worse then M4.

I've got two questions about it that hopefully don't sound too silly.

1) I've read about Galvanic corrosion where you can have a stainless steel corrode when it's connected to another steel and in the presence of a electrolyte. So if ZDP-189 is an alloy and seems like they combined high stainless steel with high carbon. Can that create a galvanic reaction within itself if there is an electrolyte?

Galvanic corrosion is possible when one steel is more corrosion resistant than another (the less corrosion resistant steel corrodes faster). You would need a corrosion expert to tell you more than that.

2) I've also read that some stainless steels need the help through different passivization processes such as cleaning with acids to fully form the passive layer. Is ZDP-189 such a steel? And would polishing it give better results?

Passivation is not necessary for forming a passive layer. It is intended to remove free iron particles and to promote passivation in the areas where they have been removed. It isn’t common with knives, however.

[40mm]

Jazz (or anyone for that matter!) do you have any pics of your ZDP knives with patinas? I'd love to see what they look like. Thanks man!

I find ZDP just patinas lightly, and looks fantastic. I like the steel, and hope for a ZDP Delica wharnie, and K390, while we're at it. Not being a steel snob, I also like VG10 just fine. Just ask my work knife that cuts tons of cardboard if there's anything wrong with VG10.

[Wdr65]

I’ve carried and used ZDP-189 working outside during the hot, humid summers here in southeastern NC. I’ve had some light speckling and maybe a slight patina. I sweat pretty profusely in the heat and for comparison I treated my super blue endura the same way as my zdp and it has slight pitting.

As far as edge retention, Zdp is one of my favorites. It just keeps going on abrasive material that dull many other steels quickly. I assume it’s the hardness. It was the first super steel I purchased and I could tell the difference between it and Vg-10, s30v and 154cm.