# HAP40 VS ZDP-189



## DerSnap (Oct 14, 2013)

What is the difference between these two steels? I can see enough information on the ZDP, but even checking Zknives I could not find how it compares to HAP40.

Anyone?

cheers,
Shamus


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## TB_London (Oct 14, 2013)

ZDP features in hitachi's cutlery steels

http://www.hitachi-metals.co.jp/pdf/cat/hy-b10-d.pdf

And HAP40 appears in their cold working tool steels, so harder to compare
http://www.hitachimetals.com/product/specialtysteel/toolsteel/doc/YSS_cold_working_die.pdf

full zdp spec sheet
http://www.discipleofdesign.com/knives/ZDP189_eng.pdf


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## DerSnap (Oct 14, 2013)

Interesting. 
Looking at the hardness it seems they can get pretty similar. I did notice a HAP72 that can hit a 72.
I am more curious though in real life if anyone has compared similar knives with the two steels?


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## TB_London (Oct 14, 2013)

The grind and profile is going to cause more variance than the steel, so unless they were virtually identical except for steel it's be hard to compare (which is part of why the spyderco mules are interesting)

Much better to pick a knife based upon it being a shape and grind that suits you, than take a punt on the latest and greatest steels IMO. 

Saying that i would be tempted by the kono in ZDP


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## DerSnap (Oct 14, 2013)

I agree the knife is more important than the steel. No questions there  Still just curious as I see these metals popping up now of days.


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## TB_London (Oct 14, 2013)

Hap40 has been available for a while from dieter Schmidt
http://www.fine-tools.com/messerp.htm

Only in small sizes though


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## DerSnap (Oct 14, 2013)

Ya I saw Dieter had them and sort of what got my interest. Maybe if there was an Usuba I could go for a smaller size, but not gyuto.
That was also the thing that sort of bugged me about my 7000MCD in that it was 200mm only. I like 240 but ideally I prefer a 260 if possible.

Still metals and alloys I find interesting. It is especially interesting on bikes, which I ride a lot.
I just put a new stem on my MTB and it has 7075 alloy and man is it hard. At least compared to what normally is built. My hubs Chris Kings are also I think 2026 or something, and although works of art in machining they are different. The stem you feel over softer alloys, but technique is also just as important.


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## Knifefan (Oct 15, 2013)

HAP40 and ZDP189 are not really comparable. The only thing they have in common is that they are from Hitachi and that they can reach similar hardness. The chemical composition is:
ZDP189 C 3% Cr 20% Mo 1.3% W 1.5%
HAP40 C 1.3% Cr 4% Mo 5% V 3% Co 8% W 6%
HAP40 is a highly alloyed tool steel, not stainless. ZDP189 was developed as knife steel. Of course you can make a knife from every steel, but given proper heat treatment, ZDP189 should definitely perform better: smaller carbides, easier to sharpen, superior rust resistance.

Have no direct experience with HAP40, but once tried a Kiya knife made of HAP72, hardened to HRC 69. Didn't like it at all. A pain to sharpen, prone to chipping and reactive like Carbon. No match for a Cermax.


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## DerSnap (Oct 15, 2013)

I tried many years back one of the KD series knives off one Chef I worked with. Thing was simply a work of art in every respect. Hard, I think he said a bit tuff to sharpen, sharper than I could imagine or even come close to seeing on any other knife, and as expensive as all hell.

Sure its not just the steel, but all things equal it can be factor. 

HRC69 is pretty darn hard !


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