Knife recommendation. A bit odd one ...

A friend of mine wants to buy a new chefs knife. I asked him if I can help with recommendations ... as you know, that's what we crazy folks like to do.

Here are his requirements:

Wa handle
three layered steel
AT LEAST 67 Rockwell hard

He won't fill out the questionnaire, for him it's all about the HRC. Maybe I am missing something and maybe I have no clue, but I can't remember having one or regularly seeing a kitchen knife THAT hard. Most of my knives are in the 61-65 range and 67 to me sounds like that thing would just be a little bit too brittle.

But I am happy to be educated

sukenari ZDP-189 is pretty much the only knife that I know that goes that hard. On James' site they are stated as 65-67.
I think Takamura have a range around 65.
Others dhould be able to help.

Curious as to why he is looking for HRC 67? Also assuming Three Layered Steel means sanmai construction of some sort?

But the only thing that really comes to mind in that hardness range is ZDP-189. The Sukenari ZDP-189 line is quoted at 66-67 HRC other option would be a Miyabi 7000MCD at HRC66, which I believe zknives says is also ZDP-189. Both of these lines are clad in stainless/nickel damascus.

Just thought of another option actually which is Cowry-X. Hattori makes kitchen knives in Cowry-X I believe also in the 65-67 HRC range.

And also any knives in MC66 such as the Zwillings Cermax line (though this line is not damascus or sanmai I believe)

Many knives in HAP40 steel are claimed to be in the region of 67 hrc

mikedtran said:

Curious as to why he is looking for HRC 67? Also assuming Three Layered Steel means sanmai construction of some sort?

Click to expand...

Yes ... I only came up with ZDP-189 as well.

I am not quite sure why he insists on a HRC that high. I mean, some people want extremes and maybe he thinks the higher the better, but I have no clue. I am not sure how educated he is about knives and steels.

He mentioned that he saw and used a 67HRC (actually it's listed at 66) from Finnish maker Roselli, it's what Roselli calls Ultra High Carbon (UHC) steel, but it's a mono blade ...

What kind of daily maintenance and sharpening strategy does your friend have in mind?

Benuser said:

What kind of daily maintenance and sharpening strategy does your friend have in mind?

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beats me, to be honest. I read here that ZDP189 isn't that easy to sharpen, so I am not sure that's the way to go for someone who might be a novice to sharpening.

I'm not sure I agree with that whole 67HRC focus anyway, because what's the point? I think there are fantastic knives out there at 63HRC or something like that. But maybe he wants a Unicorn, he hasn't told me ...

Wa-handle, san mai, but only hrc 65:66
http://www.japanesechef.com.au/gihei.html

White steel should harden to that and more, file steel is essentially the same and those come in around 70RC. So there you have san mai stock available. Find a custom maker who will get a laugh out of making a 67RC knife. And so long as your friends sharpens it to about 60deg inclusive he shouldn't have much trouble with chipping.

Actually, don't some makers "claim" 65-66RC for their white?



Rick

According to the site, the fujiyama blue #1 line from Tosho should be 66RC.
https://toshoknifearts.com/shop/kni...uchi-tsuchime-gyuto-210-mm-rosewood-octagonal

Sukenari or gihei, fujiwara, japanese chef knives has a few at 65-67 ish. There are tons of options out there in the 65 range, sukenari does make a san-mai 3 layer knife out of zdp-189, its listed as 65+ so it may be worth a gander, the other option as mentioned is custom, seems silly though, it will chip, if knives could be made like this people would be doing it.

fyi JCK just put up a new fu rin ka zan zdp-189 manufactured by sukenari company of toyama very reasonably priced. Not sure koki has specified the HRC but he's always glad to answer emails about such technical questions.

Does your friend subscribe to the notion (for better or worse) that if a knife has a higher HRC, it follows that it is superior? I remember reading a post/thread from Jon at JKI about where sometimes "less is more". Monosteel carbons (~60hrc) have their place too. As a friend id be concerned about recommending such a knife without having some more info

Ceramic blade? :laugh:

Ken's "Black Steel" was tested at 99 HRC. They tried to verify with a second reading and it broke the tester...:groucho:

^^^^^ Ha Ha!

Kiya most hardness! Sharpness long-lasting! Using a high-performance powder high-speed steel · HAP series of Hitachi Metals, Ltd., is the excellent sharpness of Western kitchen knife with high hardness. Metal hardness index HRC (Rockwell hardness C scale) 69 or more more than 68 of the upper limit. Kiya we are proud of the highest hardness in the metal kitchen knife that sells. It is recommended as a household kitchen knife less able to hone. Super P.H. Steel 69-powder steel

That is the Hitachi HAP72, iirc only Kiya has something made of that steel.

HAP72 does not look at all favorable for kitchen knives that would have acute angles and see any board contact.
http://www.hitachimetals.com/product/specialtysteel/toolsteel/doc/YSS_cold_working_die.pdf



Rick

Thanks for the document, Rick, but what brings you to that conclusion about angles and board contact?

Look at the second chart. Also consider that this steel is going to be very similar to s110v in that it is very high in carbide content. s110v is best hardened to 62rc as Phil Wilson recomends, HAP72 a whopping 69, and you would think more prone to chipping. Because of the high carbide content s110v suffers in edge stability, and recommended sharpening is at 30deg+ inclusive, I'd have to suppose similar would apply to HAP72.


Rick

Thanks Rick. IIRC, size and distribution of carbides are far more important than number when edge stability is concerned. And with PM steels both are well controlled. But I'm no metallurgist. As about the sharpening angle, a relatively obtuse angle can lead to a very sharp edge, at least with not too coarsely grained stuff. Some of my best performers have microbevels far exceeding the 30 degree inclusive you mentioned. If the blade is thin enough behind the edge, angles don't matter that much, at least for general purpose in Western cuisine.

On the second chart it shows HAP40 with an A rating for toughness, HAP72 is a C. I don't know about HAP72, but s110v has extremely fine carbides, finer than white steel even. But the greater the carbide numbers the more rigid and brittle the matrix holding everything together becomes. HAP72 may respond well to microbevel in general, though likely be limited in how thin at the edge, but like yourself I've never experienced any of these super wear resistant alloys.


Rick