Monosteel Blade Confusion

[musicman980]

I'm a little confused on monosteel blades. I hear monosteel hitachi steels are too fragile and need to be honyaki to be usable. I also see other knives that are monosteel carbon knives and are not honyaki. So first, why do mono hitachi carbon steels need the honyaki treatment and others do not, and second, can a monosteel AEB-L 5mm thick mioroshi deba be possible without softening the spine?

 

[RDalman]

monosteel whichever Can be made just fine without honyaki process, without softening spine too. IF heat treated and tempered properly (not just a forge flash temper, that style of making might warrant honyaki process yes). I mean a "modern" accurate heat treat, with a tested formula.
Aeb-l doesn't exist in 5 mm. but i think 13c26 does, and it would work well for that purpose I think

 

[HRC_64]

...a monosteel AEB-L 5mm thick mioroshi deba be possible without softening the spine?

Suisin Inox Honyaki, which I believe a variant of 19c27 @ ~61 HRC,
is, despite the name, a uniform-hardness sweedish stainless series.

They make a (pricey) 240mm x miorishi deba, see below link
http://www.korin.com/HSU-IHYMI-240

edit: the suisin alloy corrected for typo

 

[musicman980]

A place near my hometown has AEB-L up to .195" inch thick 4' x 2" billets that I was thinking about turning into a mioroshi. Is the catch that it can't be super high hardness? Removing the heads from fish is a demanding task, but a monosteel non-honyaki carbon or AEB-L could handle it if properly or thoroughly heat treated?

 

[bahamaroot]

...I hear monosteel hitachi steels are too fragile and need to be honyaki to be usable...

Where did you hear this? It's BS.

 

[musicman980]

Isn't one of the benefits of a soft cladding added strength?

 

[musicman980]

Less likely to break

 

[Bensbites]

A place near my hometown has AEB-L up to .195" inch thick 4' x 2" billets that I was thinking about turning into a mioroshi. Is the catch that it can't be super high hardness? Removing the heads from fish is a demanding task, but a monosteel non-honyaki carbon or AEB-L could handle it if properly or thoroughly heat treated?

I have looked into AEB-L a little, I am pretty sure something like 60 HRC from a professional HT service is about where you want to be. The pros might know more and can correct me.

 

[bahamaroot]

Isn't one of the benefits of a soft cladding added strength?

Yes but that doesn't imply that monosteel knives can't be done.

 

[RDalman]

I think suisin uses 13c26 (sandvik)
Aeb-l is made by uddeholm-böhler (here in sweden munkfors, I buy directly from them) and the thickest it's made in is 3,5mm. So if someone is selling it thicker ask to see the certificate or get a copy, my bet is it's 13c26 (not that there's any big differences between them but you should get the right info)

 

[S-Line]

I think suisin uses 13c26 (sandvik)
Aeb-l is made by uddeholm-böhler (here in sweden munkfors, I buy directly from them) and the thickest it's made in is 3,5mm. So if someone is selling it thicker ask to see the certificate or get a copy, my bet is it's 13c26 (not that there's any big differences between them but you should get the right info)

Suisin Inox Honyaki, which I believe a variant of 12c27 @ ~61 HRC,
is, despite the name, a uniform-hardness sweedish stainless series.

They make a (pricey) 240mm x miorishi deba, see below link
http://www.korin.com/HSU-IHYMI-240

I think Suisin is Sandvik 19c27

 

[musicman980]

Yes but that doesn't imply that monosteel knives can't be done.

Oh I'm aware that monosteel knives are made, I was just under the impression that a monosteel non honyaki hitachi steel knife would be a little too brittle for the average user. Does one exist?

 

[musicman980]

I think suisin uses 13c26 (sandvik)
Aeb-l is made by uddeholm-böhler (here in sweden munkfors, I buy directly from them) and the thickest it's made in is 3,5mm. So if someone is selling it thicker ask to see the certificate or get a copy, my bet is it's 13c26 (not that there's any big differences between them but you should get the right info)

Ah thank you for this info, whenever I'm home next I'll have to check that out.

 

[Pensacola Tiger]

Oh I'm aware that monosteel knives are made, I was just under the impression that a monosteel non honyaki hitachi steel knife would be a little too brittle for the average user. Does one exist?

Sure. The Gesshin Ginga from JKI is HRC 61. https://www.japaneseknifeimports.co...products/gesshin-ginga-240mm-white-2-wa-gyuto

 

[Interapid101]

Oh I'm aware that monosteel knives are made, I was just under the impression that a monosteel non honyaki hitachi steel knife would be a little too brittle for the average user. Does one exist?

Masamoto KS also.

A place near my hometown has AEB-L up to .195" inch thick 4' x 2" billets that I was thinking about turning into a mioroshi. Is the catch that it can't be super high hardness? Removing the heads from fish is a demanding task, but a monosteel non-honyaki carbon or AEB-L could handle it if properly or thoroughly heat treated?

I'd like Larrin or another expert to comment, but heat treat can't really be defined as "proper" or "thorough." There are optimized heat treat parameters for a given steel, but whatever protocol is optimal for that given steel will also depend on the target hardness/toughness.

 

[musicman980]

Sure. The Gesshin Ginga from JKI is HRC 61. https://www.japaneseknifeimports.co...products/gesshin-ginga-240mm-white-2-wa-gyuto

Why do most J knife makers do san mai? Is it a cost issue? And does the heat treatment need to be any more precise or finicky to get a monosteel hitachi non honyaki rightly treated?

 

[musicman980]

The benefit of honyaki is added strength right?

 

[Pensacola Tiger]

Why do most J knife makers do san mai? Is it a cost issue? And does the heat treatment need to be any more precise or finicky to get a monosteel hitachi non honyaki rightly treated?

If you want the edge to be HRC 64-65, you either use san mai construction or you differentially harden the blade (honyaki). Considering the failure rate of honyaki blades when they are quenched, most smiths use the technique that produces the highest yield if they are not selling to the high-end market.

 

[Interapid101]

The benefit of honyaki is added strength right?

Strength is not exactly a descriptive term here. Toughness is appropriate. Honyaki knives should have enhanced toughness in the spine and tang. In some cases the honyaki process may also allow a maker to bring the edge to a higher hardness (but likely less toughness) than they would have done otherwise.

 

[Pensacola Tiger]

The benefit of honyaki is added strength right?

No, the benefit of honyaki is a higher HRC edge without compromising the toughness.

 

[musicman980]

No, the benefit of honyaki is a higher HRC edge without compromising the toughness.

Sorry, just for clarification. The benefit of honyaki is not that strength/toughness is added, but that toughness does not go down when heat treating a monosteel blade to high HRC?

 

[musicman980]

Meaning a honyaki 64 HRC is stronger/tougher than a regular monosteel 64 HRC, all other conditions being the same?

 

[HRC_64]

I think Suisin is Sandvik 19c27

Thanks for the correction, I've edited the post above

 

[chinacats]

Where did you hear this? It's BS.

Thank you!

 

[XooMG]

Many of the benefits of laminates are in workability. Forging, grinding, bending, polishing. A lot of user maintenance with simple equipment is easier too. Primary "strength" benefit is in limiting propagation of failures like chipping.

Monosteel works fine.

 

[BloodrootLS]

Sorry, just for clarification. The benefit of honyaki is not that strength/toughness is added, but that toughness does not go down when heat treating a monosteel blade to high HRC?

First of all, strength is not similar to toughness and they can even be inversely related in some situations.

Secondly, honyaki blades are not necessarily tougher/less likely to "break" than monosteel, and actually I would say in general, because of the way they are heat treated and tempered they are often less "functionally" tough than the majority of monosteel blades heat treated at the same high hardness that are heat treated with temperature controlled equipment. Honyaki blades have an area of the spine that is unhardened steel. This would likely stop a crack from propagating if the crack reaches that area of the blade. Of course, if this happens the blade is already completely ruined. Knives break near the edge or at the tip in 99% of the cases and the toughness of the spine rarely matters for the end user (it does matter for the knife maker during manufacture). Carbon steel at HRC 64-65 is quite tough unless heat treated in a way that compromises toughness and at most blade cross-sectional geometries, the toughness of the spine is a moot point. From my understanding the main reason the spine is left unhardened on honyaki blades is A- because it's difficult to do, is traditional, and looks pretty, and B- because it allows some straightening of the blade during manufacture if it warps.

Also, there is another way to toughen the spine of the knife than the "honyaki" approach that make the spine even tougher than the unhardened steel of the honyaki method and also preserves resilience and rigidity. Differential tempering.

Additionally, knives without either kind of softened spine can be excellent top-shelf knives- everything depends on the intended use, geometry, alloy, and heat treatment.

In my mind it is not very productive to oversimplify the effects of the basic knife blade constructions. Great knives can be made all of these ways.

~Luke

 

[BloodrootLS]

Many of the benefits of laminates are in workability. Forging, grinding, bending, polishing. A lot of user maintenance with simple equipment is easier too. Primary "strength" benefit is in limiting propagation of failures like chipping.

Monosteel works fine.

+1

 

[musicman980]

Wow this really clears a lot up, thank you everyone. I just read a bit on the defining terms of knife blade construction, including technically what "toughness" means and so on, I guess I'll have to watch out how I use layman terminology.

So to wrap this up and around to the intent of my original post: Considering the intended use of the blade, is it generally advised to build a deba knife with something other than monosteel construction? Or can it fulfill all of its deba duties if the mono (AEB-L) steel has low hardness and high toughness? I just don't want it to snap and chip, guys, that's all.

I hope that's not another ignorant question.

 

[Kippington]

Here's the thing: 'Chipping' and 'snapping' could be considered two very different modes of failure.

To simplify things, take a look at chipping of this kind:

This happens to be a san-mai blade with tougher steel cladding... but the important thing is this: The chip happened beyond the reach of any tougher steel which could've prevented it from happening.
So it wouldn't make any difference if this was mono-steel, san-mai or honyaki. This chip-out has nothing to do with any of that and only depends on the heat treatment, the bevel angles (or steel thickness near the edge) and the way the knife was used.

On the other hand, the following picture is a totally different thing. Is this what you're worried about?

Both san-mai and honyaki style construction could help prevent this kind of thing from happening, as the cracks would have to propagate through the tougher steel. But there are other reasons this happens too, and a well constructed mono-steel blade shouldn't have this happen either, as others have mentioned above.

 

[Larrin]

Toughness is most likely to be important with kitchen knives in terms of chipping of edges or breaking off tips, neither of which is affected by lamination. The laminated sides are usually softer, or less strong, not stronger. So if you tried to break the entire knife in half it would definitely change its properties there.