Hardest heat treats in the game

[Blumbo]

I’ve been polishing a lot recently and have been thinking about how hard it has been to get scratches off hard core steel, even with diamond pastes. Msicard Honyaki and Tanaka AS come to mind. These knives also do strike a balance somehow with edge retention, feeling great on stones and not feeling chippy. I know TF is famous for HT, but what other makers push the limits of hardness without compromising toughness functionally?

 

[jedy617]

A lot of the wear resistant feeling is also the particular steel you are working with, so depends on that too probably

 

[jacobwilder5]

Birgersson is up there. Not sure what he’s pushing on hrc but feels hard and crisp on stones and tough in use. Lovely stuff

 

[MarcelNL]

based on the few samples I have I'd expect Markin to be there too, as well as Hinoura

 

[jedy617]

Yeah markin 67 hrc rex121

 

[MarcelNL]

I have a petty in S380 HRC 67, that just skates off most of my stones, no chips whatsoever and it keeps an edge for months in home use where it sees daily use

 

[NickMinton]

The togashi blue winter honyaki series that several of us got has only been usable on diamond stones…

 

[esoo]

Yeah markin 67 hrc rex121

Doesn't @Deadboxhero push it further than that?

 

[jedy617]

Doesn't @Deadboxhero push it further than that?

Yeah usually around 71 iirc. Andrei says he runs it a bit softer for some durability in the kitchen. Can't imagine what 71hrc is like, I mean my thin ground petty lasted 2 years before needing a touch up

 

[Barmoley]

Yeah usually around 71 iirc. Andrei says he runs it a bit softer for some durability in the kitchen. Can't imagine what 71hrc is like, I mean my thin ground petty lasted 2 years before needing a touch up

Andrei doesn’t heat treat himself, or at least he used to not, he gets these heat treated. He might specify what he wants though. The hardest steel knives I have are Vancron ~69 HRC from Troopah Knives and ASP-2053 ~68.5 HRC from Blank Blades. Both sharpen very nicely on diamond stones and hold an edge very well for me, no chipping issues either.

 

[Bico Doce]

Recent Birgersson drop of blue 1 @ 68 hrc. Already used it a few times, feels great on the board and no micro chipping. Ed Thompson sharpened it before sending it to me to get a feel for the steel on stones. He described it as hard but not glassy and easy to deburr.

 

[MSicardCutlery]

I’ve been polishing a lot recently and have been thinking about how hard it has been to get scratches off hard core steel, even with diamond pastes. Msicard Honyaki and Tanaka AS

Part of it can be the alloy itself, less the hardness. Anything at 65hrc is pretty tough to abrade, but once you add enough tungsten to a steel to produce even a seemingly meager volume of carbides things get worse in a hurry. And the bigger, the meaner. Part of what makes MagnaCut and even Apex Ultra great to grind relative to their edge retention is their even distribution of fine carbides. Wolfram Special has a lower volume of Wc than AU does, but I'd guess that it's at least 25% harder on belts, and at a lower hardness. Reason being the carbide size. Forged it mellows out a great deal. As received it takes roughly twice the belts of 52100 or AEB-L for an equivalently sized blade, which is about the same as CPM-D2 or MagnaCut.

52100 can be taken to 67/68 hrc, 26c3 to about 67hrc, this is after tempering of course. At some point I'd like to make some knives that hard with those steels, but I haven't gotten around to it yet.

 

[dehory]

Recent Birgersson drop of blue 1 @ 68 hrc. Already used it a few times, feels great on the board and no micro chipping. Ed Thompson sharpened it before sending it to me to get a feel for the steel on stones. He described it as hard but not glassy and easy to deburr.

Any notable/noticeable differences between the blue 1 and his usual core steel?

 

[Bico Doce]

Any notable/noticeable differences between the blue 1 and his usual core steel?

That's a great question. I will have to do side by side but nothing that was distinguishably noticeable for me at this point

 

[Just a DK]

They're all in roughly the same range, i tested all 3 tonight.

This is the gyuto i believe.
View attachment 298799View attachment 298800

The gyuto were testing in the 68-68.5 range, the honesuki tested in the 67.5-68 range. And that could have even just been error from flatness or surface finish, since i heat treated them all the same.

But nah, the geometry should make up for the high hrc, since, while it wont be thick directly at the edge because of how honesuki's are ground they tend to get thicker, sooner than a gyuto or other multipurpose knives. Also, i think it should still be in the same range of toughness (if not better, but this is not me saying that it will for sure be) as any of the commonly used japanese steels anyway.

As far as why theyre ground asymmetrical, I do think a big reason comes down to tradition, and because many japanese knife makers already do a lot of single bevel blades.

But i do think it can be useful, having a nearly flat side to kind of register against something while you cut.

Not sure if I will go symmetrical or not for this honesuki. I was thinking of going right biased. But idk.

 

[jedy617]

Part of it can be the alloy itself, less the hardness. Anything at 65hrc is pretty tough to abrade, but once you add enough tungsten to a steel to produce even a seemingly meager volume of carbides things get worse in a hurry. And the bigger, the meaner. Part of what makes MagnaCut and even Apex Ultra great to grind relative to their edge retention is their even distribution of fine carbides. Wolfram Special has a lower volume of Wc than AU does, but I'd guess that it's at least 25% harder on belts, and at a lower hardness. Reason being the carbide size. Forged it mellows out a great deal. As received it takes roughly twice the belts of 52100 or AEB-L for an equivalently sized blade, which is about the same as CPM-D2 or MagnaCut.

52100 can be taken to 67/68 hrc, 26c3 to about 67hrc, this is after tempering of course. At some point I'd like to make some knives that hard with those steels, but I haven't gotten around to it yet.

I hear custom makers always complain that magnacut is always such a huge pain to finish/hand satin even compared to stuff with higher carbide volumes, any truth to that in your experience?

 

[MSicardCutlery]

I hear custom makers always complain that magnacut is always such a huge pain to finish/hand satin even compared to stuff with higher carbide volumes, any truth to that in your experience?

Yep. It sucks. It rough grinds more easily than many other CPM steels, notably ZW, 3V, 154CM, and M4, it feels about on par with D2. When it comes to finishing though...eesh. It'll kill a scotchbrite belt in just 2 or 3 blades, which is about like M4. The same belt will easily last 6-10 blades in carbon steel or AEB type stainless. I'm not sure about other CPM steels since I tend not to make batches of those, but suffice it to say I can use a scotchbrite belt that's too dead for MC on D2 or 154CM no problem. Hand finishing is not fun either. Recently I made a few hand finished CPM blades and both MagnaCut and M4 took the same amount of diamond lapping film to finish. The ZW took only about 70%-80% as much. Now some of that may be due to those steels being hard to abrade with finishing belts and consequently I may have left myself some 120 grit scratches that should have been wiped by the 180 grit belt, but that has been my experience. I do not miss the days of handsanding MagnaCut with Rhynowet.

 

[Barmoley]

This probably has to do with portion of MC carbides vs softer carbides. MC is very fine grained with small carbides, but the higher in grid you go the harder it is to deal with very hard well distributed carbides. MC is probably very close to 4V at higher grids, possibly a bit harder to deal with. You would imagine that ZW is easier at higher grids.

 

[Blumbo]

As a general rule,

Big carbides - harder to abrade, more wear resistant more aggressive edge?

Fine carbides - easier to abrade, less wear resistant and aggression?

outside of sharpening, what other benefits does a fine grain structure provide? Is it tougher/less easy go chip?

And how does hardness interact with these two concepts?

 

[Cliff]

Sukenari HAP40 is up there

 

[jedy617]

This probably has to do with portion of MC carbides vs softer carbides. MC is very fine grained with small carbides, but the higher in grid you go the harder it is to deal with very hard well distributed carbides. MC is probably very close to 4V at higher grids, possibly a bit harder to deal with. You would imagine that ZW is easier at higher grids.

Yes but I've heard from many custom folder makers who say m390 is much easier to finish, which is odd. Pretty sure m390 has more mc carbides no?

 

[jedy617]

As a general rule,

Big carbides - harder to abrade, more wear resistant more aggressive edge?

Fine carbides - easier to abrade, less wear resistant and aggression?

outside of sharpening, what other benefits does a fine grain structure provide? Is it tougher/less easy go chip?

Finer grain structure usually tends to be tougher yeah. Big carbides are usually chippy. And on abrading, pretty sure it's type of carbide, like mc (the hardest ones, like vanadium carbide)

 

[MSicardCutlery]

This probably has to do with portion of MC carbides vs softer carbides. MC is very fine grained with small carbides, but the higher in grid you go the harder it is to deal with very hard well distributed carbides.

This is precisely why.

As a general rule,

Big carbides - harder to abrade, more wear resistant more aggressive edge?

Fine carbides - easier to abrade, less wear resistant and aggression?

outside of sharpening, what other benefits does a fine grain structure provide? Is it tougher/less easy go chip?

A, yes, yes, maybe.

B, yes, yes, maybe

C, yes.

BUT.....

Higher overall wear resistance does not translate to edge retention. Conventional ingot D2 has greater wear resistance than S90V, but S90V makes a far longer wearing edge.

Yes but I've heard from many custom folder makers who say m390 is much easier to finish, which is odd. Pretty sure m390 has more mc carbides no?

Nope. Mostly CrVC which are only a little harder than CrC IIRC

https://i1.wp.com/knifesteelnerds.c...2019/07/steel-carbide-volumes.jpg?w=527&ssl=1

204P/20CV are essentially M390

 

[Barmoley]

As a general rule,

Big carbides - harder to abrade, more wear resistant more aggressive edge?

Fine carbides - easier to abrade, less wear resistant and aggression?

outside of sharpening, what other benefits does a fine grain structure provide? Is it tougher/less easy go chip?

And how does hardness interact with these two concepts?

Tougher. Wear resistance is technically same, but harder to finish at higher grids. Low grid doesn’t seem to matter much. Toughness can be much higher though. Compare d2 to cpm d2. Small well distributed carbides are better.

 

[Blank Blades.]

Larger carbides doesn't mean higher wear resistance. At least not in terms that translate to edge holding.

It will be harder to grind and polish but not really give any benefits to you in use, and reduce toughness by a lot.

 

[aporigine]

I cannot speak to the numbers, but two steels in my care that feel quite hard and crisp (but have not chipped) and hold their edge admirably are:

- Tanaka AS
- I. Doi blue 2 (both regular and his Homura line)

 

[shobudonnie]

Anyone know how hard bill burke treats 52100?

 

[Alder26]

Raquin treats very pure steels to what feels like very high hardness!

 

[plantgainz]

Nihei and masashi sld are pretty hard

 

[WCV]

Anyone know how hard bill burke treats 52100?

Bill used to be active here. The threads below suggest he was previously hitting between 61-63 HRC. Not sure if he has changed anything more recently, but this seems to match with my gyuto from him that is less than 2 years old as best I can tell from use and sharpening. It’s a joy on the stones, feels crisp and deburrs easily. Overall, in use, it feels like he is shooting more for balance with some toughness, rather than the highest hardness. Whatever the HRC, it’s very good in use.


https://www.kitchenknifeforums.com/threads/preferred-rc-hardness.1945/

https://www.kitchenknifeforums.com/threads/bill-burke-300-suji-dragons-breath-damascus.6742/