sharpness capability contest zdp189 vs shiro 2,1 vs aogami 2 vs any other steel you think

[ramtin tashakkor]

hi guys, this is just for fun. assuming they all made with perfect heat treating and care, what steel has the capability to be sharpest of them all? my guess would be with a good set of stones its going to either zdp 189 or white 2. thoughts?

 

[Nemo]

If one defines sharpness as "the ability to hold an acute edge angle", then simple high carbon steels such as white paper steels and 1095 fit this bill (assuming a good heat treatment).

Once you start adding alloying elements to steel, it tends to form carbides (hard molecules of the alloying element and carbon) which are embedded in the steel. Many carbides are large (on the microscopic scale, anyway). Sharpening these steels at an acute edge angle will tend to pull these carbides out, causing the edge to collapse. The more carbides (ZDP189 has a lot), the more obtuse an edge is reqired to maintain edge stability. This is especially so if the carbides are large.

So as a general principle, simple steels will get sharper than highly alloyed steels, provided they have the hardness to support that fine edge (even if they are not nearly as abrasion resistant).

 

[madelinez]

Yeah ZDP-189 is towards the other end of the spectrum. Simple carbon steels or even some stainless like AEB-L get much sharper... and lose that sharpness much faster.

 

[ramtin tashakkor]

If one defines sharpness as "the ability to hold an acute edge angle", then simple high carbon steels such as white paper steels and 1095 fit this bill (assuming a good heat treatment).

Once you start adding alloying elements to steel, it tends to form carbides (hard molecules of the alloying element and carbon) which are embedded in the steel. Many carbides are large (on the microscopic scale, anyway). Sharpening these steels at an acute edge angle will tend to pull these carbides out, causing the edge to collapse. The more carbides (ZDP189 has a lot), the more obtuse an edge is reqired to maintain edge stability. This is especially so if the carbides are large.

So as a general principle, simple steels will get sharper than highly alloyed steels, provided they have the hardness to support that fine edge (even if they are not nearly as abrasion resistant).

great explainatoon sir, thanks

 

[Nemo]

great explainatoon sir, thanks

No problem.

 

[PalmRoyale]

Shirogami #1 gets the sharpest in my experience if the blacksmith has a lot of experience forging it.

Simple carbon steels or even some stainless like AEB-L get much sharper... and lose that sharpness much faster.

That depends on the application. I have shirogami #1 chisels, 66HRc, heat treated to perfection and I can chop with them almost all day long. Not soft wood mind you but the harder kind like Oak and Cherry.

 

[Kippington]

Probably high-hardness Shirogami #3, 1086 or some other eutectoid carbon-steel. No carbides (other than tempering) and smooth as silk...

 

[banjo1071]

Money money is on 145SC or 1.2562

These are crazy steels!

 

[Barmoley]

They are also very different, one is high carbon "simple" carbon with no alloying elements to speak of and the other is still low alloy technically, but high alloy in comparison. What Kip said above makes sense, steel with enough carbon to get very hard, but no more than that.

 

[LucasFur]

This just seems like a fun topic for people.
Sharpness Capability -- meaning how sharp can it get?
I've got AS/Blue1/Blue2/white2/white1/R2 to comfortably shave my face. I'm sure ZDP sharpened properly will also shave.

If you're new to sharpening and don't have a large stone range stick to a white to be able to reach that level relatively easily.

Best edge retention to edge taking to sharpening is a toss up between Blue super(AS) and R2 depending on how much acidic foods you cut up typically.

 

[ThaFurnace]

I'll second (and third) Shiro 3 and AS. I sharpened a ZDP189/66 rockwell paring knife last week. It was my first time sharpening it, and it was a major PITA to raise a burr. Not fun.

 

[inferno]

i think an eutectoid steel will end up on top too.
aka 1086 or 84 or whatever there is. (but these are usually made by **** mills in ****** quality so reality vs theory might not be beneficial for the end user)
the actual process and purity of the steel is important here. and i dont see crucible/carpenter/latrobe/uddeholm/sandvik making any vim/var versions of this if you know what i'm saying..

runner up would be a supersatured no or low alloyed carbon. 1%+C like 1095

runner up after that would be low alloyed carbon like blue 1/2, 52100 and similar (if made well, there is super duper quality 52100 supposedly).

runer up after that is the lowest alloyed pure stainless. like sandvik grades 12c27 12c27m 13c26 any then on up until like 0,8-9 or so carbon content.

these are the fine grained ones!
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then we have tool steels. almost all tool steels.

then we have HSS and SS HSS and high carbon (1% and up) SS in general.

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With hat being said. i feel blue 2 for instance, and also, but to a slighty lesser degree blue super can benefit from an 8k edge. and seriously how much sharper do you need?

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most straight razors are made out of super simple carbon steels like c135 and 52100, and 1095. THERE is a reason for this. And they knew this goddamn well 100 years ago. back in those days it was trial and error but now we have science but its still the same conclusions. they were right back then. otherwise they would have used other steels, simple as that.

a straight razor is usually finsihed at between 8k to 20k. a typical coticule is 8k (and i cant shave off one at all, and i have several).

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but just because you can make a good razor out of steel x doesn't really mean much because it will have other aspects that are not very beneficial to a knife edge, such as rust resistance for instance, toughness and so on.

I have a skd11 (aka d2) blade that gets so sharp it should be illegal. go figure. since d2 is one of the coarsest of all tool steels almost as bad on paper as 440C (pretty much the worst of them all), but yet it gets much much sharper than any of my real stainless knives like r2 and aus8/6. just as sharp as my blue 2 knives too.

maybe it simply doesn't mean that much after all. who knows? i dont but i don know if i can get a 12k edge on a blade and it feels like one of my razors then its good (and i have iwasaki razors btw).

spyderco UF is a good stone for this btw. mirror mirror on the wall! (all of them are warped from the factory though, and you will plow trough several dmt's to flatten them, you are hereby warned, i estimate my UF to 20k)

 

[Knife2meatu]

[...]

... you will plow trough several dmt's to flatten them, you are hereby warned, i estimate my UF to 20k)

It would be very interesting to hear about the durability of the Dia-Flat if it is used to flatten Spyderco ceramic stones.

 

[inferno]

I have not made any efforts to flatten my UF. I simply use the concave side. BUT...
I took a white sharpmaker rod (same material) to knock off all the stray particles off the surface of the UF. and it had about 100 or so. These absolutely has to be knocked off the stone for it to perform. and steel will not knock these off. trust me.

this stone also has to be used dry. if wet it does not work.

Also the stone seems to have dulled/rounded off sharpening elements as opposed to regular japanese waterstones where you try to expose sharp new particles all the time.

it also loads up. so you have to clean it with somethiung, and it will never ever get completely clean. its just how dry stones work.

this stone sharpens like 5% and burnishes 95% and this works very good for the fukn ulitmate sharpness of razors. there is no better stone than this imo. eschers and coticules and jnats can all go F them selves here really . its more polished than a green crox strop (pure crox, no alox inside). you need to put in maybe 1-200 laps though, it takes several minutes. everybody wants the easy way out though so this is not for them. this is true mirror finish. and the stone has no give at all so it takes no prisoners. but yeah its the baddest ass muthat F out there imo. I'd say its twice as fine as my shapton 12k pro. and its cheap. its not a very fast stone tough, its a very slow stone. its a very very fine stone if you do whats needed to it.

I have not tried flattening it with my diaflat plate since i have a feeling the diaflat would lose that battle. its a solid chunk of aluminum oxide. just take off the particles that are sticking up imo and its good. and you can do this with a white sharpmaker rod.

this is maybe your 5-6th stone as a knife enthusisast imo not the second or third. just so you know.

 

[inferno]

yeah

 

[Nemo]

Probably high-hardness Shirogami #3, 1086 or some other eutectoid carbon-steel. No carbides (other than tempering) and smooth as silk...

How much carbon is lost in HT and forging? Is 1095 close to eutectoid by the time the knife is finished or is the C loss negligible?

 

[Kippington]

It depends on the atmosphere in the forge and HT furnace, and how long the knife took to forge, and how hot it was....

It's entirely possible to raise the carbon content of the steel (carburization), given the appropriate circumstances.

 

[DevinT]

High hardness 52100, it has the smallest carbides and the smallest grain of any steel. It is also very clean.

Hoss

 

[madelinez]

High hardness 52100, it has the smallest carbides and the smallest grain of any steel. It is also very clean.

Hoss

I always thought that a clean 52100 with good heat treat had better toughness and stain resistance but worse edge stability compared to Hitachi white steels. That being said I've never tried 52100 and Hitachi white #2 from the same maker.

 

[DevinT]

I always thought that a clean 52100 with good heat treat had better toughness and stain resistance but worse edge stability compared to Hitachi white steels. That being said I've never tried 52100 and Hitachi white #2 from the same maker.

I don’t know how, 52100 is cleaner, has smaller carbides, and has finer grain than white steel. All contribute to edge stability. 52100 can be very tricky to heat treat though.

Hoss

 

[Nemo]

I don’t know how, 52100 is cleaner, has smaller carbides, and has finer grain than white steel. All contribute to edge stability. 52100 can be very tricky to heat treat though.

Hoss

Is it easy to explain what makes 52100 difficult to heat treat?

 

[DevinT]

Is it easy to explain what makes 52100 difficult to heat treat?

Some of it has to do with the fact that the carbides dissolve much slower than those in simple carbon steels. Carbides need to dissolve to put carbon and alloy in solution strengthening the matrix. The Ac3 temperature is higher giving it a narrower heat treating range also. Retained austenite can be a problem for both 52100 and white steel. Normalizing and annealing are also more complicated for 52100, the condition of the steel going in to the quench and temper is very important.

From personal experience, it’s been tricky dialing in the heat treat.

Edit, a well heat treated 52100 blade is amazing.

Hoss

 

[Nemo]

Some of it has to do with the fact that the carbides dissolve much slower than those in simple carbon steels. Carbides need to dissolve to put carbon and alloy in solution strengthening the matrix. The Ac3 temperature is higher giving it a narrower heat treating range also. Retained austenite can be a problem for both 52100 and white steel. Normalizing and annealing are also more complicated for 52100, the condition of the steel going in to the quench and temper is very important.

From personal experience, it’s been tricky dialing in the heat treat.

Hoss

Thanks Hoss. It sounds like there are quite a few ways in which the HT is easier to muck up.