Japanese White Steels vs. 1095?

Maybe Bluntcut won't mind if I show my ignorance too!!!!

Why doesn't O1 meet his critieria? Not enough W or V carbides in O1. Could be more, with more carbon to make them.

The "toothy" edge is 95% based on sharpening grit and technique. Some steels, like D2, do better with a "toothy" edge because they have large carbides in the matrix. Much larger than the steels I would like to have around to play with. I cannot stand D2 at all.

Highly polished, low angle edges, optimal carbide size and distribution......YES!!!

You're probably right, Bluntcut, about all that vanadium in my steel of dreams. 3% is probably WAY to much!!!
 
does know the avg carbide size of o1? I have determined that if the carbide size is below a certain point you'll never notice the difference. And yeah I agree with you too, but I also agree with bluntcut
 
I think D2 is a highly underrated steel for some applications, and has a bad rap with some folks due to industry specifications for heat treating intentionally allowing for considerable quantities of retained austenite, which is detrimental for us knife people in edge stability. With a different approach to heat treat, and some 'unorthodox' processes, I suspect this steel would be a real eye-opener for many.
 
... I just realized my statement regarding D2 wasn't in the context of this thread. I wouldn't suggest it's use in a kitchen knife, as many here have already stated their preference for extremely fine grain and minimal alloy carbides in a kitchen knife. It can, however, make a perfectly good knife for a variety of other purposes, and that was what I was trying to say.

I would agree, however, that geometry and proper heat treatment are the two most important factors, regardless of steel choice. I'd say my own opinion mirrors Darrin Sander's - he summed it up rather nicely, I think.
 
Carbide size is highly variable, particularly in the relatively low alloy steels discussed in this thread. The absolute smallest carbides would be tempering carbides produced during tempering of a steel with no primary carbides, such as 1084, 1075, 1060, 5160, and a host of others with relatively low carbon (<0.8% given small amounts of carbide forming elements). These are extremely fine and are generally too small to see even with optical microscopes.

Most low alloy steels will have carbide sizes smaller than 1 micron, and many will be less than 0.5 mircron. A very sharp edge is roughly the same size at the edge. So, there seems to be a breaking point where the carbides are smaller than the edge radius/thickness.

52100 specifically has carbides in the 0.5 to 0.2 micron range given typical heat treatments. O1, and the various others discussed here will be in the same range or perhaps smaller. Tungsten carbides in particular are known for their small size due to the very low mobility of the large/heavy tungsten atoms. However, the only way to know for sure what size carbides are present are to measure them, which is fairly expensive. It requires mounting, polishing, etching, and someone experienced with a good microscope and some time.

Here is the catch though. Heat treatment of steels like those discussed here is critical in carbide size. Too low a temperature, and they will be bigger than you think. Too high a temperature, and they can be too small or erased all together. So, these sizes aren't fixed, and will vary depending on heat treatment as well as prior processing of the steel from the mill. Unlike Bluntcut, I would group O1 in with those steels. AEB-L, 13C26, 12C27, 420HC, and other similar low alloy, (relatively) low chromium, medium carbon stainless steels have carbides in the size range you're after.

Someone asked in this thread somewhere about various carbide formers. Iron is a carbide former as well. Iron carbide, while softer than tungsten, chromium, or vanadium carbide, is still carbide and has a pretty significant effect on wear in steels. Particularly for a wood working knife, it is much harder than wood, and will help resist wear during cutting. It also has the benefit of being easy to manipulate via heat treatment, requiring lower temperatures and shorter times than the harder and more complex carbides.
 
Oh, a couple things I forgot to mention.

Silicon doesn't generally form carbides in steel, though there can maybe possibly be some silicon/aluminum carbonitrides present from when the liquid steel is deoxydized. Generally, it has better places to be, like dissolved in the matrix, taking the place of iron atoms. What I mean is it doesn't behave like the usual carbide forming elements we normally think of like W, V, Cr, and others.

One other thing. The world of carbides gets very complicated. Without exact specific research and reading, I'd be very hesitant to say anything with 100% certainty. For example, various carbides will dissolve various other elements, thus making things fairly complex. Take 52100. The carbides in this steel (and low alloy steels in general, with some exceptions) are a mixture of chromium carbide (small amount) and iron carbide with chromium dissolved in it (a larger portion).
 
My question as a smith is why are honyaki blades considered to be harder to make and brittle and forge welded kasumi blades easier? The kitchen blades that i have forged out of round bar W2 have been easier to make than the 1084/15N20 ladder damascus ones. Furthermore, Bob Kramer say that his "honyaki" 52100 blades will do stupid blade tricks that he won't guarantee that his damascus blades will do like pass an ABS performance test. ;) The only answer that I can come up with is that the techniques and steel are designed for the rather primitive traditional Japanese bladesmithing techniques. Those guys do stuff like hammering a cold blade that would cause most of us unsophisticated gaijin smiths to have an aneurism if we saw someone doing it. LOL. I wonder why such a high quit steel as the "paper steel" would be brittle at 62-63 Rc when plain old W2 or low temperature austenized 52100 are still pretty tough at those hardness levels, as least as far as hard kitchen knives can be called tough?
 
me2 said:
Oh, a couple things I forgot to mention.

Silicon doesn't generally form carbides in steel, though there can maybe possibly be some silicon/aluminum carbonitrides present from when the liquid steel is deoxydized. Generally, it has better places to be, like dissolved in the matrix, taking the place of iron atoms. What I mean is it doesn't behave like the usual carbide forming elements we normally think of like W, V, Cr, and others.

One other thing. The world of carbides gets very complicated. Without exact specific research and reading, I'd be very hesitant to say anything with 100% certainty. For example, various carbides will dissolve various other elements, thus making things fairly complex. Take 52100. The carbides in this steel (and low alloy steels in general, with some exceptions) are a mixture of chromium carbide (small amount) and iron carbide with chromium dissolved in it (a larger portion).
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Isn't silicon a similar but less effective alloying element than nickel in that can give a bit more toughness to the blade when used in small proportions?
 
Yes, I think it works in a similar fashion. It is known that silicon suppresses the formation of cementite (iron carbide). This increases toughness, and most of the shock tool steels (S series) depend on silicon for the high toughness at relatively high hardness. I've talked with mete about the mechanism for nickel increasing toughness, but even he didn't know what it was and I've not been able to find it either. I think silicon is generally regarded as better when one is strictly after toughness. However, the two act in opposite ways, so other considerations must be taken. For instance, silicon generally raises the austenizing temperature, while nickel will tend to lower it.
 
Great info! Thanks Me2. Did NOT know that about silicon. Carbides in steel, their size, their makeup, distribution, you could get lost for days studying that stuff!
 
jdm61 said:
. LOL. I wonder why such a high quit steel as the "paper steel" would be brittle at 62-63 Rc when plain old W2 or low temperature austenized 52100 are still pretty tough at those hardness levels, as least as far as hard kitchen knives can be called tough?
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not sure. i have made kitchen knives of O1 that were tempered to Rc64 and had no issues with brittleness. i was not batoning or using them on wood or bones, but not no brittleness issues.
as an aside, most wood carving knives and blades, and some planes use O1 at Rc60-63. when properly heat treated, O1 has 9.5 grain size.
scott
 
A while back, I got hold of some old school German 115W8 metal cutting band saw steel. If you look at the specs for it and the Hitachi steels, the 115W8 almost looks like perhaps "Blue #1.5" It has the carbon content of the #2 steel at around 1.15% but a tungsten content equal to that of Blue #1 at around 2%. Having used a bit of the stuff I can tell you with a fair degree of certainty that the 115W8 is as tough as a cheap buffet steak at 62Rc and that has been others experience to. What I was told was 64 Rc for kitchen knves and 62Rc if you want to do something silly like cut nails with it. :D It takes a nasty edge too. I made a D-handled suji out of the stuff that would cut you if you thought about the knife for too long.;) The HT I used was slightly under 1500F, soak for 15-20 , quench in AA type oil and temper at 375F IIRC. That would give me around 63-64. I also made a hunter and a bushcraft knife at 62 and on the hunter quenched in Parks 50 (all I had at the time) and tempered at 400F. .Thant should give me the 62Rc and with that little bushcraft knife which is .140 thick and tapered slightly, I can flex the tip with no ill effect, so not brittle by any stretch of the imagination. So once again, why are these similar Japanese steel considered "brittle" and difficult to work with. I was also reading something recently about certain western steels, either 52100 or AEB-L being less prone to a tough "wire edge" than similar Japanese knife steels. If this is true, I am wondering if that wire edge is an issue of RA due to how they make their knives rather than alloy composition?
 
I have heard quite a bit about 115W8 (1.2442). Achim Wirtz being one knifemaker who really loves that steel. I found a supply for 110WCrV5 (1.2519), and it too is like Blue steel. Not really the same steel as 1.2442, but from I gather, both of these steels are LOVED by whoever uses them. I have only used the 1.2519, and I am HOOKED.

I was not aware of Hitachi steels being "brittle" or "hard to work with" at all. Blue 2 that Aldo has works like a dream. Not sure what they are getting at there.

I had White steel professionally heat treated a couple years ago. I think they used 1575F instead of 1475F. The knife takes a good edge, but it does not last at all. I have a feeling they over heated the steel by 100F degrees. Not sure, but an educated guess due to some other talk about how these people were treating 1095 at the time. With 1575F austenitizing temps! Yikes.
 
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Matthew Gregory said:
... I just realized my statement regarding D2 wasn't in the context of this thread. I wouldn't suggest it's use in a kitchen knife, as many here have already stated their preference for extremely fine grain and minimal alloy carbides in a kitchen knife. It can, however, make a perfectly good knife for a variety of other purposes, and that was what I was trying to say.

I would agree, however, that geometry and proper heat treatment are the two most important factors, regardless of steel choice. I'd say my own opinion mirrors Darrin Sander's - he summed it up rather nicely, I think.
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Matthew,
Just to stir the pot here, I've used CPM-D2 on a large set of culinary that a customer asked for some stain resist, but not a real stainless which after discussing that with him I explained in knife maker lingo that a true stainless was about 12% chromium or higher.

The CPM-D2 was a prefect compromise of what he wanted and what is real in the world. I've had the set back for sharpening several times over the years and they have great edge retention, no tearing or chunky looking edge at a 10x mag, and just enough corrosion resist. The the health dept won't scream CARBON STEEL! If they see these knives at his work.
 
I've got very little experience with D2, but I suspect people's reaction to it is much akin to 440C. Done wrong, no one likes that, either, but the same folks would likely be amazed when it's done right.

CPM-D2 is to D2 what CTS-XHP is to 440C...


Joe, be careful. Your questions are starting to smack of heresy... ;)
 
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samuraistuart said:
I was not aware of Hitachi steels being "brittle" or "hard to work with" at all. Blue 2 that Aldo has works like a dream. Not sure what they are getting at there.
.
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Likewise. Most of my knives are Hitachi paper steels which have been forged properly with no issues. Sounds like somebody is starting negative hype. . . Jay Fisher comes to mind (who makes the ugliest, least functional knives I have ever seen).
 
Fritz MacKrieg said:
Likewise. Most of my knives are Hitachi paper steels which have been forged properly with no issues. Sounds like somebody is starting negative hype. . . Jay Fisher comes to mind (who makes the ugliest, least functional knives I have ever seen).
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Fritz, we are stating the "conventional wisdom" about Japanese knives. That is why I wonder if the problem may be the Japanese insistence on using traditional methods including quenching some steels in water that might do better in say Parks 50 or even AAA or austenizing in the forge?
 
D2 can be done well. For culinary it's doable, maybe perfect if you're into custom patinas, cause it does that nice.
crrJYtQl.png
 
B34NS said:
D2 can be done well. For culinary it's doable, maybe perfect if you're into custom patinas, cause it does that nice.
crrJYtQl.png
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The strike against D2 for hign end kitchen knife use may be that even when done the Dozier way, it is not going to support that super fine edge like 52100, AEB-L/13C26, W2, the Hitachi steels, 115W8, etc., RWL 34, CPM 154 (to a lesser extent) or even weird harder to work with stuff like CPM 3V or CPM M4. I noticed that after using CPM 154 and later, CTS-XHP, Joel from Cut Brooklyn has now switched over to AEB-L for his stainless knives and 52100 and 1095 for the carbon models. Now why he is charging 75% more for 52100 than 1095 and even why he is using 1095 for his lower priced blades I can't tell you, but there it is. Aldo's 52100 only costs about 5-6% more than his 1095.
 
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