Hello everybody. I want to start a discussion on this topic. Now most of the plain carbon and low alloy steels have an as quenched hardness around 65+. Then they're drawn to toughen up the blade a bit. I rarely see any knife made even with the custom makers with a finished hardness above 61 and most are 59-60. I'm curious why. The Japanese use similar steels and they're left 63+. Now besides purity white no2 is not much different than a good w1 or 1095 and even then we're talking a couple hundredths of a percent. And 52100 is known as a tough still so the hardness should be a blessing to be notched up a few point. I understand factory knives are made for the common denominator who abuse their knives but we're a different sort and I can't see why the custom makers don't get the most they can out of the steel they use. I know there's a couple guys out there making 1095 knives with a 65+ hrc ground extremely thin and they don't spontaneously combust when the edge is touched to something. Comments welcome
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Hrc of carbon steels
- Thread starter Vicv
- Start date
I remember watching a documentary on Japanese knife making. One of the things that they have encountered when they started exporting their kitchen knives was a significant number of complains and knife returns with busted and chipped blades: something they have never seen before on their domestic market and did not expect at all! That's when they had to come up with a cryogenic treatment (that was for vanadium stainless steel if I remember correctly) to further toughen the steel to combat criminally stupid knife handling practices that people abroad obviously engage in. So what I am saying: Japan is probably not a good example, they have got their own knife usage culture and probably do not even know about batoning, knife throwing and such!
The biggest reason I see is there is a common conception that "proper" hardness for knives is between 57 and 60 HRc for a whole range of steels. The other is a misconception that harder steels are harder to sharpen. While that is perhaps true in an absolute sense, the abrasives in most stones don't really notice much difference between a steel that is 58 and 62. Now, higher hardness steels tend to have more carbides as well, so that has an influence on ease of sharpening. However, these are 2 separate, but related, issues.
Well we shouldn't be buttoning or throwing knives either and that's what I'm getting at. We know better here
That is definitely the misconception but we have so much info now that it shouldn't exist anymore. And I agrees I've never felt harder equates to harder to sharpen. Yes some steels are more difficult than others but a 1095 blade at 58hrc is the same sharpening as white no1 at 64 as long as geometry is the same in my experience
First, how steel are made make significant difference on the behavior of them.
I'm pretty sure most experienced blade-smith will notice the difference between Hitachi's White steel #2 and 1095 in forging... it just noticeable cleaner... less forge scale, harder to move under the hammer and even the inexperience knife guy will be feel that White #2 take sharper and hold better edge than 1095...
Don't let the alloy composition fools you! They are many thing to be considered beside hardness and alloy amount when it come to "performance"
Japanese left their high carbon steel higher HRC than other because of their culture... Japanese trend to give value on thin acute edge that will slice through stuff with ease than obtuse edge than will withstand abuse... You can see this even more clearly on the difference between Japanese and Western chef knife...
Talk about HRC, 52100 stock removal that austenitizing at proper temp and quench in proper speed oil (ParkAAA, Canola oil or alike) will has as quench hardness of 64HRC+... Tempering it one time at 400F and now you have 59-60HRC 52100.
But it will be a difference story to 52100 that has been proper thermal cycled (multi step normalizing) then austenitizing to the same hardness with triple tempering...
HRC of steel does has a big role in characteristic of steel but not everything... How steel are heat treated, the method... are much more importance in my book.
FYI, on high carbon steel, each time of normalizing or quenching, it make steel finer, better grain while reduce the harden ability... W2 that has been quench too much time won't ever take a good hamon until you restart the normalizing cycle... All of these process are quite resource expense, time consume and also come with a risk of distortion...
So its is the maker decision on what they find the most worthwhile for their goal...
I'm pretty sure most experienced blade-smith will notice the difference between Hitachi's White steel #2 and 1095 in forging... it just noticeable cleaner... less forge scale, harder to move under the hammer and even the inexperience knife guy will be feel that White #2 take sharper and hold better edge than 1095...
Don't let the alloy composition fools you! They are many thing to be considered beside hardness and alloy amount when it come to "performance"
Japanese left their high carbon steel higher HRC than other because of their culture... Japanese trend to give value on thin acute edge that will slice through stuff with ease than obtuse edge than will withstand abuse... You can see this even more clearly on the difference between Japanese and Western chef knife...
Talk about HRC, 52100 stock removal that austenitizing at proper temp and quench in proper speed oil (ParkAAA, Canola oil or alike) will has as quench hardness of 64HRC+... Tempering it one time at 400F and now you have 59-60HRC 52100.
But it will be a difference story to 52100 that has been proper thermal cycled (multi step normalizing) then austenitizing to the same hardness with triple tempering...
HRC of steel does has a big role in characteristic of steel but not everything... How steel are heat treated, the method... are much more importance in my book.
FYI, on high carbon steel, each time of normalizing or quenching, it make steel finer, better grain while reduce the harden ability... W2 that has been quench too much time won't ever take a good hamon until you restart the normalizing cycle... All of these process are quite resource expense, time consume and also come with a risk of distortion...
So its is the maker decision on what they find the most worthwhile for their goal...
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I guess it's because I like thin grinds and acute edges. I don't use knives hard. If I have a hard job I will turn to the proper tool. Like instead of batoning I will use an....... ax. And this isn't a western vs Japanese thing I was just using examples as they tend to leave their steel harder and grind thinner. Look at Carter neck knives. 64hrc and in a video he does baton with it so thin hard edges can take more than they're given credit for. Look at Phil Wilson knives. Sure he uses high wear resistant steel but I'm not talking wear resistant. I'm talking compressive strength. O1 at 64hrc I imagine is just as strong and tougher than 10v at that hardness but no one does it. And the whole thermal cycling of 52100 I think is just forgers making their knives sound better. When someone says using bigger stock and more reduction like the steel molecules are getting smashed closer together and the steel is getting denser is laughable. Not to go off topic but 52100 comes perfect from the mill. With stock removal a single normalize and proper austentize/quench will be just as good as a thousand thermal cycles if not better. My opinion anyway
Thermal cycle is not magic, it just science... If you ever have experience as a knife maker with these kind of steel you will know that steel from the mill are far from perfect... to explain about thermal cycle or in other word multi-step normalizing is simple... you heat steel to the point that the grain are total exceedingly growth then cool it down... You heat it again at lower temp to growth the grain again then cool it down... then repeat... and then you have stress relived and almost equally grain structure.
Single normalzing won't ever do the thick in my experience with even with the most forgivable steel like 5160 in stock remoaval...
How you know that O1 at 64HRC will be stronger than CPM10V at the same hardness? It is just your guess or you have scientific back up?
Many of my closest friends are knifemakers and they have done like a hundreds of Bohler'sK460 in every way you can imagine... Molten salt austenitizing to molten salt quench to high speed oil quench to cryo to whatever... and I won't believe that at 64HRC it would be considered anything strong or tough...
Single normalzing won't ever do the thick in my experience with even with the most forgivable steel like 5160 in stock remoaval...
How you know that O1 at 64HRC will be stronger than CPM10V at the same hardness? It is just your guess or you have scientific back up?
Many of my closest friends are knifemakers and they have done like a hundreds of Bohler'sK460 in every way you can imagine... Molten salt austenitizing to molten salt quench to high speed oil quench to cryo to whatever... and I won't believe that at 64HRC it would be considered anything strong or tough...
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Hrc basically is strength. It's resistance to deformation. So as long as o1 and 10v are at the same hardness they're at the same strength. Maybe we use the word strength to mean two different things. At high hardness chipping can be a problem. O1 being much less alloyed and much less carbide should be tougher. Now the cpm process does help the 10v but if o1 is not tougher at equal hardness it shouldn't be less. So at that point the advantage of 10v is abrasion resistance. I don't cut cardboard and rope all days so it's not important to me. What is is edge strength to resist rolls and dents to the edge. A high hrc will accomplish that. Now with higher hardness I can grind the blade thinner as well as the edge and still avoid edge rolling. I know he's not popular here since he's been banned and I'm not a fan boy not even a member of his forum but cliff stamp tested a 1095 knife hardened to 65+ and ground very thin and it performed excellently so it's possible. Also you said with the simple steels a temper of 400 will drop hrc to 59-60. Yes I agree especially if it wasn't fully hardened. OK so temper at 325 and try it. I think the maker would be surprised how well it performed. But alas I'm not a knife maker at this time so this is all speculation. That's why I started this thread. If I'm coming off as a know it all or such I apologize that's not my intent
james terrio
Sharpest Knife in the Light Socket
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- Apr 15, 2010
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Speaking only of handmade/custom stuff... (production blades are typically run soft, for one reason and one reason only: cost. Ease of sharpening and toughness increases are a "bonus", and they're used to great effect for marketing purposes).
It's more about the market, than it is about the maker. Some of these traditions get so ingrained in peoples' minds over the decades that most folks don't really even understand why they became the norm in the first place (again, mostly cost). But whatever... the fact is, blades at 58-60Rc sell better (or at least, to a wider audience) than the same alloys at higher hardnesses.
The influence of Japanese kitchen cutlery and US makers like Wilson is helping dispel some of the old "standards".
Like you, I prefer thinner, more acute edges than most, even in knives that I do use hard, and even abuse. Let's face it, blade design really got about as advanced as it's ever going to get a long time ago, so the fun part is chasing thinner geometries and more durable HT's to eke out that last extra bit of performance.
But we're far from the average buyer, even of custom/handmade knives. A certain percentage of knife buyers are just plain unfamiliar with, and therefore leery of anything they think might be difficult to sharpen or could chip in use. And of course, if one goof manages to break a knife, his pics and angry review will be all over the planet in a matter of days, and suddenly "all XYZ steel at ABC hardness is junk!"
That's not as prevalent today as it was 10 years ago, much less 40 years ago, but they still seem to be in the majority.
I agree with you that nearly any knife in "carbon" steel would benefit from being tempered at 60Rc or in many cases, higher. What's really funny is when people pay extra for high-alloy steels in a search for greater edge retention, then want them run at 58Rc, then can't figure out how the matrix wears away just as fast as a plain "carbon" steel blade does... suddenly they're complaining about "carbide tear-out" and "all stainless steel is junk!"
You're right about that, too. Once it's squeezed down to barstock and leaves the mill, any steel is as "forged to density" as it's ever going to get... as makers, our biggest concern is to not screw it up too much
The main purpose of thermal cycling is to help bring grain size back under control after you've (possibly) blown it up at forging/welding heats and whatnot. Happily, again, "old wives' tales" like edge-packing and "cryo treating" in your kitchen freezer are slowly going away.
It's more about the market, than it is about the maker. Some of these traditions get so ingrained in peoples' minds over the decades that most folks don't really even understand why they became the norm in the first place (again, mostly cost). But whatever... the fact is, blades at 58-60Rc sell better (or at least, to a wider audience) than the same alloys at higher hardnesses.
The influence of Japanese kitchen cutlery and US makers like Wilson is helping dispel some of the old "standards".
Like you, I prefer thinner, more acute edges than most, even in knives that I do use hard, and even abuse. Let's face it, blade design really got about as advanced as it's ever going to get a long time ago, so the fun part is chasing thinner geometries and more durable HT's to eke out that last extra bit of performance.
But we're far from the average buyer, even of custom/handmade knives. A certain percentage of knife buyers are just plain unfamiliar with, and therefore leery of anything they think might be difficult to sharpen or could chip in use. And of course, if one goof manages to break a knife, his pics and angry review will be all over the planet in a matter of days, and suddenly "all XYZ steel at ABC hardness is junk!"
That's not as prevalent today as it was 10 years ago, much less 40 years ago, but they still seem to be in the majority.
I agree with you that nearly any knife in "carbon" steel would benefit from being tempered at 60Rc or in many cases, higher. What's really funny is when people pay extra for high-alloy steels in a search for greater edge retention, then want them run at 58Rc, then can't figure out how the matrix wears away just as fast as a plain "carbon" steel blade does... suddenly they're complaining about "carbide tear-out" and "all stainless steel is junk!"
You're right about that, too. Once it's squeezed down to barstock and leaves the mill, any steel is as "forged to density" as it's ever going to get... as makers, our biggest concern is to not screw it up too much
The main purpose of thermal cycling is to help bring grain size back under control after you've (possibly) blown it up at forging/welding heats and whatnot. Happily, again, "old wives' tales" like edge-packing and "cryo treating" in your kitchen freezer are slowly going away.
For me you seems to well educated on metallurgy especially you are not a knifemaker.
You right about the higher HRC = the more compression strength in theory. But when it come to lateral or tensile strength which are MUCH more important in knife application, the plastic yield stress will play a big role. Steel with higher plastic yield strength at given hardness will be considered a tougher steel.
I would not say that O1 will be stronger than 10V at the same higher hardness. Carbide does play role in strength... better think of why concrete are stronger than pure cement...
Apologize for my bad English, it not my first language anyway.
You right about the higher HRC = the more compression strength in theory. But when it come to lateral or tensile strength which are MUCH more important in knife application, the plastic yield stress will play a big role. Steel with higher plastic yield strength at given hardness will be considered a tougher steel.
I would not say that O1 will be stronger than 10V at the same higher hardness. Carbide does play role in strength... better think of why concrete are stronger than pure cement...
Apologize for my bad English, it not my first language anyway.
@shqxk I'm no metallurgist I just like to read too much. Especially writing from experts like Kevin Cashen and Phil Wilson. I do believe that carbides could increase the strength of a steel but not to the point I'm willing to give up other aspects of plain steels. And I agree on the aspects of different types of strength I'm mostly interested in compressive strength as I don't use my knives hard enough to worry about toughness much. That's why I don't own any infi or 3v
@James I agree with everything you said we're of the same mind. Except your sarcastic assessment of "all stainless is junk." I agree with the people who say that. Of course all my good knives are low alloy steel and all my cheap junk knives are stainless. Could skew my perception a bit
@James I agree with everything you said we're of the same mind. Except your sarcastic assessment of "all stainless is junk." I agree with the people who say that. Of course all my good knives are low alloy steel and all my cheap junk knives are stainless. Could skew my perception a bit
I tend to agree. Japanese culinary knives in general are built lighter, harder, sharper edge and are used in a wider variety of ways than in western cooking. In comparison German knives are softer steel but heavier and thicker. The Japanese have a very long steel culture. They have a specific tool for every purpose. The number of knives designed for cleaning specific fish species is quite remarkable. But you are right that "batoning" makes no sense as they have traditionally had the "Nata" and the "Ono" for chopping wood. A "knife" is considered for cutting. Many Americans also argue that the hatchet is for chopping wood. However, Batoning is well known among Japanese knife fans because this is the 21st century and there is something called the "internet".
https://www.youtube.com/watch?v=46-1Q9k813g
As for throwing knives, which you should not really be doing unless using specifically designed throwing knives, the Shuriken was used in Japan for several centuries, and most of them were straight. Not the stars that Hollywood ninja movies have made famous.
But in a pinch, I suppose any knife will do....
Maker is Hinoura Tsukasa of Tsukasa no Kaiji (Tsukasa Forge) Sanjo City, Niigata Prefecture.
Material is Shirogami No.2
Ya I'm talking 63+. 60+ is good. Maybe I'm worrying about numbers too much. I'm aware hrc isn't the be all end all of knives. Just thinning a knife down from .035 to .015 made a monumental difference in an o1 blade I have but going 4 or so points north would be even better
Thanks.