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Thread: is high carbon steel truly good?

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    Default is high carbon steel truly good?

    the japanese samurai sword makers used both types of steel in the blades, high carbon for its hardness and ability to hold an edge, but also low carbon steel in the same blade for its toughness and ability to absorb the shocks. if only high carbon was used the blade would be brittle, if only low carbon, it would not hold an edge. my question is, some of these modern knives boast high carbon, but are they tempered with low carbon?


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    Senior Member kyratshooter's Avatar
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    We have steels available today that the Japaneese swordsmiths never dreamed of having. They made their swords from laminate because that was what they had.

    I know I will step on some traditional toes here, but that is what the Samori technology is, tradition. There is nothing the matter with tradition, it simply gets mistaken for "perfection" with the passage of time and growth of admiration. Many of the old master crafted blades are have been found littered with flawed welds when x-rayed.

    Todays' techniques and steels? Imagine the strength, durability and toughness of the transmission gears in an M1 Abram tank turned into a knife. You can click the right buttons on your computer and that steel will be delivered to you by the end of the week.

    We can control heat to the fraction of a degree, quinch in liquid nitrogen and temper in ovens filled with inert gas. We can give specific instructions for tempering and annealing and know exactly what the rockwell hardness of the blade will be when we give the instructions on the first blade we ever make.

    They had the eyeball and guess method. That is why it took a lifetime to become a master.

    Even today the "masters" have to scrap a great deal of metal to find the right chunk. What happens to the flawed metal? It gets hammered into simple and cheap blades used by the commoners. Those "perfect" swords cost more than a commoner made in a lifetime.

    When I buy a bar of O2 I never even consider that there might be voids or flaws in the bar. And O2 is not even a complicated specialty steel, just run of the mill stock for this day and age.
    Last edited by kyratshooter; 08-15-2010 at 01:56 PM.
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    reclinite automaton canid's Avatar
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    you do not 'temper' with low carbon. you temper by heat treatment.

    low carbon steels and even cast iron are suitable for many purposes, and they have been incorporated into many cutting tools, but carbon, or other alloying agents which increase the hardness of iron must be present to have a strong cutting edge.

    you face a bit of a dillema, as milder steels are tougher, and higher hardness steels are more brittle, but by balancing the alloy composition with a suitable temper, you can reach a fair compromise which is suitable for a given cutting task.

    high carbon steel can always -be made softer and more ductile by heat treatment, but mild steel can not be made harder than it's full-hard state.
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    Quote Originally Posted by hunter63 View Post
    I do have several primitive bags belts and other buck-skinner gear made for "urban buffalo hide".

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    What candid said
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    2%er Erratus Animus's Avatar
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    One other thing is that during the process of making the sword carbon is lost from the outside of the blade. Starting with a higher carbon content allows the smith to reach the correct amount for the style of blade he was making. there is also a migration of carbon atoms every time the steel is folded in order to make homogenization of the metals complete.

    The steels of sword from those eras 1700- early 1900's has been inspected with gas chromographers. Basically a camera that burns the metal in order to read the compounds in the metal. It has been determined that those steels are inferior to modern steels and it is also mentioned that the magical qualities attributed to some makers were due in part too a higher carbon content and a better heat treating.

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    Administrator Rick's Avatar
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    Thanks to all who responded. This was a very informative post and I learned a bunch about metals. Thanks!

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    Senior Member Winter's Avatar
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    I could spend an hr answering the original post itself, but the thread title is easier to answer.

    YES. High carbon steels are the best IMO. They are easily sharpened with field expedient methods. They resist breaking better from my experience.

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    Senior Member Camp10's Avatar
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    Quote Originally Posted by coldlightning View Post
    the japanese samurai sword makers used both types of steel in the blades, high carbon for its hardness and ability to hold an edge, but also low carbon steel in the same blade for its toughness and ability to absorb the shocks. if only high carbon was used the blade would be brittle, if only low carbon, it would not hold an edge. my question is, some of these modern knives boast high carbon, but are they tempered with low carbon?
    I think KRS did a great job answering this. Let me try my hand at a basic explaination. The swords were made by sorting the different pieces of the same batch of steel. The steel that was used was a very simple and crude carbon steel. They would take the various lumps of steel and strike them with a hammer. Some would bend and others would break. Just having this much of a variation in a single batch of steel should tell you it wasnt good stuff. The ones that broke were used for the center of the blade and the ones that would bend were the for the outer wrap. The theory was that the higher carbon would leave the steel brittle so if it were to break, it was of high carbon and for the edge. The two steels were forged seperate into billets and then the softer, low carbon steel was wrapped around the other and forge welded into one billet.

    Todays steels are much better. Many custom knifemakers that work with carbon steels will differentially treat their blades and get a similar effect. A blade now can be made with an edge hardness of (just an example) 60 on the rockwell c scale and with a spine in the 30's or 40's. This will give the same effect but with a single steel type.

    Modern steels will harden too much for a knife application and will need to be drawn back to be useful. This is what tempering is, all knifemakers shoot for full hardness on their quench and "fix it" with the temper.

    Laminating is still used by mastersmiths (at least for their test knives). What laminating does is keep spine from hardening at all so the edge doesnt have to be drawn back nearly as much to still keep the knife functional. It only requires enough tempering heat to stabilize the structure of the edge. so in my differentially treated example of a blade at 60 Rc on the edge and a spine at 40, a good bladesmith can make a laminated blade with todays metals (again, just an example)with an edge of 64 Rc and a spine at 20. They pick their steels with a little more science though.

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    reclinite automaton canid's Avatar
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    it is completely unfair to say that such bloomery steel isn't good stuff, just because it is not a homogeneous smelted product. it is a relatively simple proccess, but tamahagane is fine steel, and the black sand ore it is made from results in a purer product than much steel produced by similar methods in other parts of the world.

    tamahagane, wootz, shear steel, etc are not inherently inferior because the technologies which produce them are simpler. that they are less predictable is well compensated by the control of the proccess of manufacture of the tools made from them. the proper test is the performance of the end-product, and such materials have made a great many fine tools and weapons.

    a bicycle is a great mode of transportation too, despite being simpler than a combustion engine driven vehicle.
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    Quote Originally Posted by hunter63 View Post
    I do have several primitive bags belts and other buck-skinner gear made for "urban buffalo hide".

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    Super Moderator crashdive123's Avatar
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    Very informative indeed. I just find a chunk of metal and try and put an edge on it.
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    sorry for taking forever to respond, lost my internet connection for awhile. man, i just want to say you guys are awesome! your knowledge is incredible. as is today's metallurgical technology. beyond belief to me.wow. so many steel types for so many different applications. ok so here's a question, which type holds an edge best when used for skinning, and cleaning of fish, etc.?

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    Senior Member kyratshooter's Avatar
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    NCO is banned from offering comments in this post.

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    Senior Member Camp10's Avatar
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    Quote Originally Posted by coldlightning View Post
    ok so here's a question, which type holds an edge best when used for skinning, and cleaning of fish, etc.?
    That "Etc" makes a big different in how I might answer. Everyone who has made a knife will give you a different answer. The big problem is, they probably are all going to be mostly right. I am usually after flexibility for a fillet knife. They seem to hold an edge pretty good if they are just being used on fish so you can substitute a little hardness for toughness. I like ATS-34 and temper is a little soft (for that steel, I would go with a 450 degree temper on a fillet knife and a 900 degree temper for a skinner).

    If you are asking about any knife steel that holds an edge the best, you are looking for D-2 or 52100 for carbon steel and CPM S30V or BG-42 for stainless. These are the ones I am most familiar with (I've never used BG-42 but know it's properties) but other makers will give you different answers most likely.

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    Junior Member JCavSD's Avatar
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    Hi all. First post here and looking forward to exploring this site.

    I may not be clear on the original question. Is low carbon steel used for knife blades? Isn't it usually a question of "high carbon" vs. stainless?

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    Senior Member Camp10's Avatar
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    Quote Originally Posted by JCavSD View Post
    Hi all. First post here and looking forward to exploring this site.

    I may not be clear on the original question. Is low carbon steel used for knife blades? Isn't it usually a question of "high carbon" vs. stainless?
    Yeah.

    Low carbon steel is used in some laminated blades but it is folded in with high carbon steel. There are also so many, many different variations of high carbon steel and how much carbon is "high"? As I post all the time, stainless steel used in knifemaking is high carbon steel, it just has other alloys in it that make it stain resistant as well.
    Last edited by Camp10; 08-28-2010 at 09:33 PM.

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    Quote Originally Posted by crashdive123 View Post
    Very informative indeed. I just find a chunk of metal and try and put an edge on it.
    I just buy mine already made!
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    Quote Originally Posted by Camp10 View Post
    As I post all the time, stainless steel used in knifemaking is high carbon steel, it just has other alloys in it that make it stain resistant as well.
    Yea, that's why I put "high carbon" in quotes. Chromium is the key element in determining whether a steel is "high carbon" (common terminology, going to have to live with it) or stainless. Around 13% is the breakoff. Didn't know that low carbon was used in some laminated blades...doesn't seem like wise route.

    You all may already be familiar with this site, but if not it has some good info on steel in a pretty easy to manage format. http://zknives.com/knives/steels/steelchart.php

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    Senior Member Camp10's Avatar
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    Quote Originally Posted by JCavSD View Post
    Yea, that's why I put "high carbon" in quotes. Chromium is the key element in determining whether a steel is "high carbon" (common terminology, going to have to live with it) or stainless.
    It's the carbon that makes steel high carbon. Chromium is an element that can be added. It adds hardness and wear resistance to the blade, so does vanadium. Silicon is added for toughness. Molybdenum is another element used. It's can help form stable carbides making a more uniform blade. There is also tungsten, nickle, manganese, etc, etc all which add different properties to the blades.

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    Junior Member JCavSD's Avatar
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    Quote Originally Posted by Camp10 View Post
    It's the carbon that makes steel high carbon. Chromium is an element that can be added. It adds hardness and wear resistance to the blade, so does vanadium. Silicon is added for toughness. Molybdenum is another element used. It's can help form stable carbides making a more uniform blade. There is also tungsten, nickle, manganese, etc, etc all which add different properties to the blades.
    Right, what I guess I was trying to say is that, although a "high carbon" and a stainless steel may have identical carbon content, it's the addition of a certain amount of chromium, among other elements, that makes a steel stainless.
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