Talk:Tamahagane

Tamahagane sand is a treasure indeed.

Some of the finest swords in the world are made from it. Some modern replacements are 1090,1080, and 1060 spring steel grades. The numbers are measurements of carbon content in the steel. Most blades have a differential tempering leaving the blade a HRC of 60 on the blade and of 40 towards the back edge. This allows for a razor sharp edge and a softer body for shock absorption.

Not intending to start an arguement, but spring steel really has nothing on tamahagane. The folding process used to combine kawagane and shingane, thus forming tamahagane, is very similar to the modern drop forging techniques used to manufacture steel products which need a lot more strength than plain steel can provide, (ie: a bar of cold rolled steel can be bent rather easily, but a pry bar the same size will take a great, great deal more force to bend), and tools used in high impact environments, like jackhammer bits. Besides, if you want to make a sword out of spring steel, like a good broad sword, I suggest using 4140.Zaereth (talk) 22:44, 11 November 2008 (UTC)

Tamahagane Definition

If I'm not mistaken tamahagane is not formed by folding kawagane and shingane together. In fact, I believe kawagane and shingane are folded seperately and then later pieced together to form the chunk of metal that will eventually become the katana. Tamahagane is merely the kind of steel that is used in constuction of the katana. Also, what is the source for tamahagane meaning "soul of the sword edge steel?" The parsing of tamahagane in the article to get that meaning does not match the usual characters given for the word ("tama" and "hagane,") but it is possible that different classical characters were used in the past. —Preceding unsigned comment added by 219.102.61.204 (talk) 06:16, 19 December 2008 (UTC)

You may be right. After doing some further research, it appears the high carbon steel retrieved from the kera is called Nabe-Gane, and the lower carbon steel is called Hocho-Tetsu, but I'm not an expert on Japanese language. No source I've found is very clear on whether Tamahagane refers to the raw, unrefined steel, or the refined steel, ready for assembly, but it is very clear that the raw steel is very impure, and does not reach any level of quality until the folding process. And it is also clear that the folding incorporates two different kinds of steel, as quoted from "A History of Metallography": "By the introduction of layers of steel of different hardenability and combining this with useful shaping of the coating to give varying local gradients of cooling, very intricately shaped and shaded hard zones can be produced." "The center metal is made of soft steel, indeed often of nearly pure iron, folded upon itself and forged about a dozen times." "The metal that is to form the cutting edge and the adjacent sides is made by taking fragments of very high carbon steel, or perhaps cast iron (previously quenched in water and broken into small pieces to free it from slag), stacking these on a previously made steel plate, forging the whole into a compact flat bar, notching, welding, reforging to the original size, notching and refolding at right angles to the previous folding, and so continuing for about 15 to 20 foldings and weldings." This is a variation of the Chinese method of melting cast iron in a crucible, stacking wrought iron plates in the crucible until almost melted, then folding and forging the metal. To quote from Shen Kua (ca. A.D. 1065) "Ancient people use chi kang, (combined steel), for the edge, and jou thieh (soft iron) for the back, otherwise it would often break. Too strong a weapon will cut and destroy its own edge; that is why it is advisable to use nothing but combined steel."

I will do some more research on the subject to find a clearer definition. As for the translation, I have removed it from the article.Zaereth (talk) 21:17, 19 December 2008 (UTC)

Please check your source on the folding process again; it sounds as if the quotes are taken out of order or from non-related areas. Mikami Sadanao describes the folding process in "The Art of Iron: Forging Japanese Swords" as a process by which the high carbon content kawagane is folded upon itself and then the lower carbon content shingane is folded seperately but in the same fashion. Then the two pieces are pieced together with the harder kawagane bent into a u-shape and the shingane put inside of the u-shape. They are then forged together (but not folded) to make the sunobe that will become the blade. Shingane means something like "core steel" and is used as the center of the blade to prevent breaking, and kawagane (something like "skin steel") is used on the outside because it is better for keeping an edge. If they were further folded together it would undermine the very principle behind making a katana; in essence by making the sword having a uniform make-up none of the benefits of the high carbon and low carbon steels are retained. This may be further explaining in one of the other Wikipedia articles pertaining to katana.

I will look some more into the tamahagane creation process myself. I must admit I'm not an expert on the difference between what unrefined and refined steel are so I'm a bit lost on how that distinction is determined. -Karl —Preceding unsigned comment added by 121.1.157.191 (talk) 13:34, 23 December 2008 (UTC)

Well, I did omit some paragraphs in between, not to be misleading, but because I did not want to quote three entire pages of material, but the vital information is presented in order. The book is worth a read, as it provides very detalied information on the forging process, including illustations from the famous artist Morikawa Chikashige, (done in the late 1800s), which clearly shows the process I've described. The book gives a look at katanas which is presented from a metallurgist's point of view, and as someone who forges katanas, the process described works to provide a sword with a great deal more toughness than a sword in which the kawagane is made from high carbon steel alone. The assembly method you've cited is also described in great detail, to quote: "The carefully prepared steel thus forged was assembled in various ways with the other steel to form the center and back of the blade. Some of the assemblies are shown in Figure 36, although there was almost endless variety possible in the disposition of the different components. The high carbon cover metal was usually folded around the core to avoid a weld intersecting the cutting edge." Zaereth (talk) 18:37, 23 December 2008 (UTC)

I think it might also be worthy to note here that not all katanas are forged with the same level of intricacy, and the price of a blade is often determined by the level of craftsmanship that was put into the blade. A blade with kawagane made of one carbon content shows very little mokume, (wood grain pattern), and produces a smooth nioi, (a thin line about a millimeter wide surrounding the hardened edge of the yakiba), which is made up of niye, (or clusters of bright spots barely visible without a lens, made from the martensitic remnants of single austenite crystals surrounded by pearlite, and thus forms the boundery between the pearlitic blade and the martensitic edge). Instead, the differing layeres of carbon steel will make a nioi that tends to follow the mokume as well as the hamon, which makes a nioi with a 'whispy' sort of appearance, (as seen in the photo), showing that the higher carbon metal was able to achieve a greater level of hardness extending slightly underneath the clay that insulated it during the quenching. A katana forged in this manner will usually cost you over $3000.00. Katanas assembled in the Masamune style, (5 part blade construction, with a soft iron core, but high carbon edge, sides, and back), can cost in the neighborhood of $50,000.00. In this method, steel for the edge is forged with the grain parallel in each layer, but steel for the back is forged with grain in each layer running perpendicular to the next layer, and the sides are forged with the grain running diagonally to the next layer. Zaereth (talk) 19:15, 23 December 2008 (UTC)

Oh, by the way. What I mean by raw, (unrefined), steel, is that kera is full of impurities such as slag, (oxidized iron), phosphorous, silicon, manganese, and such. Also, the carbon content is extremely non-uniform, being higher on the surface, (where it was in contact with the charcoal), and lower in the middle. Steel is usually only formed in the thin branches of molten metal that branch off from the main blob, and thus, could soak up more carbon in the tatara. The steel is refined in the folding by evenly distributing the carbon content, and the mixture of water, clay, and straw applied to the to each plate before the folding acts as a flux, which draws impurities out of the metal with each consecutive welding. As stated in the PBS-Nova special which is referenced in the article, a metallurgical study of the blade shows a level of purity in the refined metal that was unheard of in ancient times. I hope that helps, and any help you could give to improve this article would be appreciated. Zaereth (talk) 20:22, 23 December 2008 (UTC)

It seems interesting to me that Google's translation for the symbols used to spell Tamahagane comes out as "Steel Ball". I found this on a Japanese site, which seems to say that Tamahagane refers to the raw steel. " Steel ball [たまはがね] [It's a once in a while] 砂鉄を原料にして、たたら製鉄でつくられる不純物の少ない鋼のこと。 The raw iron sand, steel made in steel lean TATARA. 日本刀の材料になる。 The material will be a Japanese sword." But, obviously Google's translation leaves much to be desired. I'll keep researching myself. Zaereth (talk) 02:00, 24 December 2008 (UTC)

I do not think that you are trying to be misleading; my apologies if my comments came across like I was. Looking at the page again and some of the sources I'm wondering if the word "folding" isn't getting used in two different senses. One would be the process by which a block of steel is repeatedly folded upon itself, usually around 10 to 14 times. The other sense might be the process by which some smiths used to wrap or "fold" the kawagane around the shingane. It is the idea that the shingane and kawagane are folded upon each other numerous times to make numerous alternating layers that I believe is incorrect.

The character for tama (玉) can mean both jewel and ball, but I think due to the artistic nature of katana-smithing that jewel may be the preferred translation for the term.

This translation may be a bit literal but, 砂鉄を原料にして、たたら製鉄でつくられる不純物の少ない鋼のこと → "A type of steel with few impurities made in a tatara, using satetsu as the raw (base) material." 日本刀の材料になる → "The material with which japanese swords are made." -Karl —Preceding unsigned comment added by 124.154.3.10 (talk) 15:45, 25 December 2008 (UTC)

Thank you for the info. I do believe you're right, that I have used the terms shingane and kawagane incorrectly, and the book can be confusing without the illustrations to clarify what he's talking about. Yes, when talking about the final assembly of the skin and the core, for Amakuni's method, the term 'wrapping' would certainly fit better, (although this is also not the only way, and the book illustrates 5 different possibilities, such as Kunimitsu's and Masamune's method of assembly). But the fact that the skin steel was forged out of two different kinds is clearly described, with pictures. I think again it would be worthy to say that the process described is not the only way to make a katana, and the swords studied in the book are old, (forged between the 1300's and the 1600's). Most modern forging techniques are different. Also, there were several schools in old Japan, (such as the Uda School, and the Hosho School), each one with it's own methods, and each one rather secretive about their own processes. I will quote another paragraph from the book:

"The earliest swords had a straight edge to the yakiba, [talking about the Hamon here], but even before the twelfth century irregular interfaces were produced which had both mechanical and decorative merit. Thereafter appeared a profusion of variants with indentations shaped like cedars, pill boxes, cloves, arrowheads, teeth, rat's feet, etc ., some of which are shown in Figure 39. In the eighteenth century extremely intricate designs became common, with veritable pictures of mountains, (sometimes with snowfields, rivers, and clouds), chrysanthemum flowers, breaking waves with spray, and a hundred others - all protrayed in the metallographer's martensite, in various grains against a background of pearlite! Though the principle means of achieving the effect was the shaping of the clay coat to give local variations in the cooling rate during quenching, [here's the part I described earlier, on the whispy look to the nioi, which can easily be seen in the photo], the incorporation during the forging of streaks of steel of different hardenability in the zone of the temperature gradient was also important, for many fine details are on a scale finer than could be achieved by any possible local variations in thickness or contour of the superficial insulating layer. Lines and streaks of niye away from the hard zone, such as those in Figure 40, clearly result from forged in layers of different metal."

But, please read the book yourself, as I do not wish to quote it all here. It should be available at your local liabrary. It also gives a good look at Damascus Steel, and the Mergovian blades, and other "pattern welded steels", all of which result from using steels of different carbon content.Zaereth (talk) 19:34, 29 December 2008 (UTC)

Here is the process described from a different site, which is sourced in the article: http://www.hitachi-metals.co.jp/e/tatara/nnp0109.htm . It gives the following description of forging of the Kawagane:

"To create a Japanese sword, you start with tama-hagane as the source material and run it through the lapel forging process (shita-kitae). This involves pounding the tama-hagane with a hammer into a flat shape (the mizu-herashi process). The pieces are then piled up, forge welded, and formed into a single block. Next, it is folded lengthwise and forged, and also elongated, cut, lapeled, and then forged again (the shita-kitae process). The iron slag inside is squeezed out during this process, while the remaining slag is broken up into small pieces and spread out. Simultaneously, organic impurities such as phosphorous and sulfur are also extracted.

"Next is the age-kitae (side steel-forging) stage. The tama-hagane, the re-melted pig iron, and the re-melted hocho-iron are folded lengthwise and forged, and also elongated, cut, lapeled, and then forged again to create masses in which the three materials are stacked in grouped and parallel layers (tansatsu-kitae), or in which they are stacked up in alternating and parallel layers (kashigi-kitae), or in which they are stacked in groups and at right angles to each other (konoha-kitae). The metal will be folded dozens of times to go with the shita-kitae process. This produces the side steel, into which the shin-gane(body steel, made up of hocho iron) will be fitted. There are numerous ways of going about this fitting in process as well."

So, it would appear by this the very low carbon steel, (hocho-gane), is very nearly pure iron, and that tamahagane is high quality, medium carbon steel, and that pig iron, (nabe-gane), is extremely high carbon, poor quality steel, (probably very nearly cast-iron), all of which are retrieved from the kera and used for seperate parts of the blade. Hocho-gane is folded several times by itself, to purify it, and is used for the core, where as tamahagane and nabe-gane is forged and folded together to form the skin steel. (Apparently Kawagane and Shingane simply refer to which part of the blade the material is to be used.) Also described here is the different methods for arranging the grain in different layers, as used for different parts of the blade like I have described above.

Much of my info also comes from talking to swordsmiths, and learning the trade, but I'll only present here what I have found verified in books or on respectable internet sites. Here is another site which gives definitions to katana terminology: http://www.samuraisword.com/glossary/index.htm Zaereth (talk) 02:18, 30 December 2008 (UTC)

My main concern remains in the sentence "The most useful process is the folding, where alternating layers of kawagane and shingane are forge welded, folded, and welded again, as many as 16 times" which I read as implying that kawagane and shingane are folded upon each other to produce tamahagane. As you said, kawagane and shingane are so named because of what part of the blade they become in the finished process so if they were folded upon each other they would no longer be the "core" and "skin." I think the sentence I pointed out above should be re-written to avoid confusion.

But since the article in question is really "What is tamahagane?" it seems to me that the pressing issue is that article should be edited or re-written to describe it as the high quality steel used to make katana and perhaps include the process by which the tamahagane itself is made. I think the remainer of your information would probably be helpful in the articles that describe the forging process. -Karl —Preceding unsigned comment added by 124.154.3.10 (talk) 11:54, 4 January 2009 (UTC)

Yes, I agree with that 100%. I know the process used to make the swords very well, but I could use your help to make sure that I have used the Japanese words correctly. Here is a proposed rewrite of the second paragraph:

The swordsmiths will carefully break the kera apart, and separate the various carbon steels. The lowest carbon steel is called hocho-tetsu, which is used for the shingane, (translated as “core-steel”) of the blade. The high carbon tamahagane and higher carbon steel, called nabe-gane, will then be forged in alternating layers, using very intricate methods to form the kawagane, (or, “skin steel”). The most useful process is the folding, where the metals are forge welded, folded, and welded again, as many as 16 times. The folding removes impurities and helps even out the carbon content, while the alternating layers combine hardness with ductility to create toughness. Traditionaly, tamahagane is only made once a year durning winter in a wood building and is only sold to the master swordsmiths to use once it is made.

How does that sound? I think it is useful to make some slight mention of the forging process here, although the more detailed explanation should be in the katana construction article, which could also use some improvement. I have transferred a copy of this discussion to Talk:katana construction, since much of the info contained here can be used to help that article as well.Zaereth (talk) 18:08, 5 January 2009 (UTC)

Looks good to me. Go ahead and put it in. -Karl —Preceding unsigned comment added by 124.154.4.33 (talk) 04:33, 6 January 2009 (UTC)

Done. Thank you for your assistance on this Karl! I have also made similar changes to the katana construction article. Please feel free to comment there too. Your help on this has been most appreciated. Zaereth (talk) 17:15, 6 January 2009 (UTC)

This article needs a little clarification

The statement in this article that the 2.5 ton kera, or steel bloom, produces 2.5 tons of tamahagane is incorrect. I think it should be noted that the kera is mostly mild steel at best, and contains quite a lot of wrought iron, as well as the medium and high carbon steels used in katana smithing. The smith carefully picks over the kera, collecting the shingane, (translated as core-steel), and the kawagane, (or skin-steel). These two steels are combined using very intricate methods, most useful of which is the folding process, to produce tamahagane, (literally translated as "soul of the sword edge-steel"). For a good reference on the subject read the book "A History of Metallography", by Cyril Smith, or check out this detailed website http://www.samuraisword.com/REFERENCE/making/japanse_swordmaking_process.htm . Also, you can find a good documentary on the subject on the PBS website.Zaereth (talk) 22:09, 11 November 2008 (UTC)

Since there have been no objections, I have included this info.Zaereth (talk) 18:45, 1 December 2008 (UTC)

after it is dried, it is dried?

After the clay tub has dried, it is fired until dry.

This makes no sense at all. —Preceding unsigned comment added by 205.250.13.132 (talk) 07:37, 6 January 2009 (UTC)

You're correct. I never even noticed that. How about: After the clay tub has set, it is fired until dry. (I'm not sure what the correct term in ceramics is, but I'll look into it.) Does that sound better?Zaereth (talk) 18:46, 6 January 2009 (UTC)