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The intro is a bit over-broad. That material is mostly covered in Katana, like the discussion of daisho fittings; it should be a bit more focused on the contruction article that follows. Just an area that needs a little work. jesup 14:01, 29 November 2006 (UTC)
I don't know what a daisho is and it's not explicitly explained. Don't you think the article is a bit nerdy? —Preceding unsigned comment added by 193.36.79.207 ( talk) 09:56, 4 November 2008 (UTC)
I greatly rewrote the section on repros; it should probably be moved to lower in the page, and could use a little more work. jesup 15:02, 29 November 2006 (UTC)
I've written a major revision of the polishing section, using summarized information gleaned from my latest purchase. I was wondering how it could be improved further before being formally appended into the main article, if or when it becomes good enough to be added. CABAL 17:55, 16 December 2006 (UTC)
The article says: "however, the belief that the layered structure provides enhanced mechanical properties of the steel is false, as layers act as weld points which can only serve to weaken the integrity of the blade".
I have read quite the contrary on that point. By interposing a layer of slippery graphite between each pair of layers of steel, the steel layers can slide relative to one another (only by a molecular distance, but it adds up). This makes the blade flexible and not brittle, while still allowing it to be very sharp. —Preceding unsigned comment added by 66.14.154.3 ( talk) 16:43, 8 May 2008 (UTC)
Could you provide a source for that claim? It doesn't sound too plausible.-- Caliburnis ( talk) 22:44, 13 May 2008 (UTC)
I really know little about this topic, but I read that blades were certified according to how well they could cut a man. The highest certification was when a blade was tested on a live subject and was able to slice him hip to hip. Is there any truth to this and how could we add it to the article? —Preceding unsigned comment added by 67.193.129.196 ( talk) 00:44, 3 June 2008 (UTC)
Blades were known to be tested and "certified" based on how many cadavers they could cut through. Cutting a single body hip to hip would have been no great achievement. There are records of swords that could cut four or five bodies in a single stroke. —Preceding unsigned comment added by Drosera99 ( talk • contribs) 15:15, 30 September 2008 (UTC)
I think that this article doesn't need an article of its own. Frankly, the Katana article is shorter.
Katana making is a long and intricate process and wikipedia should have seperate page to elaberate on its process, merging it would be like merging an article on film directing with the motion picture page. 209.244.31.42 ( talk) 20:32, 27 September 2008 (UTC)
Disagree, i've browsed many other forms of weaponry on here, and none of them have a seperate link describing the process of making them. —Preceding unsigned comment added by 74.183.150.4 ( talk) 06:23, 24 January 2009 (UTC)
I think it should be noted that one of the main purposes for folding the steel, other than purification, is to provide alternating layers of steel with different hardenability. Typically, a block of extremely high carbon steel is welded to a block of medium carbon steel, then folded from there. The number and method of folding determines the grain direction and courseness. Typically, 10 to 14 folds are used, (number and method depending on what part of the blade the steel will be used). After 16, (65,536 individual layers), the act of folding no longer gives any benefit to the steel. The alternating layers back each other up, which combines hardness with ductility to create toughness. A good book on the subject is called "A History of Metallography", by Cyril Smith. Or check out this detailed website: http://www.samuraisword.com/REFERENCE/making/japanse_swordmaking_process.htm Zaereth ( talk) 22:18, 2 October 2008 (UTC)
It is also interesting, but not necessary, to note that the drop-forging used in things like pry-bars and jackhammer-bits is very similar to the ancient folding tecniques, (which is why a steel bar can easily be bent, but good luck bending that pry-bar of the same size). Zaereth ( talk) 22:32, 2 October 2008 (UTC)
http://en.wikipedia.org/wiki/Image:Katana_-_showing_alternating_layers.JPG Here is a photo I took of my sword, (very hard to capture on film), showing the alternating layers. The layers of darker color have less carbon content, while the layers of lighter color, (those that closely match the hamon), have a higher carbon content. Close inspection shows that these layers extend past the hamon into the hardened edge. I don't know how to upload this picture here, but it's free to use in this or any other article. Zaereth ( talk) 01:02, 3 October 2008 (UTC)
It might be helpful to note in this section, especially for those of us who actually own a shin ken, (real sword), that one should never polish the tang. Doing so will extremely devalue the sword. Zaereth ( talk) 23:16, 2 October 2008 (UTC)
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)
I have edited this article to represent the process discussed here. Zaereth ( talk) 18:26, 6 January 2009 (UTC)
The following lines in the "Construction" section are not entirely accurate. "If steel cools quickly, from a hot temperature, it becomes martensite, which is very hard but brittle. Slower, from a lower temperature, and it becomes pearlite, which bends easily and does not hold an edge."
To harden steel, it must be heated above the austenite transformation temperature, (1400 to 1500 degrees F). At this temp, austenite crystals form, and grow larger as temperature increases. (Smaller crystals make stronger metal, so the steel is not usually heated much beyond the A1 temp, although katanas were often heated to as much as 1600oF. Also, before quenching the steel also needs to be annealed, or better yet, spheroidized, to ensure crystal growth from the smallest possible size.) Controlling crystal size helps to increase the shear and tensile strength of the metal.
The hardness of the steel is solely a function of cooling time. The faster the metal is cooled from the A1 temp, the harder it becomes. Crystal size, on the other hand, is largely unaffected by cooling rate and will be the same in the edge or the back. According to A History of Metallography, and a PBS special referenced in the article, the thickness of the clay coating on the edge and the back, and even the temperature of the quenching water, were often carefully guarded secrets, fine tuned by the various schools to produce the correct hardness without any further need of tempering!
I am removing the temperature info from the sentences so as not to confuse the issue. The new sentences will read: "If steel cools quickly it becomes martensite, which is very hard but brittle. Slower and it becomes pearlite, which bends easily and does not hold an edge."
If there are any questions or comments please leave them here. Zaereth ( talk) 00:29, 1 September 2009 (UTC)
I found this diagram on the French wikipedia. It looks to me to be far mor accurate at depicting the different methods of assembling the different steels during the final forging. I think we should replace the one we have with this one. Does anyone agree/disagree? Zaereth ( talk) 21:23, 25 September 2009 (UTC)
Since there has been no opposition, I have implimented the suggested changes. Zaereth ( talk) 21:57, 15 October 2009 (UTC)
The information added today, to an entirely unsourced section, is also completely unsourced: "The pupose rather, for the grooves, is in the instance of stabbing an opponent the blade could get stuck due to the fact that the inside of the torso is like a vacuum, so the grooves allow air to flow freely into the torso eliminating the vacuum effect making easier to pull the blade of of the opponent."
I have never heard of such a thing, as it sounds more like urban legend. The small surface area, shape of the sword, and physical structure of the body seem to negate this, (a body is under pressure, not vacuum). It also directly contradicts the sentence just prior: "It leads to no demonstrable difference in ease withdrawing a blade nor reduce the sucking sound that many people believe was the reason for including such a feature in commando knives in World War II."
I'll see if I can find sources for this information, but I believe the only purpose for the grooves, as far as I've read, is that they lower the weight which allows for faster movement. This is also expressed in the sentence: "The grooves are analogous in structure to an I beam, lessening the weight of the sword yet keeping structural integrity and strength."
If anyone has any sources to confirm any of this info, it would be appreciated. Zaereth ( talk) 22:01, 26 October 2009 (UTC)
According the the fuller article and the source located here,the "blood groove" section of the article is complete bunk. Removing sentence. -- Anima Rytak ( talk) 04:40, 10 December 2009 (UTC)
There is often much confusion between the terms "tempering" and "hardening." Even Roberts-Austen, (for whom austenite was named after), was known to comment on this confusion. In a speech given in 1889, Roberts-Austen said, ""There is still so much confusion between the words "temper," "tempering," and "hardening," in the writings of even eminent authorities, that it is well to keep these old definitions carefully in mind. I shall employ the word tempering in the same sense as softening." In blacksmithing as well as the field of metallurgy, this is what tempering refers to, that is, the softening of steel after hardening, but not the hardening process itself. Hardening is referred to as "quenching."
The differential process used for heat treating a Japanese sword is done during the quenching, or hardening phase. In this process, more accurately referred to as "differential hardening" or "differential quenching," the sword is cooled at different rates during quenching, producing the difference in hardness. The back of the blade becomes pearlite, while the edge is transformed into martensite. If done correctly, (ie: using the proper clay thickness and water temperature to control the cooling speed), the proper hardness can be achieved without the need for further tempering, although, more often, some traditional tempering will be required after quenching.
"Differential tempering," on the other hand, more accurately refers to the process used after quenching. Tempering refers to the subsequent heating to around 400 degrees F, to soften the martensite and provide some elasticity and ductility. In this method, the fully hardened steel is heated in a localized area, so that the spine of the blade gets hotter than the edge, providing different amounts of softening across the blade. In this method, the entire blade is transformed into martensite, and then differentially heated to form different degrees of "tempered martensite" across the blade.
The book Knife Talk II: The high performance blade, by Ed Fowler, has a whole chapter describing the differences between differential tempering and differential hardening. A History of Metallography, by Cyril Smith, is also an excellent book about katana, their manufacture, and their metallurgical qualities. This website also gives a pretty good description. I don't mean to be nit-picky, but there is a ton of confusion out there about the meaning of the word "tempering," and how it differs from "quenching," so I prefer to be as accurate as possible in the choice of wording that is used in this article. Zaereth ( talk) 06:38, 3 May 2012 (UTC)
- There seems to be some confusion concerning the distinction between differential hardening and differential tempering. First I'll define the terms, then I'll discuss my opinion concerning the merits of the two methods of developing a blade of variable hardness. The following discussion applies 'only to 5160 and 52100 steels. Other steels may respond differently.
- Definitions
- The three main terms to define are tempering, differential tempering and differential hardening.
- 1) Tempering a Blade: This procedeure consists of heating a hardened blade to the desired temperature to make it more resilient to stress.
- 2) Differential tempering: Starting with a blade that has been fully hardened, the bladesmith heats the spine or back of the blade to make it softer than the cutting edge. The object is to provide greater toughness to the blade.
- 3) Differential hardening: In this procedure, only part of the blade is hardened, then the entire blade is usually tempered.
- "Typically modern swords are through-tempered, i.e. the same hardness all the way through. These swords ideally range between HRc50 to HRc54. This usually provides good compromise hardness for edge retention, shock resistance and flexibility. Some swords are selectively hardened like Japanese swords-- these will be around HRc56-60 at the cutting edge, but the spine of the blade will be quite soft. This isn't ideal for European swords, as they can easily bend if the blow is a little off when striking a target or parrying an opponent's attack. A third method I often use is called differential tempering.The whole blade is brought to a temper that is quite high for a sword blade (HRc58-60) and then selected areas of the sword, the spine and tang, are tempered to a low hardness (HRc45-48) leaving the cutting edge at the higher hardness.
Murray Carter is an excellent bladesmith, but he makes knives, not swords. He is not a licensed swordsmith, nor does the article cited assert this. Yoshimoto is the family lineage of knife smiths of which he is the successor. This is not the same as being a licensed swordsmith by the Japanese government. — Preceding unsigned comment added by 126.209.98.76 ( talk) 05:44, 7 April 2013 (UTC)
The article stated: The composition of steel used for the Japanese sword varied from smith to smith and lode to lode of iron ore. One formula from World War II shin guntō production was as follows:
Elemental composition: | |
Iron | 95.22% to 98.12% |
Carbon | 0.32% to 3.00% |
Cobalt | 1.54% |
Manganese | 0.11% |
Tungsten | 0.05% |
Molybdenum | 0.04% |
Titanium | 0.02% |
Silicon | Varying amount |
Miscellaneous compounds | Trace amount |
There is no source, and the range in carbon content is too wide to make any sense. This is not steel used for swordmaking. Further, a carbon content of 3% is far too high, and I do not believe the cobalt content either. -- Zz ( talk) 11:20, 2 August 2013 (UTC)
{{
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help); Unknown parameter |trans_title=
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help)CS1 maint: numeric names: editors list (
link)Ok, I took some time to search through my sources. I cannot find the source on the WWII swords. For clarification, to differentiate them from traditionally made swords, the Japanese term for factory -made swords for military use is "gunto." I'm not sure these need to be detailed in this article.
For traditionally-made swords, Hitach Steel provides a good source for the composition of the raw materials. However, for the composition of the final, refined steel, Dr. Tawara seems to be the foremost expert, but I do not have access to his research. Cyril Smith, on the other hand, did an analysis of his own, on four different swords. The results are arranged by the age of the particular sword, and do not account for local variations in hardenability. These results are as follows:
As you can see, there is little variation in these numbers, and the levels of impurities like silicon and phosphorous is lower than most modern steels. piaskowski also did a study by sectioning a sword, revealing an average of .6 to .8% carbon at the edge and skin, but only .2% at the core.
I hope that helps provide a more accurate chart. This info can be found in the book, The Sword and the Crucible: A History of the metallurgy of European swords up to the 16th century by Alan Williams, page 42--43. I'm not good with charts, so someone else will need to change the numbers. Zaereth ( talk) 00:21, 6 August 2013 (UTC)
Right now the article has
"The high carbon steel, called tamahagane, and the remelted pig iron, called nabe-gane, are combined..."
Followed later by
"The nabe-gane is heated, quenched in water, and then broken into small pieces to help free it from slag. The tamahagane is then forged into a single plate, and the pieces of nabe-gane are piled on top..."
I found this hard to follow. I think that this would be better:
"The pig iron is heated, quenched in water, and then broken into small pieces to help free it from slag. The high carbon steel is then forged into a single plate, and the pieces of pig iron are piled on top..."
This avoids having to go back to a previous paragraph to find out what the Japanese words mean. -- Guy Macon ( talk) 18:44, 22 October 2015 (UTC)
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One of the bullet points of the benefits of folding claims that it homogenizes the steel. I am confident that it is simply NOT TRUE that the layers are compositionally identical. In fact, what I've read directly contradicts this, claiming that the layers ARE of different composition (different ratio of elements). One other thing I didn't see is the difference between Japanese swordsmithing, and of the specific ("traditional") way the katana and similar blades were/are made. It isn't plausible, imho, that every single sword made in Japan - ever - followed the process described here. I suggest a discussion is in order about what this article is really about, which is a specific type (school?) of Japanese swordsmithing. 98.21.221.175 ( talk) 08:51, 6 May 2018 (UTC)
At what point does the blade get its cutting edge and how is it sharpened? Is this part of the 'polishing'? Absolutely no mention is made of this either in this article or the one on polishing which is odd given that the whole purpose of a sword is to support a cutting edge. 212.159.76.165 ( talk) 15:15, 2 December 2019 (UTC)
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The intro is a bit over-broad. That material is mostly covered in Katana, like the discussion of daisho fittings; it should be a bit more focused on the contruction article that follows. Just an area that needs a little work. jesup 14:01, 29 November 2006 (UTC)
I don't know what a daisho is and it's not explicitly explained. Don't you think the article is a bit nerdy? —Preceding unsigned comment added by 193.36.79.207 ( talk) 09:56, 4 November 2008 (UTC)
I greatly rewrote the section on repros; it should probably be moved to lower in the page, and could use a little more work. jesup 15:02, 29 November 2006 (UTC)
I've written a major revision of the polishing section, using summarized information gleaned from my latest purchase. I was wondering how it could be improved further before being formally appended into the main article, if or when it becomes good enough to be added. CABAL 17:55, 16 December 2006 (UTC)
The article says: "however, the belief that the layered structure provides enhanced mechanical properties of the steel is false, as layers act as weld points which can only serve to weaken the integrity of the blade".
I have read quite the contrary on that point. By interposing a layer of slippery graphite between each pair of layers of steel, the steel layers can slide relative to one another (only by a molecular distance, but it adds up). This makes the blade flexible and not brittle, while still allowing it to be very sharp. —Preceding unsigned comment added by 66.14.154.3 ( talk) 16:43, 8 May 2008 (UTC)
Could you provide a source for that claim? It doesn't sound too plausible.-- Caliburnis ( talk) 22:44, 13 May 2008 (UTC)
I really know little about this topic, but I read that blades were certified according to how well they could cut a man. The highest certification was when a blade was tested on a live subject and was able to slice him hip to hip. Is there any truth to this and how could we add it to the article? —Preceding unsigned comment added by 67.193.129.196 ( talk) 00:44, 3 June 2008 (UTC)
Blades were known to be tested and "certified" based on how many cadavers they could cut through. Cutting a single body hip to hip would have been no great achievement. There are records of swords that could cut four or five bodies in a single stroke. —Preceding unsigned comment added by Drosera99 ( talk • contribs) 15:15, 30 September 2008 (UTC)
I think that this article doesn't need an article of its own. Frankly, the Katana article is shorter.
Katana making is a long and intricate process and wikipedia should have seperate page to elaberate on its process, merging it would be like merging an article on film directing with the motion picture page. 209.244.31.42 ( talk) 20:32, 27 September 2008 (UTC)
Disagree, i've browsed many other forms of weaponry on here, and none of them have a seperate link describing the process of making them. —Preceding unsigned comment added by 74.183.150.4 ( talk) 06:23, 24 January 2009 (UTC)
I think it should be noted that one of the main purposes for folding the steel, other than purification, is to provide alternating layers of steel with different hardenability. Typically, a block of extremely high carbon steel is welded to a block of medium carbon steel, then folded from there. The number and method of folding determines the grain direction and courseness. Typically, 10 to 14 folds are used, (number and method depending on what part of the blade the steel will be used). After 16, (65,536 individual layers), the act of folding no longer gives any benefit to the steel. The alternating layers back each other up, which combines hardness with ductility to create toughness. A good book on the subject is called "A History of Metallography", by Cyril Smith. Or check out this detailed website: http://www.samuraisword.com/REFERENCE/making/japanse_swordmaking_process.htm Zaereth ( talk) 22:18, 2 October 2008 (UTC)
It is also interesting, but not necessary, to note that the drop-forging used in things like pry-bars and jackhammer-bits is very similar to the ancient folding tecniques, (which is why a steel bar can easily be bent, but good luck bending that pry-bar of the same size). Zaereth ( talk) 22:32, 2 October 2008 (UTC)
http://en.wikipedia.org/wiki/Image:Katana_-_showing_alternating_layers.JPG Here is a photo I took of my sword, (very hard to capture on film), showing the alternating layers. The layers of darker color have less carbon content, while the layers of lighter color, (those that closely match the hamon), have a higher carbon content. Close inspection shows that these layers extend past the hamon into the hardened edge. I don't know how to upload this picture here, but it's free to use in this or any other article. Zaereth ( talk) 01:02, 3 October 2008 (UTC)
It might be helpful to note in this section, especially for those of us who actually own a shin ken, (real sword), that one should never polish the tang. Doing so will extremely devalue the sword. Zaereth ( talk) 23:16, 2 October 2008 (UTC)
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)
I have edited this article to represent the process discussed here. Zaereth ( talk) 18:26, 6 January 2009 (UTC)
The following lines in the "Construction" section are not entirely accurate. "If steel cools quickly, from a hot temperature, it becomes martensite, which is very hard but brittle. Slower, from a lower temperature, and it becomes pearlite, which bends easily and does not hold an edge."
To harden steel, it must be heated above the austenite transformation temperature, (1400 to 1500 degrees F). At this temp, austenite crystals form, and grow larger as temperature increases. (Smaller crystals make stronger metal, so the steel is not usually heated much beyond the A1 temp, although katanas were often heated to as much as 1600oF. Also, before quenching the steel also needs to be annealed, or better yet, spheroidized, to ensure crystal growth from the smallest possible size.) Controlling crystal size helps to increase the shear and tensile strength of the metal.
The hardness of the steel is solely a function of cooling time. The faster the metal is cooled from the A1 temp, the harder it becomes. Crystal size, on the other hand, is largely unaffected by cooling rate and will be the same in the edge or the back. According to A History of Metallography, and a PBS special referenced in the article, the thickness of the clay coating on the edge and the back, and even the temperature of the quenching water, were often carefully guarded secrets, fine tuned by the various schools to produce the correct hardness without any further need of tempering!
I am removing the temperature info from the sentences so as not to confuse the issue. The new sentences will read: "If steel cools quickly it becomes martensite, which is very hard but brittle. Slower and it becomes pearlite, which bends easily and does not hold an edge."
If there are any questions or comments please leave them here. Zaereth ( talk) 00:29, 1 September 2009 (UTC)
I found this diagram on the French wikipedia. It looks to me to be far mor accurate at depicting the different methods of assembling the different steels during the final forging. I think we should replace the one we have with this one. Does anyone agree/disagree? Zaereth ( talk) 21:23, 25 September 2009 (UTC)
Since there has been no opposition, I have implimented the suggested changes. Zaereth ( talk) 21:57, 15 October 2009 (UTC)
The information added today, to an entirely unsourced section, is also completely unsourced: "The pupose rather, for the grooves, is in the instance of stabbing an opponent the blade could get stuck due to the fact that the inside of the torso is like a vacuum, so the grooves allow air to flow freely into the torso eliminating the vacuum effect making easier to pull the blade of of the opponent."
I have never heard of such a thing, as it sounds more like urban legend. The small surface area, shape of the sword, and physical structure of the body seem to negate this, (a body is under pressure, not vacuum). It also directly contradicts the sentence just prior: "It leads to no demonstrable difference in ease withdrawing a blade nor reduce the sucking sound that many people believe was the reason for including such a feature in commando knives in World War II."
I'll see if I can find sources for this information, but I believe the only purpose for the grooves, as far as I've read, is that they lower the weight which allows for faster movement. This is also expressed in the sentence: "The grooves are analogous in structure to an I beam, lessening the weight of the sword yet keeping structural integrity and strength."
If anyone has any sources to confirm any of this info, it would be appreciated. Zaereth ( talk) 22:01, 26 October 2009 (UTC)
According the the fuller article and the source located here,the "blood groove" section of the article is complete bunk. Removing sentence. -- Anima Rytak ( talk) 04:40, 10 December 2009 (UTC)
There is often much confusion between the terms "tempering" and "hardening." Even Roberts-Austen, (for whom austenite was named after), was known to comment on this confusion. In a speech given in 1889, Roberts-Austen said, ""There is still so much confusion between the words "temper," "tempering," and "hardening," in the writings of even eminent authorities, that it is well to keep these old definitions carefully in mind. I shall employ the word tempering in the same sense as softening." In blacksmithing as well as the field of metallurgy, this is what tempering refers to, that is, the softening of steel after hardening, but not the hardening process itself. Hardening is referred to as "quenching."
The differential process used for heat treating a Japanese sword is done during the quenching, or hardening phase. In this process, more accurately referred to as "differential hardening" or "differential quenching," the sword is cooled at different rates during quenching, producing the difference in hardness. The back of the blade becomes pearlite, while the edge is transformed into martensite. If done correctly, (ie: using the proper clay thickness and water temperature to control the cooling speed), the proper hardness can be achieved without the need for further tempering, although, more often, some traditional tempering will be required after quenching.
"Differential tempering," on the other hand, more accurately refers to the process used after quenching. Tempering refers to the subsequent heating to around 400 degrees F, to soften the martensite and provide some elasticity and ductility. In this method, the fully hardened steel is heated in a localized area, so that the spine of the blade gets hotter than the edge, providing different amounts of softening across the blade. In this method, the entire blade is transformed into martensite, and then differentially heated to form different degrees of "tempered martensite" across the blade.
The book Knife Talk II: The high performance blade, by Ed Fowler, has a whole chapter describing the differences between differential tempering and differential hardening. A History of Metallography, by Cyril Smith, is also an excellent book about katana, their manufacture, and their metallurgical qualities. This website also gives a pretty good description. I don't mean to be nit-picky, but there is a ton of confusion out there about the meaning of the word "tempering," and how it differs from "quenching," so I prefer to be as accurate as possible in the choice of wording that is used in this article. Zaereth ( talk) 06:38, 3 May 2012 (UTC)
- There seems to be some confusion concerning the distinction between differential hardening and differential tempering. First I'll define the terms, then I'll discuss my opinion concerning the merits of the two methods of developing a blade of variable hardness. The following discussion applies 'only to 5160 and 52100 steels. Other steels may respond differently.
- Definitions
- The three main terms to define are tempering, differential tempering and differential hardening.
- 1) Tempering a Blade: This procedeure consists of heating a hardened blade to the desired temperature to make it more resilient to stress.
- 2) Differential tempering: Starting with a blade that has been fully hardened, the bladesmith heats the spine or back of the blade to make it softer than the cutting edge. The object is to provide greater toughness to the blade.
- 3) Differential hardening: In this procedure, only part of the blade is hardened, then the entire blade is usually tempered.
- "Typically modern swords are through-tempered, i.e. the same hardness all the way through. These swords ideally range between HRc50 to HRc54. This usually provides good compromise hardness for edge retention, shock resistance and flexibility. Some swords are selectively hardened like Japanese swords-- these will be around HRc56-60 at the cutting edge, but the spine of the blade will be quite soft. This isn't ideal for European swords, as they can easily bend if the blow is a little off when striking a target or parrying an opponent's attack. A third method I often use is called differential tempering.The whole blade is brought to a temper that is quite high for a sword blade (HRc58-60) and then selected areas of the sword, the spine and tang, are tempered to a low hardness (HRc45-48) leaving the cutting edge at the higher hardness.
Murray Carter is an excellent bladesmith, but he makes knives, not swords. He is not a licensed swordsmith, nor does the article cited assert this. Yoshimoto is the family lineage of knife smiths of which he is the successor. This is not the same as being a licensed swordsmith by the Japanese government. — Preceding unsigned comment added by 126.209.98.76 ( talk) 05:44, 7 April 2013 (UTC)
The article stated: The composition of steel used for the Japanese sword varied from smith to smith and lode to lode of iron ore. One formula from World War II shin guntō production was as follows:
Elemental composition: | |
Iron | 95.22% to 98.12% |
Carbon | 0.32% to 3.00% |
Cobalt | 1.54% |
Manganese | 0.11% |
Tungsten | 0.05% |
Molybdenum | 0.04% |
Titanium | 0.02% |
Silicon | Varying amount |
Miscellaneous compounds | Trace amount |
There is no source, and the range in carbon content is too wide to make any sense. This is not steel used for swordmaking. Further, a carbon content of 3% is far too high, and I do not believe the cobalt content either. -- Zz ( talk) 11:20, 2 August 2013 (UTC)
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link)Ok, I took some time to search through my sources. I cannot find the source on the WWII swords. For clarification, to differentiate them from traditionally made swords, the Japanese term for factory -made swords for military use is "gunto." I'm not sure these need to be detailed in this article.
For traditionally-made swords, Hitach Steel provides a good source for the composition of the raw materials. However, for the composition of the final, refined steel, Dr. Tawara seems to be the foremost expert, but I do not have access to his research. Cyril Smith, on the other hand, did an analysis of his own, on four different swords. The results are arranged by the age of the particular sword, and do not account for local variations in hardenability. These results are as follows:
As you can see, there is little variation in these numbers, and the levels of impurities like silicon and phosphorous is lower than most modern steels. piaskowski also did a study by sectioning a sword, revealing an average of .6 to .8% carbon at the edge and skin, but only .2% at the core.
I hope that helps provide a more accurate chart. This info can be found in the book, The Sword and the Crucible: A History of the metallurgy of European swords up to the 16th century by Alan Williams, page 42--43. I'm not good with charts, so someone else will need to change the numbers. Zaereth ( talk) 00:21, 6 August 2013 (UTC)
Right now the article has
"The high carbon steel, called tamahagane, and the remelted pig iron, called nabe-gane, are combined..."
Followed later by
"The nabe-gane is heated, quenched in water, and then broken into small pieces to help free it from slag. The tamahagane is then forged into a single plate, and the pieces of nabe-gane are piled on top..."
I found this hard to follow. I think that this would be better:
"The pig iron is heated, quenched in water, and then broken into small pieces to help free it from slag. The high carbon steel is then forged into a single plate, and the pieces of pig iron are piled on top..."
This avoids having to go back to a previous paragraph to find out what the Japanese words mean. -- Guy Macon ( talk) 18:44, 22 October 2015 (UTC)
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One of the bullet points of the benefits of folding claims that it homogenizes the steel. I am confident that it is simply NOT TRUE that the layers are compositionally identical. In fact, what I've read directly contradicts this, claiming that the layers ARE of different composition (different ratio of elements). One other thing I didn't see is the difference between Japanese swordsmithing, and of the specific ("traditional") way the katana and similar blades were/are made. It isn't plausible, imho, that every single sword made in Japan - ever - followed the process described here. I suggest a discussion is in order about what this article is really about, which is a specific type (school?) of Japanese swordsmithing. 98.21.221.175 ( talk) 08:51, 6 May 2018 (UTC)
At what point does the blade get its cutting edge and how is it sharpened? Is this part of the 'polishing'? Absolutely no mention is made of this either in this article or the one on polishing which is odd given that the whole purpose of a sword is to support a cutting edge. 212.159.76.165 ( talk) 15:15, 2 December 2019 (UTC)