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Samurai Sword Signatures Guide

READING SAMURAI SWORD SIGNATURES 

The Samurai sword can have a series of markings in the tang(Nakago) area. These markings are known as the signature(MEI). While a large number of swords bear some form of signature, it is important to notice that not all Samurai swords are signed.

Translating the signature found in the Samurai sword can be a challenging task. This section explains the basics of how to decypher the characters.

TYPES OF SIGNATURES

Most of the signatures are carved into the metal itself. In some of the World War Two period swords the markings are painted. Most of the time in red or white paint. Some blades will contain both types of signatures, painted and carved/punched. Additional markings may include arsenal stamps or the Showa (WWII) era stamp.

LOCATION OF THE SAMURAI SWORD SIGNATURES

The Samurai swords are signed in the area known as the tang. The tang is covered by the handle of the sword, which is normally secured to the tang via the use of one or two wooden pegs. Once the pegs are removed the handle comes off easily revealing the signatured.

Swords can be signed in one side or in both sides of the tang.

FORGED SIGNATURES

unfortunatelly some of the signatures in the Samurai sword may be forgeries. The signatures that may be faked are normally those of renouned sword makers. Some of the forgeries may date back to the time when the master sword maker was alive. In other cases the origin is more modern. The forgeries are normally perpetrated by an individual wanting to increase the value of the sword.

INFORMATION PROVIDED BY THE SIGNATURE

The information that can be obtained from interpreting the signature in the Samurai sword includes the following: Date, Swordmaker's name (Master), City in which the sword was made, etc.

Additional stamps in the same area provide the arsenal and period.

SIGNATURE BASICS

The signature is generally composed of 5 or 7 characters. The following section provides a breakdown of each type.

FIVE CHARACTER SIGNATURE

The following is an example of a tamg that has 5 characters in the signature. 

 

Where the five character signature:

HI - Usually Province name
ZEN - Usually Province name
TADA - Usually the title
KUNI - Usually the makers name
SAKU - Usually the makers name


SEVEN CHARACTER SIGNATURE

The following is an example of a tamg that has 7 characters in the signature




TRANSLATING SAMURAI SWORD DATES

Some of the Samurai swords are dated. The dates are found in the tang of the sword. There were different methods that the swordsmith employed to date the blades. Some of them are discussed in this section of the website.

Dates are read from the top down. Dates are most commonly written on one side of the tang while the other side holds the master's signature. However, this is not always the case. there are times when the signature and date are located in the same side of the tang.

The characters employed to write a date consisted of numbers, written in kanji, and the symbols for year, month and day. See the following chart.



Additional characters such as those used to describe the different seasons of the year may have also been added to the date in order to indicate when in the year the sword was produced.

SOUTHERN COURT EXAMPLE

The following is an example of how a sword is dated using the Southern Nengo method. This is a sword from the Showa period, starting in 1926, which covers the WWII period. The dates were based on a period plus the number of years into the period where the sword was made. The date inscriptions on the sword are read from the top down.




The following picture illustrates the Japanese names for the different date components.



The following table provides a list of the different periods for sword making and the year it represents in the Western calendar.


Character Period Name Year   Character Period Name Year   Character Period Name Year
Kosho 1455   Genwa 1615   Meiwa 1764
Choroku 1457   Kwan-Ei 1624   An-Ei 1772
Kwansho 1460   Sho-Ho 1644   Tem-Mei 1781
Bunsho 1466   Keian 1648   Kwansei 1789
O-Nin 1467   Jo-O 1652   Ko-Wa 1801
Bunmei 1469   Meireki 1655   Bunkwa 1804
Cho-Ko 1487   Manji 1658   Bunsei 1818
Entoku 1489   Kwanbun 1661   Tempo 1830
Mei-O 1492   Em-Po 1673   Ko-Kwa 1844
Bunki 1501   Tenwa 1681   Ka-Ei 1848
Eisho 1504   Jo-Ko 1684   Ansei 1854
Dai-Ei 1521   Genroku 1688   Man-En 1860
Ko-Roku 1528   Ho-Ei 1704   Bunkyu 1861
Tembun 1532   Shotoku 1711   Genji 1864
Ko-Ji 1555   Ko-Ho 1716   kei-O 1865
Eiroku 1558   Gembun 1736   Meiji 1868
Genki 1570   Kwanpo 1741   Taisho 1912
Tensho 1573   En-Ko 1744   Showa 1926
Bunroku 1592   Kwanen 1748   Heisei 1989
Keicho 1596   Horeki 1751  


ARSENAL MARKING

Here are some examples of the arsenal markings stamped in the tang. The stamp shown on the left photo was placed on the spine area. The stamp shown on the right photo was placed at the base of the tang.



PAINTED MARKINGS

As discussed earlier, there are times when the sword has engraved and painted markings. These are usually either production markings from the factory or arsenal markings. The following is an example of such case.




ADDITIONAL CHARACTERS IN THE SIGNATURE

There are examples where more characters than normally expected are found. The signed tang featured here is one of those instances. One side of the tang has been marked primarily with date related information. The upper section of the inscription refers to the 2,604th year from the foundation of the empire. It was common for the Japanese to refer to years in terms where you had to add two numbers to come up with the proper date.


The other side of the tang includes a small saying: "I gladly give my life". Probably a refernce to the willingness of the soldier to commit to battle until death. The next section of the signature bears the name of the maker. What is interesting to note is that "Ikansai" was actually the middle name of the maker. However, it appears that in this case is being used as a first name. His last name was "Kunimori".
The entire set of characters basically states that Kunimori was a resident of Tokyo and he made the sword.



source: quanonline.com

Japanese Sword Tamahagane Making Process


Traditional methods of preparing a kind of steel called tamahagane used for the Japanese sword by tatara system and procedure of making the sword are briefly introduced with the discussions from the viewpoint of metallurgy and thermo-mechanical processing. Such traditional methods are also revealed to be consistent with the modern science and technology. The quenching process applied to the final stage of the procedure is focused to explain how the pattern of blade, the deformation and residual stresses are induced by the computer simulation based on the theory of metallo-thermo-mechanics relevant to the coupled fields among temperature, micro structural change and stress/strain.

1. Introduction

The Japanese sword originally used as fighting weapon is now one of typical traditional crafts with artistic characteristics, and so many monographs have been published in English [1-6] as well as in Japanese. The sword is also interesting from the viewpoint of modern science and technology [7-26] since the way of manufacturing the sword is really consistent with the science as is same as other surviving traditional products. Tawara, a professor of Japanese Sword Research Laboratory, the University of Tokyo, accomplished a monumental work in the framework of metallurgy[10]. Tawara measured the distribution of carbon density, precipitation and hardness in the cross section of the swords in relation with the pattern of blade and sori representing the mode of deformation during quenching. Successive works were made by Bain [7], Suzuki[11-12], Tsuwa[13], and others.
Very few works on the sword were made, however, from mechanical engineering aspect. Ishikawa[14-16] discussed the mechanism of cutting objects from theory of cutting and the shape of the sword from dynamics, and stress/deformation analysis after quenching by the finite element method was carried out by Fujiwara and Hanabusa[17-18] and the present authors[19-26].

As is well known, the Japanese sword is normally made of a traditional Japanese steel made of iron sand, called tamahagane[27-31], and manufactured by a special way, especially by folding the steel.In the first and second parts of the paper, the process of preparing the steel and the way of making the sword are briefly introduced.
One of the most attractive and important stage of manufacturing the sword applied to the end of the process before grinding and polishing is quenching, which induces the characteristic deformation pattern of bending called sori, and the formation of blade. The following parts treat some results of computer simulation of interesting bent shape of the sword and pattern of the blade simulated by a developed code 'HEARTS' [32-35].
The code was accomplished based on the theory of metallo-thermo-mechanics[36-39] relevant to describing the fundamental equations considering the coupling effect among microstructural change, temperature and stress/strain, which have been applied to the simulation of heat treatment processes considering phase transformation including quenching of the sword[19-26]. After discussing an paradoxical characteristics on the heat transfer coefficient between heated steel covered by a kind of thermally insulated clay, called yakibatsuchi, and water as the coolant, some results of simulation of a sword in the quenching process are presented.
2. PREPARATION OF TRADITIONAL JAPANESE STEEL
 
Almost all Japanese swords with some exceptions are made of tamahagane steel, or noble steel, specially prepared by the tatara system by use of iron sand, but not by normal ore as seen in the old painting.

Fig.1 Old painting of tatara system.

Steels distributed in Japan before Meiji renovation in 1868 were produced by this method, while modern system of iron and steel making had been developed in Europe. The amount of yearly production in the time was approximately 10,000 tons being equivalent to that of Great Britain[40]. 
The steel was used not only for swords, but also for guns, cutting tools, nails for construction of old temples and shrines, and other products necessary for ordinary life.Around the period, the tatara system was replaced by the modern western system except for providing the steel to sword smiths.  
The Iron and Steel Institute of Japan constructed an experimental system of Tatara in [27-28]in Sugaya, Shimane Prefecture, and accumulated interesting data of steel making technology. 
Due to the lack of the steel for the sword, the Japanese Sword Museum, Nippon Bijutsu Token Hozon Kyokai, started to organize the tatara system in Torigami, Shimane Prefecture, under the cooperation with Hitachi Metals, Ltd. in 1977, and provides the steel of 3-4 tons every year.
Iron sand with 2-5\% content of iron mined from Chugoku Mountains, which includes the best quality of iron sand in Japan, concentrated to the degree of 60\% by magnets system, while the mineral dressing method by gravity classification in flowing river had been adopted, which is no more popular to prevent water pollution problem. Such enriched iron sand (masa satetsu) contains 8\% of pure iron Fe and iron oxide Fe2O3 with very small amount of impurity such as 0.026% phosphorus P and 0.002% sulfur S being injurious for carbon steels. Chemical compositions are shown in Table 1. Here, alumina Al2O3 is so rare to be beneficial for low temperature refinement to be stated later.

Table 1 An example of chemical composition of iron sand in virgin and enriched states. 

The enriched iron sand is supplied alternatively to the furnace with charcoal by hands. Figure 2 illustrates the cross sectional view of the furnace under operation with some drainage mechanism constructed to three meters under the ground. Only a difference of the system from the classical one in Fig.1 is that electric motors are used for intermittent air blowing instead of manpowered bellows.

Fig.2 Cross sectional view of tatara furnace

Continuous burning is operated for 70h under the direction of a murage, or chief foreman. The temperature in the furnace is around 1200-1500 deg C lower than the melting point of the steel, which follows that the reduction process of the partly molten state is occurred between iron oxide Fe2O3 and silica SiO2 contained in the clay of furnace. During the process, the initial thickness of 200-400mm of the furnace is reduced to 50-100mm. After taking out the slag from the bottom of the furnace followed by destroying the furnace, a block of blister steel called kera in sponge state with dimension of 2.7m in length, 1m in width and 200-300mm in thickness and with 2-2.5ton containing steel of 1.5-1.8ton is obtained (see Fig.3), while necessary amount of iron sand and charcoal are respectively 8 and 13tons. (It is amazing that the block costs hundred thousand dollars, two hundred times much expensive of normal steel!)

Fig.3 Kera, a block of blister steel.
Steel produced on the both side of the block, where the enough deoxidization is completed by air supplied from kirokan (special wooden pipes) is called tamahagane, or noble steel, which is spelled as mother of metal in Japanese character. Other parts of the block with different chemical composition in Table 2 are also used for the sword making.

Table 2. Chemical composition of tamahagane, forged and core steels.
The chemical compositions of the best part of steel are 1.0-1.4% C, 0.02-0.03% P, 0.006% S, and 0.003-0.004% Ti, being very rare of sulfur and phosphorus even compared with industrial carbon steel (see Table 2).
The steel is cooled by cold environment since the operation is carried out in mid-winter followed by shattering, and distributed to about 300 professional and registered sword smiths in Japan.
 
3. MANUFACTURING OF JAPANESE SWORD

The pieces of the steel with different carbon contents are heated in the carburizing or decarburizing environment, termed jigane-oroshi. This process is made in the furnace burnt by charcoal and ash of rice straws with the blowing air sent by fuigo (blowers). Decarbonization occurs in the part closed to the blower, while CO2 gas accelerates the sintering on the upper parts.
The successive process of making a sword is illustrated in Fig.4. The smith makes a flat plate with a handle termed as tekoita, on which the small pieces of broken flat pieces are piled up covered by a special Japanese paper dampened by water containing clay and rice straws to prevent oxidation on the surface of steel by insulating air. It is known that SiO2 in the clay contributes to increase the impurities including in the slag.

Fig.4 Process of manufacturing the Japanese sword.


Forging process is followed to obtain a block, where about ten to fifteen rounds folding called orikaeshi are repeated to get laminated materials with approximately 1,000 (=2**10) to 30,000 (=2**15) layers. The characteristic pattern of the laminated layers depending on the way of smiths is visible on the surface of the sword, some of which are depicted in Fig.5.

Fig.5 Laminated layers by orikaeshi forging.

Such bonding of each layers during orikaesi process is enhanced by the mechanism of so called mechanical alloying, for which so clean surface of the layers are necessary. This is achieved by dispersing impurities such as oxides and so on with sparks by hammering. The weight of the block decreases during the process to approximately 700-100g in the final shape of the sword.
A bar of shingane (core steel) with low carbon content is wrapped by kawagane or hagane (skin steel) with high carbon for which the tamahagane steel is normally used (see the cross sectional views in Fig.4). This process is called tsukurikomi. After rough grinding by the smith himself, the sword is transferred to the final process of yakiire (quenching), which is the main topics of numerical simulation in the following sections.
Before quenching, a kind of clay, yakiba-tsuchi, mixed by charcoal powder and so on is pasted on the surface of the blade to control the heat transfer intensity to be discussed in Sec.6 as presented in Fig.6.

Fig.6 Tsuchioki, pasting a kind of mixed clay on the blade.

Most interesting situation is that the pasted clay is thick on the ridge while thin on the blade part as illustrated in Fig.7 . Finally the quenching operation of the sword heated up to 800-850 degC into water is carried out. (The temperature of heated sword and cooling water depends on the school of smiths and the material property as well as the dimension of the sword.)

Fig.7 Pasted pattern of the thickness of yakiba-tsuchi

During the quenching process, a white hard part with martensite structure is induced near the blade, while other shining part remains pearlite and ferrite structures. The border of the parts is called hamon as seen in Fig.8.

Fig.8 Hamon, shape of border between quenched and unquenched parts.

Here, wavy or zigzag pattern of the hamon is realized by cutting the clay by a spatulas. A computer simulation how the hamon appears and how the stresses are induced will be treated in the following sections.
4. SUMMARY OF MEATALLO-THERMO-MECHANICS
In such cases of quenching of the Japanese sword, and other machine parts in general, incorporated with phase transformation, fields of metallic structure, temperature and stress/deformation are coupled each other as schematically illustrated in the diagram of Fig.9 [36-39].

Fig.9 Coupling effect among metallic structures, temperature and stress/deformation.

Each field is to be described by the coupled fundamental equations of kinetics of phase transformation, heat conduction equation and constitutive equation combined with kinematic relation and equation of motion, which are summarized in separate page (see separate page of
 
 
5. FRAMEWORK OF DEVELOPED CAE SYSTEM ''HEARTS''

 
Brief introduction of the developed CAE system 'HEARTS' is presented in this section to be used for the simulation of the quenching process of the Japanese sword.
 
+++++ 5.1. Finite Element Scheme and Method of Numerical Calculation ++++
 
Finite element scheme is applied to the fundamental equations developed above, and a new version 2.0 of 'HEARTS' [35] approximately with 35,000 steps consisted of 250 subroutines in several levels is coded by FORTRAN 77. For three dimensional problem as well as two dimensional and axisymmetrical problems (plane stress and strain problems including that of generalized plane strain for stress analysis), which were available in the version 1.0. The 2-D and 3-D isoparametric elements with variable-number-nodes are selected from an element library.
 
A skyline scheme and modified or full Newton-Raphson method are employed to solve these nonlinear equations in each time step. In order to treat unsteady heat conduction equation depending on time, a numerical time integration scheme 'step-by-step time integration method' is introduced, while an incremental method is used for deformation and stress analysis.
 
++++++++ 5.2. Architecture of 'HEARTS' ++++++++
 
The heat treatment simulation code ''HEARTS'' is utilized in the CAE circumstance as illustrated in Fig.10 \ref{Architecture}, being combined with the solver, and pre/post processor such as PATRAN, I-DEAS, or other popularly used processors, and the interface. The data necessary for the simulation is generated by the pre-processor, is output in the form of intermediate file. The data in the file is transferred into the data file for control and initial-boundary conditions as well as the file for the element and node data, while the material data file is constructed separately.

Fig. 10 System architecture of CAE system 'HEARTS'

 
The solver of ''HEARTS'' is divided mainly into four parts corresponding to the equations, and they can be connected by the user's requirement what kind of solutions, coupled or uncoupled, to be solved. The output of the numerical results calculated by the solver are transferred into the files for post-treatment, list image and final results. The data for post-treatment is again stored in the intermediate file through the interface to convert into the final data for post-processor, and several kinds of illustration are available by the user's requirement.
 
6. IDENTIFICATION OF HEAT TRANSFER COEFFICIENT
 
Before quenching the sword into water, the yakiba-tsuchi clay is pasted on the surface as shown in Fig.6 to control the cooling condition of the surface of the steel. Since the temperature distribution is to be calculated in the body of the sword, it is necessary to identify the relative heat transfer coefficient on the metal surface as the function of the thickness of the clay.
 
Series of experiments based on Japan Industrial Standard, JIS-K2242, were made to measure the cooling curve of a cylinder made of silver coated by the clay with different thickness. The reason of the usage of a silver is that the material is not undergone any phase transformation during the heating and cooling process. A thermocouple is mounted on the surface as shown in Fig.11. The cylinder is heated up to 800 degC by a reflection type electric furnace, and cooled in the water.

Fig. 11 A silver rod mounting a thermocouple

 
Obtained cooling curves are demonstrated in Fig.12 as the parameter of thickness of the pasted clay[43]. It is so interesting that the curves for thick clay (t=0.7-0.8 and 0.75-0.9mm) show typical mode with moderate cooling rate due to film boiling followed by severe cooling stage by nuclear boiling, the shape of which are similar to the case without the clay. When the thickness is small (t=0.1-0.15 and 0.2-0.3mm), on the other hand, no film boiling stage is observed, which means that the cylinder is cooled severely from the beginning. This is also confirmed by the observation of bubble nucleation by video camera.

Fig. 12 Cooling curves on the surface of a silver rod depending on the thickness of pasted clay.

Inverse calculation is carried out by perturbation method to identify the heat transfer coefficient on the surface of the cylinder. Results are represented in Fig.13. It is paradoxes to be noted from this figure that the coefficient in the case with thin clay gives higher value than without clay during 800-400 degC being most important temperature range for quenching. This data will be employed as the boundary condition when solving the coupled heat conduction equation.

Fig. 13 Temperature dependent heat transfer coefficient.

 
7. SIMULATED RESULTS OF QUENCHING PROCESS
 
7.1. A Sword Treated and the Condition of Simulation
 
The shape and dimension of the sword treated here is illustrated in Fig.14, which is a model of a classical and famous sword termed Bizen-Osafune. 

Fig. 14. Shape and dimension of a sword treated.


Three dimensional finite element mesh division of the sword is represented in Fig.15, where the division is made for a half part in the width direction due to symmetry. Figures 15(a) and (b) respectively denote the whole region and the enlarged part near kissaki(tip).

(a)Global view.

(b)Near the tip.

Fig. 15. Finit element mesh.

 
Total number of the elements is 828, and that of the nodes is 1230. This model is supposed to consist of two regions, (see Fig.16(a)), core steel with 0.2\% carbon content and skin steel with 0.65%C to which different material data are applied. To differentiate the relative heat transfer coefficient depending on the thickness of the yakibatsuchi clay, the surface of the sword is divided into two parts shown in Fig.16(b) with different value indicated in Fig.13.

Fig. 16 Division of the sword for two materials with different carbon content (a) and for two kinds of surface area with different heat transfer coefficient (b).


 
The sword is uniformly heated up to 850 degC, at which temperature the whole region is changed into austenitic structure, and the sword is quenched into the water of 40 degC.
 
7.2. Effect of Pasted Clay on the Formation of Quenched and Unquenched Border
 
To know the effect of the thickness of clay on the induced hamon (border between quenched and unquenched regions), simulation of quenching under several different conditions were carried out. Red parts of Fig.17 show the volume fractions of martensite after quenching for different way of pasted clay. When the sword is quenched by pasting thick clay of 0.8mm, martensite hardly appear except for the part near the blade (see Fig.17(a)), which follows that very thin hamon occurs. However, almost whole region become martensite as seen in Fig.(b) when thin clay with 0.1mm thickness is pasted on the whole surface. If the clay is pasted thin on the blade side, and thick on other part, on the other hand, ideal distribution of martensite is obtained by the simulation with hardened blade by martensite and with ductile main body by pearlite as is so realistic as the normal sword. Hereafter, the simulation below is made with the pasted yakibatsuchi clay of the final pattern.

Fig. 17 Martensite fraction corresponding to hamon, depending on the way of thickness of 

pasted clay.


 
7.3. Variation of Temperature, Metallic Structures, and Associated Deformation
Figure 18 shows the temperature distribution of the sword with successive time from the beginning of the quenching, and the mode of deformation is also depicted in the figure. The part of blade near the edge with thin thickness shrinks due to thermal contraction by severe cooing, which leads to the bending to the downward termed as gyaku-sori or reverse bending at t=1s as is shown in Fig.(b).

Fig.18 Successive deformation associated with temperature distribution.

 
When martensitic transformation starts to occur in that part, however, normal bending called sori to the upper direction is observed due to the volumetric dilatation by martensite formation (see Fig.(c)). Gyaku-sori again appears at t=3-4s, because of the pearlitic transformation in the part of ridge. In the successive stage of cooling, hot ridge side shrinks gradually because of thermal contraction, and finally, the normal bending can be obtained.
 
Thus simulated deformation gives the good agreement with the actual bending mode of sori. Such mode of successive deformation due to martensitic and pearlitic transformation is shown in Fig.19.

Fig. 19 Successive development of structures


 
7.4. Stress Distribution and Residual Stresses
 
Stress distribution in the longitudinal direction in the course of quenching is represented in Fig.20

Fig. 20 Longitudinal stress distribution and residual stresses.


The simulated residual stresses after complete cooling are compared with measured data by X-ray diffraction technique on the lines along Hasaki (edge), Shinogi (side ridge) and Mune (ridge)(see Fig.14) as shown in Fig.21.

Fig. 21 Comparison of calculated residual stresses with experimental data.

 
It is also noted that the maximum stress near the top of the sword during quenching reaches the fracture stress, which sometimes leads to cracking or breakage of the sword during the operation.
 
8. CONCLUDING REMARKS
Procedure of preparing the traditional Japanese steel, tamahagane, followed by the method of making the Japanese sword is summarized in the first part of the paper from the scientific point of view. Theory of metallo-thermo-mechanics relevant to the simulation of quenching processes and the brief introduction of the finite element computer code 'HEARTS' are also stated.
 
As an example of the application of the simulation of quenching processes, a Japanese sword is focussed, and the change in temperature, metallic structure and stress/deformation are calculated. The results reveal to represent such real situations. The discussion from the viewpoints of metallurgy and mechanics are carried out in each section of preparing Japanese steel and manufacturing the sword, especially on the effect of pasted clay.
 
In conclusion, the technology surviving for over thousand years is really consistent with the modern science and technology.
 
 
Acknowledgements
 
The author wish to express his hearty acknowledgement to Prof. K. Ishikawa, Kanazawa Institute of Technology, Mr. J. Nozaki, Metal Museum, Mr. T. Suzuki, Nippon Bijutsu Token Hozon Kyokai, for their providing instructive information on the science of Japanese sword. Cooperation to develop the CAE system ''HEARTS'' and identify the heat transfer coefficient are made respectively by Mr. K. Arimoto, CRC Research Institute (now moved to SFTC Co.) and Mr. H. Kanamori and co-workers, Idemitsu Kosan Co., respectively. The numerical calculations by use of the system are carried out by Mr. T. Uehara and Mr. H. Ikuta, graduate students of Kyoto University.
 
 
*********** References ***********
 
1. L. Kapp, H. Kapp and Y. Yoshimura, The Craft of the Japanese Sword, Kodansha International, Tokyo (1987).
2. S. Kanzan (Translated by J. Earle), The Japanese Sword --- A Comprehensive Guide, Kodansha International, Tokyo (1983).
3. J. M. Yumoto, The Samurai Sword --- A Handbook, Charles E. Tuttle Co., Tokyo (1991).
4. N. Ogasawara (Translated by D. Kenny), Japanese Swords, Hoikusha, Tokyo (1991).
5. Museum of Fine Arts, Boston (ed.), Japanese Master Swordsmith ---The Gassan Tradition, Museum of Fine Arts, Boston, (1989).
6. J. Homma, Japanese Sword --- The National Museum Series, Kogeisha, Tokyo (1949).
7. B. C. Bain,Trans. JISI,26 (1978) 265.
8. H. Tanimura,J. Metals,32 (1980) 63.
9. T. Kato, Bulletin of the Metals Museum, {\bf 26} (1996) 60.
10. K. Tawara, Scientific Research on Japanese Swords (in Japanese), Hitachi-hyoronsha, Tokyo (1953).
11. T. Suzuki, Science on Tatara and Japanese Sword (in Japanese), Yuzankaku, Tokyo (1993).
12. T. Suzuki, Traditional Technology of Making Japanese Swords (in Japanese), Rikougaku-sha, Tokyo (1994).
13. H. Tsuwa, Proc. 3rd Int. Conf. Production Eng. (1979), 365.
14. K. Ishikawa, The Science of Japanese sword (in Japanese), Kanazawa Institute of Technology, Kanazawa (1989).
15. K. Ishikawa, The Science and culture of Japanese sword (in Japanese), Bulletin of Culture Lecture Series, Atsuta Shrine, No.10 (1997).
16. K. Ishikawa, Nippon-Toh (Japanese Sword) --- High-Technology Threading Through History, Lecture Note, Rochester Institute of Technology, Rochester (1993).
17. H. Fujiwara and T. Hanabusa,Research Report, Faculty of Eng., Tokushima Univ.
(in Japanese), {\bf 38} (1993) 1.
18. H. Fujiwara and T. Hanabusa, Proc. 3rd Int. Conf. Residual Stresses,2 (1991) 1537.
19. T. Inoue, Proc. Int. Seminar on Microstructures and Mechanical Properties of New Engineering Materials (1993) 515.
20. T. Inoue, T. Ohmori, T. Hanabusa and H. Fujiwara, Proc. 4th Int. Conf. Residual Stresses (1994) 970.
21. T. Uehara and T. Inoue, J. Soc. Mater. Sci., Japan (in Japanese),44 (1995) 309.
22. T. Inoue and T. Uehara, Proc. Int. Symp. Phase Transformations during the Thermal/Mechanical Processing of Steel (1995) 521.
23. T. Inoue, T. Uehara, H. Ikuta and I. Miyata., Proc. Int. Conf. Materials and Mechanics-97 (1997) 137.
24. T. Inoue, Trans. Japan Soc. Mech. Eng. (in Japanese ),97 (1994) 132.
25. T. Inoue, Boundary (in Japanese),11 (1995) 36.
26. T. Inoue, Materia (in Japanese),135 (1996) 81.
27. Committee on Restoration Project of Tatara Steelmaking System, Restoration of Tatara Steelmaking Process and the Blister Steel (in Japanese), ISIJ-Special Report No. 9 (1970).
28. Y. Matsushita, Proc. Int. Conf. Science and Technology of Iron and Steel, Trans. ISIJ,11 (1971) 212.
29. J. Kozuka, Trans. ISIJ,8 (1968) 36.
30. K. Kubota, Coll. Int. Inst. CNRS, No.538 (1970) 577.
31. K. Horikawa, Bull. Metals Museum,12 (1982) 29.
32. T. Inoue, D. Y. Ju and K. Arimoto, Proc. 1st Int. Conf. Quenching and Control of Distortion (1992) 206.
33. T. Inoue, K. Arimoto and D. Y. Ju, Proc. 3rd Int. Conf. Residual Stresses (1991) 226.
34. T. Inoue, K. Arimoto and D. Y. Ju, Proc. 8th Int. Cong. Heat Treatment of Materials (1992) 569.
35. T. Inoue and K. Arimoto, J. Mater. Eng. and Perfor., ASM,6 (1997) 51.
36. T. Inoue and B. Raniecki, J. Mech. Phys. Solids,26 (1978) 187.
37. T. Inoue, S. Nagaki, T. Kishino and M. Monkawa, Ing.-Archiv.,50(1981) 315.
38. T. Inoue and Z. G. Wang, Mat. Sci. Tech.,1(1985) 845.
39. T. Inoue, Berg-und Huttenmannische Monatshefte,132(1987) 63.
40. T. Kuroiwa, Distance between Tatara and Kouro (in Japanese), Agne, Tokyo (1993).
41. W. A. Johnson and R. F. Mehl, Trans. AIME,135(1939) 416.
42. C. L. Magee, Nucleation of Martensite, ASM, New York (1968).
43. H. Kanamori, E. Nakamura, S. Koyama and T. Inoue,J. Japan Soc. Heat Treatment,36(1997
 
the source of the article: Process of a Japanese Blade

Japanes Samurai Sword Parts of a Katana

Japanese Samurai Sword Hystory

THE HISTORY OF THE SAMURAI SWORD
FROM THE EARLY DAYS TO THE PRESENT
The Samurai sword is unquestionably the most well known sword in the history of the world. Its presence in the batlefield as an astonishing weapon and in the homes of the Samurai warriors beautifully adorning rooms, has been felt for the last 1500 years.

It is believe that it was originally started in China, then the technology moved to Korea and finally ended up in Japan. The development and evolution of the construction and design of the Samurai sword is closely tied to the different periods in Japanese history. As technology and political events unfolded in Japan, the Samurai sword morphed to adapt to the needs of the day.

The biggest challenge of the sword maker is to successfully combine two different qualities of metal. The sword that is borned from this marriage is light, reliable in battle and practical.

The following section provides a comprehensive view of the various periods in Japanese history;
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ANCIENT PERIOD (Before AD 650)

Swords of this period were primarily made by Chinese and Korean masters. There aren't very many examples of these swords around today. This period marks the begining of the Japanese culture under the reign of emperor Jimmu.

The swords from this period were called "Chokuto". Unlike the current version, the blades of these swords had a straight shape. No curvature. It is possible that some of these swords were made in China.

Some of these swords have been found in tombs. Their blades are too thin to be designed for combat. It is likely they were created for ceremonial purposes.

NARA PERIOD (650 to 793)

The first capital city of Japan was established during this period. New laws were introduced and the imperial family established a stronghold. The need for a better equipped army started creating the need for the development of better swords.

HEIAN PERIOD (794 to 1191)

Kyoto became the capital of Japan and was ruled by the Fujirawa clan. This era produced some of the best examples of Samurai swords as new techniques were developed.

Warfare had evolved. Samurai warriors were now fighting from horseback. The old swords were designed for a thrusting motion, the new swords will now require a slashing motion. This required for the sword to have a curvature. In addition, the sword had to be light enough to be hels with a single hand.

The length of the blade was incremented. The cutting edge was around 3 feet in length. The curvature was uniform. The sword was very strong. The warrior would wear the sword slung from the waist with the edge facing down.

The swords from this period are called "Tachi". The hammon was broader. This was the first time that "Ashi" was employed. The Ashi were strips of soft steal positioned in the hardened area of the edge. Designed to protect the blade when swords clashed in combat.

KAMAKURA PERIOD (1192 to 1336)

Feudal Japan is started. The Shogunate form of government is in place. The Mongols attempt to invade Japan and are met by Kamatura warriors who defend the island ferociously. However, their weapons are no match to the Mongol forces and are beaten. Suddenly, typhoon season starts and the mongol ships are destroyed stopping the invasion of Japan.

The Kamakura warriors see the need for better swords and begin working on developing better techniques. Some of the best built swords emerge at this time. The Kamakura period is known as the golden age of the Samurai Sword.

Some of the advancements in sword development include the insertion of a soft core of low carbon steal into the blade. This technique replaced the single piece of high carbon construction employed earlier.

The size of the hardened edge was increased. The blades became broader with a bigger point. The larger hardened area permitted for the sword to be polished multiple times. This is quite an advancement in technology.

As a result of experiences fighting the Mongols, sword makers saw the need for the development of a shorter sword. The reduction in size would make it easier to maneuver in hand to hand combat. This marks the birth of the "Tanto" sword.

The importance of the foot soldier grew during this period. A reflection of this fact is that the "Tachi" required two hands to be used.

Emperor Godaigo gathers up forces and manages to overthrow the Shogunate.
Era Name Year Comments
Kennin 1201
Genkyu 1204
Ken-Ei 1206
Shogen 1207
Kenreki 1211
Kempei 1213
Jokyu 1219
Jo-O 1222
Gennin 1224
Karoku 1225
Antei 1227
Kwangi 1229
Jo-Ei 1232
Tempuku 1233
Bunreki 1234
Katei 1235
Beki-Nin 1238
En-O 1239
Ninji 1240
Kwangen 1243
Ho-Ji 1247
Enchou 1249
Shoka 1257
Era Name Year Comments
Shogen 1259
Bun-O 1260
Kocho 1261
Bun_Ei 1264
Kenji 1275
Ko-An 1278
Sho-O 1288
Sho-An 1299
Kengen 1302
kagen 1303
Tokuji 1306
Enkei 1308
O-Cho 1311
Showa 1312
Bumpo 1317
Gen-O 1319
Genko 1321
Shochu 1324
Kareki 1326
Gentoku 1329
Gen-Ko 1331
Kemmu 1334
Engen 1336

MUROMACHI PERIOD (1337 to 1573)

The Shogunate returns to power. Japan is split in two as civil war erupts. The conflict lasts for over 100 years and causes a huge supply of swords to appear. Lack of materials, the need to outfit armies with swords in a short period of time, constant attacks and other factors contributed to a sharp decline in the quality of the swords.

The constant fighting leads to the development of new technology. This period marks the birth of the "Uchigatana". This is a companion sword measuring roughly 24 inches and designed for single hand use. It was ideal for fighting indoors where the larger "Tachi" was not practical.

Era Name Year Comments
Ko-Koku 1340
Shohei 1346
Kentoku 1370
Bunchu 1372
Tenju 1375
Ko-Wa 1381
Genchu 1384
O-Ei 1394
Shocho 1428
Ei-Ko 1429
Kakitsu 1441
Bun-An 1444
Ho-Toku 1449
Ko-Toku 1452
Kosho 1455
Choroku 1457
Era Name Year Comments
Kwansho 1460
Bunsho 1466
O-Nin 1467
Bunmei 1469
Cho-Ko 1487
Entoku 1489
Mei-O 1492
Bunki 1501
Eisho 1504
Dai-Ei 1521
Ko-Roku 1528
Tembun 1532
Ko-Ji 1555
Eiroku 1558
Genki 1570
Tensho 1573

AZUCHI-MOMOYAMA PERIOD (1574 to 1602)

Japan is reunited under the control of the warrior Toyotomi Hideyoshi. The existing large armies are put to use by invading China and Korea. A decree is issued that prohibits farmers from owning swords.

This period saw the birth of the "Katana". Measuring between 24 to 30 inches in length. A companion sword called the "Wakisashi" was also created. Measuring around 18 inches long. The swords were meant to be worn together. This became an icon and tradition of the Samurai warrior until the end of WWII when the swords were outlawed.

The swords were more appealing to the eye. They were more shiny and had larger hammons. These styles of swords are known as Shinto (meaning "New sword"). As peace spread through the country swords started becoming more an ornament or sign of status rather than a weapon.

Changes in warfare tactics are developed as a result of the introduction of the gun.


Era Name Year Comments
Bunroku 1592
Keicho 1596

EDO PERIOD (1603 to 1867)
Modern day Tokyo becomes the capital of Japan. This is a period of relative peace. Japan's first contact with the west took place during this period with the coming of Commodore Perry in 1853.

The quality of the Shinto blades were an improvement from those created during the warring years. However, this came to an end when shortages of materials, high taxes and corruption placed a heavy toll on the craft. Quality began to suffer again.

A chief swordsmith was appointed. This organization was in charge of issuing certificates to individuals, allowing them to become authorized sword makers. It is thought that this organization contributed to the fall in quality of the swords. They would sell the titles at a very high price. In turn, the sword makers would charge an increased fee for their swords in an effort to recuperate their investment and make some profit.
Nearly 1,000 people purchased the certification. Many of them produced blades at a very quick rate compromising quality. An example is a maker named Tsuda Sukehiro, who produced a total of 1,620 blades during his career.

The 1780's saw a revival of interest in quality. A new type of sword named the "Shishinto" (Meaning New New Sword) was borned. One of the founders of this movement was named Suishinshi Masahide. He traveled the country and trained around 100 sword makers.

In 1876 the Samurai class was abolished. It was illegal to wear swords in public. This marks an end to the classical Samurai sword.

Era Name Year Comments
Genwa 1615
Kwan-Ei 1624
Sho-Ho 1644
Keian 1648
Jo-O 1652
Meireki 1655
Manji 1658
Kwanbun 1661
Em-Po 1673
Tenwa 1681
Jo-Ko 1684
Genroku 1688
Ho-Ei 1704
Shotoku 1711
Ko-Ho 1716
Gembun 1736
Kwanpo 1741
En-Ko 1744
Kwanen 1748
Horeki 1751
Era Name Year Comments
Meiwa 1764
An-Ei 1772
Tem-Mei 1781
Kwansei 1789
Ko-Wa 1801
Bunkwa 1804
Bunsei 1818
Tempo 1830
Ko-Kwa 1844
Ka-Ei 1848
Ansei 1854
Man-En 1860
Bunkyu 1861
Genji 1864
Kei-O 1865

MODERN PERIOD (1868 to now)
Emperor Meiji regained power and moved the capitol to Tokyo. In 1876 he created a law prohibiting anyone from wearing a Samurai sword. The eras included in this period are:

Era Name Year Comments
Ansei 1854
Bunkyu 1861
Genji 1864
Keio 1865
Meiji 1868
Taisho 1912 This era includes swords created during WWI.
Showa 1926 This era includes swords created during WWII.

The WWII Samurai Sword

The Samurai sword had a prominent status during WWII. Just about every member of the Japanese armed forces was either issued a sword or brought their own family sword into combat. The spirit of the Samurai warrior was very present in the minds of the soldiers.

During WWII swords were mass produced for officers in the Imperial Army. These blades were made from foundry steel. The were of very low quality. They did not have a hammon, hardened edge or many of the other characteristics found in hand-made swords.

The Post-WWII Samurai Sword

After the war strict rules were put in place to control the existance of weapons in Japan. These rules also applied to Samurai swords. A family who had a sword which had been handed down from generation to generation could keep ownership. However, the sword had to be registered with the government.

Any of the swords which were mass produced during WWII cannot be registered and must be destroyed.

The manufacturing of swords was completly banned. The restriction in manufacturing and posession was lifted in 1953. However, sword makers were held under rules to ensure that they were producing works of art rather than weapons for war. A list of the rules is included here. They are still in place today.




Rule 1
All swordsmiths must be licensed. to obtain a license the person must serve an apprenticeship under a licensed sword maker for a period no less than five years.

Rule 2
The maximum production of swords from a licensed sword maker is two long swords (over 2 feet) and three small swords (under 2 feet) per month.

Rule 3 All swords must be registered with the police.

Rule 4 Any cutting instrument with a length of under 6 inches, which has no hole in the tang is considered to be a knife an is exempt from these rules.

Japanes Samurai Sword Schools

SAMURAI SWORD SWORDSMITH SCHOOLS
The craft of Samurai sword making has long been considered an art form. Various towns in Japan would have sword makers who would develop their own techniques to treat and shape the steel. The swordmaker would create a "school", where locals from the village could learn the art of sword making.

The techniques of sword manufacturing were well guarded secrets. Having the ability to create light weight swords that had the strength to make it through battles, and hold an edge capable of cutting through armor would make the difference between life and death.

Each school would develop ways in which to marke their creations. Often times this was done by developing a heat temper pattern for the blade and signing the tang.

ANCIENT SWORD PERIOD (Until AD 900)
These swords were made primarily by Chinese and Korean swordmakers. The quality of the steel was not very good. The swords would break during combat. The swords were primarily straight, instead of having the iconic curve look of the traditional Samurai sword.

Some samples of these swords have been found in tombs. Many of them were not very thick, indicating the possibility that they were ceremonial swords instead of combat weapons. 


OLD SWORD PERIOD (900 to 1530)
The following list of schools flourished during the old sword era:

A. BIZEN SCHOOL
B. YAMASHIRO SCHOOL
C. YAMATO SCHOOL
D. SOSHU SCHOOL
E. MINO SCHOOL

The schools were located in different regions of Japan. The characteristics of each sword are partly dictated by the geographical location because of the source of the ore needed to produce the steel for the sword.

Most of the modern swordsmiths produce blades using the Bizen style.

NEW SWORD PERIOD (1530 to 1867)
The following is a list of the provinces and the sword smith's who represent some of the finest expressions of the art generated during this time period:

1. YAMASHIRO PROVINCE
2. SETTSU PROVINCE
3. MINO PROVINCE
4. MUSASHI PROVINCE
5. OMI PROVINCE
6. IWASHIRO PROVINCE
7. RIKUZEN PROVINCE
8. WAKASA PROVINCE
9. ECHIZEN PROVINCE
10.KAGA PROVINCE
11.BITCHU PROVINCE
12.AKI PROVINCE
13.KII PROVINCE
14.BIZEN PROVINCE
15.HIZEN PROVINCE
16.SATSUMA PROVINCE


MODERN SWORD (1868 to now)
It is during these years that Japan begins to open to the rest of the world and modernizes. This period rushed the end of the Samurai era. Swords could no longer be worn and the swordmakers started to vanish.

The Showa era (1926 to now) is considered to be a part of the modern sword period. It is during this time that WWII occurs and helps revive the art of swordmaking. However, it is to no extent comparable to what it once was.

The years after the WWII (1945) marked a very grim period for the art of sword making. Many of the elder swordsmiths died without leaving an apprentice to continue the trade. Many of the students quit under the intense scrutiny of regultions. The country had been defeated and destruction was everywhere.

Swordsmiths today are regulated by a set of rules established in 1953. The rules are set to ensure that the craftsmen produced pieces of art and not weapons of war. The rules are as follows:

Rule 1 All swordsmiths must be licensed. to obtain a license the person must serve an apprenticeship under a licensed sword maker for a period no less than five years.

Rule 2 The maximum production of swords from a licensed sword maker is two long swords (over 2 feet) and three small swords (under 2 feet) per month.

Rule 3 All swords must be registered with the police.

Rule 4 Any cutting instrument with a length of under 6 inches, which has no hole in the tang is considered to be a knife an is exempt from these rules.

The art of sword making in Japan has seen a resurgance. An organization has been formed to preserve the art and sword making and promote the appreciation of the swords. The Nihon Bijutsu Token Hozon Kyokai (The Society for the Preservation of Japanese Art Swords, was founded in 1960 and is headquartered in Tokyo.

The group holds an anual competition where swordsmiths can enter a blade. There is a panel of 15 judges that review the workmanship. The judges come from a variety of trades; swordsmiths, polishers appraisers and others decide the outcome of the contest.