J. Wadsworth, D.R. Lesuer /Materials Characterization 45(2000) 289-313 Also, in 1960, Sir Cyril Stanley Smith [1 6 wrote ely and sword[s]of 60 or 50 refinings(actually 64 that in his opinion: yers)should be expected. The Japanese sword blade is the supreme the prediction was made. A sword of marked metallurgical art. omb in Xuzhou, Jiang-su .. Examination showed Certainly, world wide, the Japanese sword (Nippon that . it consisted of alternative low- and high- to)is one of the most famous of all swords. The sword carbon layers, about 60 in total. The cost of the has always held a special place in the history and marked as worthy of 1500 coins, culture of Japan. Japanese legend, for example, tells us that Susanoo brother of the Sun goddess amater half years"living asu, slew an eight-headed dragon with a single stroke of a sword. Despite this, the blade was deemed inferior 2.5. Merovingian pattern-welded blade and Susanoo was given a magnificent sword from the dragon's tail. He gave the sword to his sister, the Sun An early European technique dating from about Goddess, who then handed to her grandson the Imper the end of the second century resulted in the ial Regalia that included three items-the jewel, the Merovingian patterm-welded blades. (Iron objects mirror, and the sword. manufactured prior to this date are frequently too From a metallurgical viewpoint, the Japanes severely corroded for their surfaces to be evaluated sword is of interest at several different levels. First, metallurgically. According to Smith [16], Merovin- their manufacture involved the solid-state bonding of blades were primarily manufactured on the steels to themselves and to steels of radically different Rhine although they were widespread through trade carbon contents. That is, in its simplest form, with the and war. The blades consisted of strips of pure iron exception of the very earliest blades, the sword is a and carbon steel (or iron strips that had been composite. An example of one of the composite de- carburized on one side) hammered or forged to- signs is that of a high-carbon external sheath surround gether in a manner involving folding or twisting The cutting edge consisted of the high-carbon-con tent steel, often inserted between plates of low- carbon material. Upon grinding to shape after heat yers become visible. In addition, it is quite likely that etching in fruit juice or sour beer was carried out to develop the patterns. An example is given in Fig 3, from a blade discovered in a Viking grave in South Finland [17] Thus, beginning in the period around 500 AD pattern-welded daggers and swords were made, ncluding Viking blades starting in about 600 AD. Smith [16 comments that the edges martensitic between plates of iron in similar to the Japanese sword. He also notes that it is" difficult to justify the particular pattern used in the center of the swords on any but aesthetic grounds. " Included in this group of materials is the carly Japanese sword. 2.6. Japanese sword The Japanese sword has universally been regarded by metallurgists as the ultimate metallurgical accomplishment. For example, in 1962 Edgar C. Bain [19]wrote attern- welded blade discover University [18]. Courtesy of The Gun Report
would probably indicate 32 and 128 layers respectively and sword[s] of 60 or 50 refinings (actually 64 layers) should be expected. This was confirmed by an excavation soon after the prediction was made. A sword of marked 50 refinings dated back to 77 AD was unearthed from a tomb in Xuzhou, Jiang-su...Examination showed that...it consisted of alternative low- and highcarbon layers, about 60 in total. The cost of the sword was also marked as worthy of 1500 coins, equivalent to grains enough for one man's two and half years' living. 2.5. Merovingian pattern-welded blade An early European technique dating from about the end of the second century resulted in the Merovingian pattern-welded blades. (Iron objects manufactured prior to this date are frequently too severely corroded for their surfaces to be evaluated metallurgically.) According to Smith [16], Merovingian blades were primarily manufactured on the Rhine although they were widespread through trade and war. The blades consisted of strips of pure iron and carbon steel (or iron strips that had been carburized on one side) hammered or forged together in a manner involving folding or twisting. The cutting edge consisted of the high-carbon-content steel, often inserted between plates of lowcarbon material. Upon grinding to shape after heat treating, patterns arising from the different layers become visible. In addition, it is quite likely that etching in fruit juice or sour beer was carried out to develop the patterns. An example is given in Fig. 3, from a blade discovered in a Viking grave in South Finland [17]. Thus, beginning in the period around 500 AD, pattern-welded daggers and swords were made, including Viking blades starting in about 600 AD. Smith [16] comments that the edges are martensitic between plates of iron in a manner similar to the Japanese sword. He also notes that it is ``difficult to justify the particular pattern used in the center of the swords on any but aesthetic grounds.'' Included in this group of materials is the early Japanese sword. 2.6. Japanese sword The Japanese sword has universally been regarded by eminent metallurgists as the ultimate expression of metallurgical accomplishment. For example, in 1962, Edgar C. Bain [19] wrote: The old swords of Japan are probably the best examples of the almost incredible pains taken to produce a superb implement. Also, in 1960, Sir Cyril Stanley Smith [16] wrote that in his opinion: The Japanese sword blade is the supreme metallurgical art. Certainly, world wide, the Japanese sword (Nipponto) is one of the most famous of all swords. The sword has always held a special place in the history and culture of Japan. Japanese legend, for example, tells us that Susanoo, brother of the Sun Goddess Amaterasu, slew an eight-headed dragon with a single stroke of a sword. Despite this, the blade was deemed inferior and Susanoo was given a magnificent sword from the dragon's tail. He gave the sword to his sister, the Sun Goddess, who then handed to her grandson the Imperial Regalia that included three items Ð the jewel, the mirror, and the sword. From a metallurgical viewpoint, the Japanese sword is of interest at several different levels. First, their manufacture involved the solid-state bonding of steels to themselves and to steels of radically different carbon contents. That is, in its simplest form, with the exception of the very earliest blades, the sword is a composite. An example of one of the composite designs is that of a high-carbon external sheath surroundFig. 3. Merovingian pattern-welded blade discovered in a Viking grave in the South of Finland. It was most likely made on the Rhine in the period 650 ± 700 AD. Helsinki University [18]. Courtesy of The Gun Report. 294 J. Wadsworth, D.R. Lesuer / Materials Characterization 45 (2000) 289±313
J. Wadsworth, D.R. Lesuer /Materials Characterization 45(2000) 289- 95 ng a low-carbon core. The procedure used to make such a blade is shown in Fig. 4. This composite pproach allowed the swordmaker to achieve the desirable properties of both hardness and ductility in a single weapon. Often, one of these properties is only developed at the expense of the other. Tool steel econd, to produce the high-carbon part of the blade, the steel was subjected to multiple folding perations; this has given rise to the erroneous con- 5 cept that the swords contain millions of discrete layers. Thi experimentally examined in next section on modern lmcs Third, the development of the complex and Hardened beautiful surface markings was a consequence a selective surface heat-treatment process(known as yaki-ire), achieved in part by covering the blade with different thicknesses of clay; this gave rise to an intriguing combination of transformation pro- ducts and surface patterns. This was not only visible and aesthetic example of the skill of the (ultrahigh carbon steel) swordmaker, but it was also evidence that the edge of the blade had been hardened Fig. 4. Procedure used by Japanese blacksmiths to make The blade must have a recognizable pattern, called laminated tools by solid-state bonding ultrahigh carbon the hamon, where the structure changes from the hard steel, known as kawagane, to soft iron; including a cross martensite at the edge, called akiba, to soft pearlite section of a blade coated with various thicknesses of clay to The hamon is perhaps the most important aesthetic control temperature, with minimal clay coat at the edge to allow proper hardening(adapted from Bain [19)[14] feature of a blade, and the first thing sword aficiona dos look for, as it is essentially the swordsmiths signature. Kapp et al. [21] cite the work of B w. stage of manufacture of the Japanese sword in which Robinsons classic book The Arts of the Japanese steel of about 1.8%C is used Sword [22], illustrating 53 different hamon, each with The high-carbon steel (called kawagane, but also its own name(from the descriptive"straight irreg sometimes called magane)used for blademaking wa lar"to the more suggestive "chrysanthemum and principally prepared using a reduction process meth- water") and the name of the smith or school with od, in which iron, sand, and charcoal produced tama- which it is identified. (See Fig. 5 for an illustration of hagane. A fixed amount of iron ore and charcoal was broad classes of hamon patterns mixed and heated in air to 1200C. resulting in The Japanese swords external sheath has a similar products of molten pig iron, slag, and unmelted carbon content (i.e, it can be hypereutectoid, about ultrahigh-carbon steel (UHCS). The iron ore came 0.8-1%C)to that of the Damascus sword (also from so-called black sands known as satetsu(iron hypereutectoid, but in the 1.5-1.8%C range). This oxide). The carbon was added to the black sand in a similarity of composition is especially so in the early smelter called a tatara. When the pig iron and sla were allowed to separate by pouring, the end product was lumps of UHCS containing about 1.7%C(tama i Tylecote[20] has pointed out a similarity in this hagane). This material was then repeatedly forged regard between the Japanese sword composite design and folded until the appropriate shape and reduction and the much later development of"shear steel"in in carbon content was achieved through decarburiza Western Europe following the Industrial Revolution. tion. (It should be noted that, depending upon the The similarity lies in the fact that comparatively few arbon additions, temperature, and time at tempera- pieces of steel of different carbon content wer welded together to make a composite, single-edged, ture, the result of such a repeated folding and forgin blade which was finally heat treated. In shear steel process could be low-carbon steel. mild steel outer strips encased a high-carbon center blade involved a number trip-a design currently available in handmade First, the tama-hagane was repeatedly forged and knives by contemporary artisans. In fact, Tylecot folded to produce the kawagane, which becomes the goes as far as to say, "There is essentially no sheath or jacket steel. Second, the shingane, or low- difference in principle between a scythe [made from carbon core steel, was formed, also by a repeated shear steel], and a Japanese sword. folding procedure. Third, the low-carbon core was
ing a low-carbon core. The procedure used to make such a blade is shown in Fig. 4. This composite approach allowed the swordmaker to achieve the desirable properties of both hardness and ductility in a single weapon.1 Often, one of these properties is only developed at the expense of the other. Second, to produce the high-carbon part of the blade, the steel was subjected to multiple folding operations; this has given rise to the erroneous concept that the swords contain millions of discrete layers. This point is experimentally examined in the next section on Modern LMCs. Third, the development of the complex and beautiful surface markings was a consequence of a selective surface heat-treatment process (known as yaki-ire), achieved in part by covering the blade with different thicknesses of clay; this gave rise to an intriguing combination of transformation products and surface patterns. This was not only a visible and aesthetic example of the skill of the swordmaker, but it was also evidence that the edge of the blade had been hardened. The blade must have a recognizable pattern, called the hamon, where the structure changes from the hard martensite at the edge, called yakiba, to soft pearlite. The hamon is perhaps the most important aesthetic feature of a blade, and the first thing sword aficionados look for, as it is essentially the swordsmith's signature. Kapp et al. [21] cite the work of B.W. Robinson's classic book The Arts of the Japanese Sword [22], illustrating 53 different hamon, each with its own name (from the descriptive ``straight irregular'' to the more suggestive ``chrysanthemum and water'') and the name of the smith or school with which it is identified. (See Fig. 5 for an illustration of broad classes of hamon patterns.) The Japanese sword's external sheath has a similar carbon content (i.e., it can be hypereutectoid, about 0.8 ± 1% C) to that of the Damascus sword (also hypereutectoid, but in the 1.5 ± 1.8% C range). This similarity of composition is especially so in the early stage of manufacture of the Japanese sword in which steel of about 1.8% C is used. The high-carbon steel (called kawagane, but also sometimes called uagane) used for blademaking was principally prepared using a reduction process method, in which iron, sand, and charcoal produced tamahagane. A fixed amount of iron ore and charcoal was mixed and heated in air to 1200°C, resulting in products of molten pig iron, slag, and unmelted ultrahigh-carbon steel (UHCS). The iron ore came from so-called black sands known as satetsu (iron oxide). The carbon was added to the black sand in a smelter called a tatara. When the pig iron and slag were allowed to separate by pouring, the end product was lumps of UHCS containing about 1.7% C (tamahagane). This material was then repeatedly forged and folded until the appropriate shape and reduction in carbon content was achieved through decarburization. (It should be noted that, depending upon the carbon additions, temperature, and time at temperature, the result of such a repeated folding and forging process could be low-carbon steel.) Forging the blade involved a number of steps. First, the tama-hagane was repeatedly forged and folded to produce the kawagane, which becomes the sheath or jacket steel. Second, the shingane, or lowcarbon core steel, was formed, also by a repeated folding procedure. Third, the low-carbon core was Fig. 4. Procedure used by Japanese blacksmiths to make laminated tools by solid-state bonding ultrahigh carbon steel, known as kawagane, to soft iron; including a cross section of a blade coated with various thicknesses of clay to control temperature, with minimal clay coat at the edge to allow proper hardening (adapted from Bain [19]) [14]. 1 Tylecote [20] has pointed out a similarity in this regard between the Japanese sword composite design and the much later development of ``shear steel'' in Western Europe following the Industrial Revolution. The similarity lies in the fact that comparatively few pieces of steel of different carbon content were welded together to make a composite, single-edged, blade which was finally heat treated. In shear steel, mild steel outer strips encased a high-carbon center stripÐ a design currently available in handmade knives by contemporary artisans. In fact, Tylecote goes as far as to say, ``There is essentially no difference in principle between a scythe [made from shear steel], and a Japanese sword.'' J. Wadsworth, D.R. Lesuer / Materials Characterization 45 (2000) 289±313 295
J. Wadsworth, D.R. Lesuer /Materials Characterization 45(2000) 289-313 Kanehira and the dojigiri by Yasutsuna made over 900 years ago. Photographs of the o-kanehira are shown in Fig.6. 2.7. Medieval damascened knive Piaskowski [24 has reviewed in detail pat sugita komidare welded damascened knives found in Poland dating from the Sth to 12th century. Their real origin is not clear. but Piaskowski believes that some of the knives may be examples of the work of early medieval Polish smiths. The knives all consisted of three regions: a steel cutting edge, adjacent to a complex, central, patterned layered region of carbur ized iron and iron, and a backing layer of iron or itatstrra steel. This is in contrast to other related techniques in which a steel central layer is sandwiched between pattemed layers of iron and steel. Evidence for heat Fig. 5. Types of Hamon(after Sato [23]). treatment to produce martensitic structures, and tempered structures, is described. Techniques invol ving from 3 to 17 initial layers are presented. In all inserted, by one of several methods, inside the high- cases, hammer welding and plastic deformation took carbon jacket steel. In the fourth step, the composite place during manufacture. The carbon contents of the was drawn out to the approximate length of the blade, composition, 0.5%C, is given for one steel in one of layers are poorly evaluated, however, and only one and the fifth step shaped the final blade. The end product is a kawagane steel with the knives excellent mechanical properties because the carbon content is both relatively low(about 0.6-1.0% C) and the carbides are distributed uniformly fine-grained matrix. As discussed later, no visible pattern-welded structure is obtained from this scale of folding, not only because the individual, 0.2-m layers are unresolvable to the naked eye, but also because the carbon content of each layer is iden- cal(carbon atoms diffuse a distance of 1. 4 um in 30 s at 1000C). An observable pattern-welded tructure. however often emerges from the final several folds Thus the method of manufacture and the of the surface patterns on the Japanese sword are quite different from those of Damascus swords Specifically, the principal surface pattem on a Japa nese sword is created as a result of the variou transformation products following heat treatment the blade. There are also surface pattems that consist of a gross texture from the final stages of piling folding, and forging. The earliest reference to sur- face patterns on a Japanese sword, referenced by Smith [161, is to 1065 AD. There are subtleties to these patterns that illustrate several intriguing me- There are an estimated 1 million swords now own to exist; 117 have been designated as Japa- 6.“O- Kanehira” achi by Ka nese national treasures. The most famous and rev- 9.2 cm. Mid-Heian period, approximately 1000 AD ered of the swords are identified with a name o National Museum. Signed Bizen no kuni Kanehira . Tokyo hira of Bizen providence").(After Sato [23])
inserted, by one of several methods, inside the highcarbon jacket steel. In the fourth step, the composite was drawn out to the approximate length of the blade; and the fifth step shaped the final blade. The end product is a kawagane steel with excellent mechanical properties because the carbon content is both relatively low (about 0.6 ± 1.0% C), and the carbides are distributed uniformly in a fine-grained matrix. As discussed later, no visible pattern-welded structure is obtained from this scale of folding, not only because the individual, 0.2-mm layers are unresolvable to the naked eye, but also because the carbon content of each layer is identical (carbon atoms diffuse a distance of 1.4 mm in 30 s at 1000°C). An observable pattern-welded structure, however, often emerges from the final several folds. Thus, the method of manufacture and the origins of the surface patterns on the Japanese sword are quite different from those of Damascus swords. Specifically, the principal surface pattern on a Japanese sword is created as a result of the various transformation products following heat treatment of the blade. There are also surface patterns that consist of a gross texture from the final stages of piling, folding, and forging. The earliest reference to surface patterns on a Japanese sword, referenced by Smith [16], is to 1065 AD. There are subtleties to these patterns that illustrate several intriguing metallurgical issues. There are an estimated 1 million swords now known to exist; 117 have been designated as Japanese national treasures. The most famous and revered of the swords are identified with a name or meito. Two such examples are the o-kanehira by Kanehira and the dojigiri by Yasutsuna made over 900 years ago. Photographs of the o-kanehira are shown in Fig. 6. 2.7. Medieval damascened knives Piaskowski [24] has reviewed in detail patternwelded damascened knives found in Poland dating from the 8th to 12th century. Their real origin is not clear, but Piaskowski believes that some of the knives may be examples of the work of early medieval Polish smiths. The knives all consisted of three regions: a steel cutting edge, adjacent to a complex, central, patterned layered region of carburized iron and iron, and a backing layer of iron or steel. This is in contrast to other related techniques in which a steel central layer is sandwiched between patterned layers of iron and steel. Evidence for heat treatment to produce martensitic structures, and even tempered structures, is described. Techniques involving from 3 to 17 initial layers are presented. In all cases, hammer welding and plastic deformation took place during manufacture. The carbon contents of the layers are poorly evaluated, however, and only one composition, 0.5% C, is given for one steel in one of the knives. Fig. 5. Types of Hamon (after Sato [23]). Fig. 6. ``O-Kanehira.'' Tachi by Kanehira. Steel. Nagasa 89.2 cm. Mid-Heian period, approximately 1000 AD. Tokyo National Museum. Signed Bizen no kuni Kanehira (``Kanehira of Bizen providence''). (After Sato [23]). 296 J. Wadsworth, D.R. Lesuer / Materials Characterization 45 (2000) 289±313
J. Wadsworth, D.R. Lesuer /Materials Characterization 45(2000) 289-313 2.8 Thailand axes and tools prepared by the smith Although less extensively developed than the by cementation, ie burying a thin strip of Indonesian metal kisses (next section). there are low-carbon iron about 1 mm thick in a charcoal fire interesting artifacts originating in Thailand. In a study with limited air access to give a reducing atmo- of such objects [25], four iron artifacts were exca sphere, rich in carbon monoxide. vated in Northeast Thailand and three were dated to 2.9 Indonesian kris the Late Iron Age(e.g, 300-400 AD). The fourth artifact, dated by association with the other three, involved welding an ultrahigh carbon content steel The Indonesians of Java and other Malayan onto a wrought iron core to form a high quality axe Islands made a number of knives known as kisses blade. In concluding that the artifacts date to the late Indonesian kisses usually are forged to have re. Iron Age, the authors note that iron was produced in petitive curves along their length. There are in fact Thailand from 500 BC or earlier [26] two classes. One is that containing long blades that were used as sabers, with a slashing motion. The The crescent-bladed axe was found a short dis- other class is that of short stabbing blades. All are tance from the Late Iron Age mound site of No double edged. It is believed that the undulating Phrik which is located near Ban Hua Na village, Phu curves might make for more efficient thrusts and Luong sub-district, Loei Province. Although the carbon content was estimated as 1. 8% and the steel recoveries of the weapon. Other theories are based as concluded to be hypereutectoid, this finding was on religion. For example, under the Hindu influ- based on the assumption that the grain boundary ence, the oriental snake gad, Naga, may be repre- material was all massive carbide. It is not clear to sented in the serpentine curves. Unlike Japanese the present authors that this is the case at all, and the swords, the kisses bear no names, dates, or places steel may in fact be hypoeutectoid. Nonetheless, the of manufacture. although there are over 30 different artifact is an example of an axe that has a relatively types that can be associated with different regions massive cutting head formed by welding a layer The blades are usually laminated; in fact, the name carbon steel onto a wrought iron core for the most popular ones is pamur, a Malay word In the microstructure of a second artifact, an iron for combination or mixture. Smith [16 included socketted chisel, a"laminated semi-circular pattem is excellent examples of surface patterns in his book readily visible. "Hogan and Rutnin[25] proposed that on historical metallurgy; and the detailed manufac the manufacturing process was"a simple procedure." ture of a relatively modern kris also has been described by the famous metallurgist Walter Rosen- The starting material was piled wrought iron, made hain [27] by hammering sponge from the smelting furnace A typical Indonesian kris is shown in Fig. 7(a), to thin sheets, then folding and re-folding while and an interesting example of a specialized execu- ot and hammering them together to form a sha tioners kris, with a straight blade is shown in Fig uired for sale to blacksmiths. When re-heated 7(b). In this case, as with others, one of the layers is he forge the surface of each sheet may be either meteoric iron containing Ni. According to Smith xidised or reduced. so that the carbon content kisses were made from about 1379 AD onward different in surface and centre of the sheets. when these sheets are welded together the laminated in Indonesia under Hindu influences. From the description by Rosenhain, the modern kris was made by solid-state ng of a tool steel Laminations were also evident in an iron sock- high-carbon steel' such as is commonly used for etted spearhead which tools and cutlery, "to quote Rosenhain) to welded yers of wrought iron. In addition, according to appears to have been made in a sandwich construction Rosenhain [27] carbon strip of the iron, lying parallel to the top The imperfection of the [solid-state) welds between surface.. This was sandwiched between strips of the wrought iron [layers]also play an important part soft, low-carbon iron and the sandwich forge welded in the formation of the damask pattem. Thu 2.10. Halberds of the spear can always be resharpened to give A halberd is a weapon that is both a spear and a elatively hard, sharp point, while the soft outer battle ax that was used in warfare in the 15th to 16th yers are more easily ground to remove the bulk of century. According to Meier [28], statements regard
2.8. Thailand axes and tools Although less extensively developed than the Indonesian metal krisses (next section), there are interesting artifacts originating in Thailand. In a study of such objects [25], four iron artifacts were excavated in Northeast Thailand and three were dated to the Late Iron Age (e.g., 300 ± 400 AD). The fourth artifact, dated by association with the other three, involved welding an ultrahigh carbon content steel onto a wrought iron core to form a high quality axe blade. In concluding that the artifacts date to the Late Iron Age, the authors note that iron was produced in Thailand from 500 BC or earlier [26]. The crescent-bladed axe was found a short distance from the Late Iron Age mound site of Non Phrik which is located near Ban Hua Na village, Phu Luong sub-district, Loei Province. Although the carbon content was estimated as 1.8% and the steel was concluded to be hypereutectoid, this finding was based on the assumption that the grain boundary material was all massive carbide. It is not clear to the present authors that this is the case at all, and the steel may in fact be hypoeutectoid. Nonetheless, the artifact is an example of an axe that has a relatively massive cutting head formed by welding a layer of carbon steel onto a wrought iron core. In the microstructure of a second artifact, an iron socketted chisel, a ``laminated semi-circular pattern is readily visible.'' Hogan and Rutnin [25] proposed that the manufacturing process was ``a simple procedure.'' The starting material was piled wrought iron, made by hammering sponge from the smelting furnace into thin sheets, then folding and re-folding while hot and hammering them together to form a shape required for sale to blacksmiths. When re-heated in the forge the surface of each sheet may be either oxidised or reduced, so that the carbon content is different in surface and centre of the sheets. When these sheets are welded together the laminated appearance results. Laminations were also evident in an iron socketted spearhead which: ...appears to have been made in a sandwich construction, commencing with a relatively highcarbon strip of the iron, lying parallel to the top surface.... This was sandwiched between strips of soft, low-carbon iron and the sandwich forge welded and shaped... Thus, the: ...use of a higher carbon core ensures that the point of the spear can always be resharpened to give a relatively hard, sharp point, while the soft outer layers are more easily ground to remove the bulk of the metal required for sharpening. The higher carbon central strip would have been prepared by the smith by cementation, ie [sic] by burying a thin strip of low-carbon iron about 1 mm thick in a charcoal fire with limited air access to give a reducing atmosphere, rich in carbon monoxide. 2.9. Indonesian kris The Indonesians of Java and other Malayan Islands made a number of knives known as krisses. Indonesian krisses usually are forged to have repetitive curves along their length. There are in fact two classes. One is that containing long blades that were used as sabers, with a slashing motion. The other class is that of short stabbing blades. All are double edged. It is believed that the undulating curves might make for more efficient thrusts and recoveries of the weapon. Other theories are based on religion. For example, under the Hindu influence, the oriental snake gad, Naga, may be represented in the serpentine curves. Unlike Japanese swords, the krisses bear no names, dates, or places of manufacture, although there are over 30 different types that can be associated with different regions. The blades are usually laminated; in fact, the name for the most popular ones is pamur, a Malay word for combination or mixture. Smith [16] included excellent examples of surface patterns in his book on historical metallurgy; and the detailed manufacture of a relatively modern kris also has been described by the famous metallurgist Walter Rosenhain [27]. A typical Indonesian kris is shown in Fig. 7(a), and an interesting example of a specialized executioner's kris, with a straight blade, is shown in Fig. 7(b). In this case, as with others, one of the layers is meteoric iron containing Ni. According to Smith, krisses were made from about 1379 AD onward in Indonesia under Hindu influences. From the description by Rosenhain, the modern kris was made by solid-state welding of a tool steel (``a `high-carbon steel' such as is commonly used for tools and cutlery,'' to quote Rosenhain) to welded layers of wrought iron. In addition, according to Rosenhain [27]: The imperfection of the [solid-state] welds between the wrought iron [layers] also play an important part in the formation of the damask pattern. 2.10. Halberds A halberd is a weapon that is both a spear and a battle ax that was used in warfare in the 15th to 16th century. According to Meier [28], statements regardJ. Wadsworth, D.R. Lesuer / Materials Characterization 45 (2000) 289±313 297