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Dr. John Verhoeven
Emeritus Professor
Iowa State University 10/2/03
In reading over your pages on Damascus I noticed that you have placed the Japanese sword as the start of the pattern welded Damascus blades. I think this is incorrect. From my readings I am fairly certain that the pattern welding process predates both the Japanese blades and the genuine Damascus blades that produced the name Damascus. I recently summarized my findings from reading the literature in a paper published in a German journal called Steel Research, page 356, August 2002. Here are the sections on history:
Historical Background of Damascus blades
by
Dr. John Verhoeven, metallurgist
It is generally agreed that our ancestors first learned to reduce iron ores to pure iron around 1200 BC [1-3]. The iron formed without melting in a charcoal fired furnace and sintered together with abundant slag inclusions into a mass called a bloom. It had to be hot forged to remove most of the slag inclusions. This bloomery iron was very low in carbon, around 0.06%, and was full of elongated slag inclusions. It was the main source of iron (except in China) up to the late 14th century when European smiths learned to make their furnaces higher, run them hotter and produce a cast iron which was then processed to a wrought iron that was amazingly similar to bloomery iron [4]. Virtually all early steel was made by carburizing the bloomery iron in charcoal fires with the CO/CO2 ratio controlled properly to give high carbon potentials in iron at temperatures above around 850 oC where the kinetics of carbon diffusion was appreciable. It was not until the late 18th century that the element C was discovered and it was even later that it was learned that the key factor in making hardened steel was adding the element carbon to iron and quenching from high temperatures. Nevertheless early smiths successfully produced martensitic steel as early as 1200 BC
[3]. Proper control of temperature and flow rate of the air into the hot forge fire to give the needed CO/CO2 ratio to ensure adequate carburization was an art learned only by the more clever bladesmiths.
Swords made from bloomery iron where relatively soft and so steel swords were prized. Most of the steel swords made prior to around 200 AD utilized a process called "piling" [5, 6]. Carburized rods or plates were stacked together and then hot forged to form the blade. Starting around 200 AD the method of pattern welding began to appear [5, 6]. This method, first named by Maryon [7, 8], is similar to piling but a bit more complex. It often involves the addition of folding during the forging process and the use of twisted aggregates of rods in the starting material. Polishing and etching of the surface of the blade generally produces a pattern due to the effect of differences of chemical compositions in the various starting layers on etching response. Modern bladesmiths produce beautiful patterns on blade surfaces using pattern welding, and perhaps the most famous example occurs in pattern welded shotguns. Such steels are now called pattern welded Damascus steel and ref. [9] presents beautiful examples along with the details of how the various patterns are formed by controlling the arrangement and twisting of the various starting elements that are hot forged together.
When the Christian warriors of Europe encountered Moslem armies during Crusade times they discovered that the Moslems had steel swords superior to their own steel swords. Historical accounts [10, 11] claim that the swords were encountered by Europeans in Damascus and hence the name, but they were also known in Russia in the same time period under the names "poulad" or "bulat". It is agreed that the swords were forged directly from small ingots of steel formed in crucibles and given the name wootz by English people in 1795 [4]. This steel is widely regarded as a product of India.
Bronson [12] has shown that it first appeared around the second century AD, but that it was also produced in the Middle East. More recently, Feuerbach et. al, [13] has shown that crucible steel was also produced in Central Asia over 1000 years ago. The crucible steel of Damascus swords is a surprisingly clean hypereutectoid steel with %C in the range of 1.1 to 1.8%, see top 2 rows of Table 1. An outstanding collection of high quality Damascus swords was obtained by L.S. Figiel and beautiful pictures of these swords are found in his book [14]. Similar blades may be found in the arms and armor section of most large museums. Figure 1 presents an example sword, No. Ps4 [14], a sword made in 1691-2 by Asaad Allah, reportedly one of the most famous swordsmiths of the 17th century. The inset shows the details of a typical Damascus blade pattern along with an inscription on the blade identifying the swordsmith. The patterns on Damascus swords and knives appear only on the better quality blades and are commonly referred to as a damascence pattern. It was because of the fact that well made pattern welded swords have surface patterns of a somewhat similar nature that these blades are also called Damascus blades. Because the name Damascus was first used to refer to blades made from wootz steel these blades will be called genuine Damascus blades here and the other blades called pattern welded Damascus blades.
There is a general myth in some of the popular literature that genuine Damascus steel blades possess outstanding mechanical properties, often thought superior to modern steels. This idea was shown to be incorrect as long ago as 1924. A famous Swiss collector, Henri Moser, donated 4 genuine Damascus steel swords, one with a non typical carbon content and microstructure, to B. Zschokke, who performed extensive careful experiments including metallographic and chemical analysis in addition to mechanical testing [15]. A series of bending tests compared samples from the swords to a pattern welded blade and a cast blade from the famous German knife center in Solingen. The 3 good Damascus blades showed significantly inferior bending deflection prior to breakage than the 2 Solingen blades in spite of the fact that the Brinell hardness of the 3 ranged from only 193 to 248, compared to 347 and 463 for the pattern welded and cast Solingen blade, respectively. This is not too surprising in view of the now well known fact that toughness of high carbon steels is inherently low; the Solingen blades had carbon levels of 0.5 to 0.6% compared to 1.3 to 1.9% for the 3 Damascus blades. The reputation of Damascus steel blades being superior to European blades was probably established prior to the 17th century when European blades were still being made by forge welding of carburized iron. It is hard to avoid embrittlement of such blades due to imperfect welding during the forging process as well as difficulty with the carburizing process.
There is a parallel here with the famous crucible steel of Huntsman in 1740 England, essentially a rediscovery of the wootz steel. Huntsmen's motivation for the development of crucible steel was to overcome the lack of toughness of blister steel, which was made by the carburizing process descended from the old piling process.
References
1 R. Pleiner, Early iron metallugy in europe, p 375-416, The coming of the age of iron, Ed, T.A. Werthime and J.D. Muhly (1980).
2 J Waldbaun, The first archaeological apperance of iron and the transition to the iron age, 69-98, The coming of the age of iron, Ed. T.A.
Werthime and J.D. Muhly (1980).
3 R. Maddin, A History of Martensite, p. 11-19, Martensite, Ed. G.B.
Olsen and W.S. Owen, ASM International (1992).
4 W. Rostoker and B. Bronson, pre-industrial iron, its technology and ethnology, p. 127, Archeomaterials monogrph No. 1, Philidelphia, PA (1990).
5 R.F. Tylecote, The prehistory of metallurgy in the British Isles, Chaps 6-8, The institute of metals, London (1986).
6 R.F. Tylecote and B.J.J. Gilmour, The metallography of early ferrous edge tools and edged weapons, BAR British Series 155, Oxford England (1986).
7 H. Maryon, A sword of the Nydam typ from Ely Fields Farn, near Ely, Cambridge Antiquarian Society Journal, XLI 41, 73-76(1948).
8 H. Maryon, Pattern-welding and damascening of sword blades-Part I, pattern welding, Studies in Conservation, vol. 5, 25-36 (1960).
9 M. Sachse, damaszener stahl: mythos, geschichte, technik, anwendung, Wirtschaftsverlag NW, verl, fur neue wiss. (1989). English translation: Verlag Stahleisen, Dusseldorf (1994).
10 N. Belaiew, damascene steel, J Iron Steel Inst. London, vol. 97, 417-439 (1918).
11 C.S. Smith, A history of metallography, Chaps. 3 and 4, Second edition, MIT Press, Cambridge, MA (1988).
12 B. Bronson, the making and selling of wootz, a crucible steel of
india, Archeomaterials, vol. 1, 13-51 (1986).
13 A.M. Feuerbach, J.F. Merkel and D.R. Griffiths, An examination of crucible steel in the manufacture of Damascus steel, including evidence from Merv, Turkmeenistan, Metallurgica Antiqua, Der anschnitt, beiheft 8, 37-44 (1998).
14 L.S. Figel, On Damascus Steel, Atlantis Arts Press, The Print Center,225 Varick St. N.Y., N.Y., 10014 (1991).
15 B. Zschokke, Du Damasse it des Lames de Damas, Rev. Met. vol. 21,635-69(1924).