Le
damas ? / Qu'est ce que le damas ? / Le wootz / Heritage of India
METALLURGICAL
HERITAGE OF INDIA
Mise
à jour G.E. le 18 novembre 2000
Texte
de :
S.
Srinivasan and S. Ranganathan
Department of Metallurgy
Indian Institute of Science
Bangalore
Seuls
les paragraphes généraux et ceux concernant l'acier
damas sont ici présents, vous trouverez un lien pour le
texte complet de la page "METALLURGICAL HERITAGE OF INDIA"
du site de l'Indian Institute of Science sur ma page des liens
en anglais. (Note de G.E.)
Des
mêmes auteurs, un autre texte très intéressant
:
WOOTZ
STEEL: AN ADVANCED MATERIAL OF THE ANCIENT WORLD
The
history of civilization is in many ways linked to the story of
the use of metals in antiquity. Although modern metallurgy has
seen an exponential growth since the Industrial Revolution it
is interesting that many modern concepts in metallurgy have their
seeds in ancient practices that pre-date the Industrial Revolution.
Metals were extracted and utilized in the past in stages progressing
usually from the use of native metal, to those metals which could
be smelted easily from ores, to those which were more difficult
to smelt. The commonly used metals in antiquity include gold,
silver, copper, iron, tin, lead, zinc and mercury. This brief
review takes a synoptic look at some aspects of the early use
of metal in a global perspective. It throws light on some of the
achievements of ancient Indian metallurgists. Its heritage in
metallurgy, medicine, mathematics and astronomy is a matter of
pride for India.
...
Iron
Iron
occurs in the native metal state as meteoric iron which was exploited
by the North American Indians to make weapons. Since iron has
a high melting point of around 1550oC it was commonly
produced in the Old World by reducing the ore to metal in the
solid state to produce bloomery iron which was then wrought to
give low carbon wrought iron (0.1-0.2 % C). The Hittite kingdom
of the mid second millennium BC was one of the major early iron
producing centers and was thought to have a monopoly of iron production,
and iron production became widespread in Greece and the Mediterranean
by the beginning of the 1st millennium BC. Iron seems to have
been used in India from about the late second millennium BC and
iron smelting and the use of iron was especially well established
in the south Indian megalithic cultures of this period.
The
forging of wrought iron seems to have reached its zenith in India
in the first millennium AD. The earliest large forging is the
famous iron pillar at New Delhi dated by inscription to the Gupta
period of the 3rd c. AD at a height of over 7 m and weight of
about 6 tons. The pillar is believed to have been made by forging
together a series of disc-shaped iron blooms. Apart from the dimensions
another remarkable aspect of the iron pillar is the absence of
corrosion which has been linked to the composition, the high purity
of the wrought iron and the phosphorus content and the distribution
of slag.
In
fact the use of high-carbon iron alloys was developed in parts
of Asia before they came into vogue in Europe. We may mention
high-carbon steel from India and cast iron from China, both of
which required higher furnace temperatures and more reducing conditions
than the bloomery iron process. Cast iron was produced in China
prior to other parts of the world in small blast furnaces which
were precursors to the modern blast furnaces. Cast iron with a
high carbon content of between 2-4% C is a brittle and fairly
unworkable alloy with poor strength, but it has the lowest melting
point in the iron-carbon system being a eutectic at around 1100oC.
By the early Christian era in China cast iron was used on a very
large scale for producing tools, weapons, vessels and utensils.
In
Europe the use of cast iron was not appreciated until after about
the 14th c. AD when it was used for making cannons. By the end
of the 18th century cast iron began to be used extensively in
England in building and construction. The famous Mysore Palace
in Mysore near Bangalore built by the Wodeyars at the turn of
the century was the first royal palace in India to make use of
cast iron in architectural construction.
Steel
India
has been reputed for its iron and steel since Greek and Roman
times with the earliest reported finds of high-carbon steels in
the world coming from the early Christian era, while Greek accounts
report the manufacture of steel in India by the crucible process.
Wootz is the anglicized version of ukku in the languages
of the states of Karnataka, and Andhra Pradesh, a term denoting
steel. Literary accounts suggest that steel from the southern
part of the Indian subcontinent was exported to Europe, China,
the Arab world and the Middle East. In the 12th century the Arab
Idrisi says The Hindus excel in the manufacture of iron.
It is impossible to find anything to surpass the edge from Indian
steel.
Studies
on Wootz indicate that it was an ultra-high carbon steel with
between 1-2% carbon and was believed to have been used to fashion
Damascus blades with a watered steel pattern (Srinivasan and Griffiths
1997). Experimental reconstructions by Wadsworth and Sherby in
the 1980s have demonstrated that ultra-high carbon steels
with about 1.5% C can be used to simulate Damascus
blades and that these exhibit fascinating superplastic properties.
Superplasticity is a remarkable phenomenon which allows a material
to change its external shape to a very great extent without changing
within.
A
description from the Crusades of the Damascus blades is as follows:
One blow of a Damascus sword would cleave a European helmet
without turning the edge or cut through a silk handkerchief drawn
across it. One sixth century writer describes blades
as having a water pattern whose wavy streaks are glistening-it
is like a pond on whose surface the wind is gliding.
Wootz
steel also played an important role in the development of metallurgy.
Michael Faraday, the greatest experimenter of all times, tried
to duplicate the steel by alloying iron with a variety
of metallic additions including noble metals but failed. As he
was the son of a blacksmith the extraordinary properties of Wootz
steel must have fascinated him. His failure had an unexpected
and fortunate outcome as it marked the beginning of alloy steel
making. Wootz has been a prime motivating force in the development
of metallurgical science and the study of micro-structures. Although
iron and steel had been used for thousands of years the role of
carbon in steel as the dominant element was found only in 1774
by Tobern Bergman and was due to the efforts of Europeans to unravel
the mysteries of Wootz. Similarly the textured Damascus steel
was one of the earliest materials to be examined by the microscope.
British, French and Russian metallography developed largely due
to the quest to document this structure. Wootz was an advanced
material of the ancient world used in three continents for
well over a millennium. Neither its geographic sway nor its historic
dominance is likely to be equalled by advanced materials of our
era.
...
The
above review indicates that there is growing evidence to suggest
that ancient Indian metallurgists have also made major contributions
which deserve their place in the metallurgical history of the
world along with other great civilizations of the world. As clearly
seen in the case of zinc and high-carbon steel, ancient India
contributed significantly to their modern metallurgical advances
and in the development of metallurgical study leading to the Industrial
Revolution in Europe and hence deserve a special niche in the
annals of western science. In this Golden Jubilee year of the
department it is worth recalling the achievements of the past
as a source of inspiration and confidence for future generation
of metallurgists in India and elsewhere. Prof. Cyril Stanley Smith
has remarked that usually man assays metals. Metal can just as
well be used to assay the progress of mankind. In this assay the
ancient civilisation of India acquits itself with glory.
Acknowledgements
The
authors would like to thank the Indian National Academy of Engineering
(INAE) and one of the authors (SS) would like to thank the Homi
Bhabha Fellowships Council for their support and British Council,
New Delhi for support to the Phd. research at University College
London.
Suggestions
for further reading
- Agrawal,
D. P. and Ghosh, A. (eds.). 1971, The Copper- bronze Age
in India. Munshiram Manoharlal, New Delhi.
- Agrawal.
O. P., Narain, H., Prakash, J. and Bhatia, S. K. 1992, Development
of Iron Metallurgy in Ancient India, Archeometallurgia Richerche
e Prospettive, Bologna.
- Anantharaman,
T. R. 1997, The Rustless Wonder, Vigyan Prasar, New Delhi.
- Prakash,
B. (ed.) 1997 (in press), Archaeometallurgy, Proceedings
of the World Archaeology Congress-3 held at New Delhi, Dec.
1994, Routledge, London.
- Bhardwaj,
H. C. 1979, Aspects of Ancient Indian Technology, Munshiram
Manoharlal, New Delhi.
- Biswas,
A. K. and Biswas, S. 1996, Minerals and Metals in Ancient
India, 2 vol. D.K. Printworld, New Delhi.
- Chakrabarti,
D. K. 1992, The Early Use of Iron in India, Oxford University
Press, New Delhi.
- Craddock,
P. T. 1995, Early Metal Mining and Production, University
Press, Edinburgh.
- Ganorkar,
M. C. and Rama Rao, N. (eds), 1991, Role of Chemistry in
Archaeology, Birla Archaeological Institute, Hyderabad.
- Hegde,
K. T. M. 1991, An Introduction to Ancient Indian Metallurgy,
Geological Society of India, Bangalore.
- Kuppuram,
G. 1989, Ancient Mining, Metallurgy and Metal Industries
in India, 2 vols. Sundeep Prakashan, New Delhi.
- Radhakrishna,
B. P and Curtis, L. C. 1991, Gold, The Indian Scene.
Geological Society of India, Bangalore,
- Smith,
C. S. 1981, A Search for Structure, MIT Press, Boston.
- Srinivasan,
1997(In press), Archaeometallurgy of Bronze Images and High-tin
Bronzes from South India, (D.Phil. thesis research, University
College London), Indicopleustoi & IGNCA, Brussels.
- Sundaram,
C. V., N Rajagopalan and Baldev Raj (eds.) 1997, (In Press)
Where Gods Come Alive, Vigyan Prasar, New Delhi.
- Srinivasan,
S., High tin bronze working in Kerala, in Tripathi, V. (ed.)Archaeometallurgy
in India, Proceedings of the First National Seminar in Indian
Archaeometallurgy, 1991, Sharda Publishing Ltd., New Delhi.
- Srinivasan,
S and Glover, S., Wrought and quenched, and cast high tin bronzes
from Kerala, Journal of Historical Metallurgy, 29(2), London
- Srinivasan,
S. and Griffiths, D., Crucible steel from south India, preliminary
investigations on some newly identified sites, in Materials
Issues in Art and Archaeology, Materials Research Society Symposium
Proceedings, Vol. 462, 1997, Materials Research Society, Pittsburgh,
USA
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