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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 1980’s 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

  1. Agrawal, D. P. and Ghosh, A. (eds.). 1971, The Copper- bronze Age in India. Munshiram Manoharlal, New Delhi.
  2. Agrawal. O. P., Narain, H., Prakash, J. and Bhatia, S. K. 1992, Development of Iron Metallurgy in Ancient India, Archeometallurgia Richerche e Prospettive, Bologna.
  3. Anantharaman, T. R. 1997, The Rustless Wonder, Vigyan Prasar, New Delhi.
  4. Prakash, B. (ed.) 1997 (in press), Archaeometallurgy, Proceedings of the World Archaeology Congress-3 held at New Delhi, Dec. 1994, Routledge, London.
  5. Bhardwaj, H. C. 1979, Aspects of Ancient Indian Technology, Munshiram Manoharlal, New Delhi.
  6. Biswas, A. K. and Biswas, S. 1996, Minerals and Metals in Ancient India, 2 vol. D.K. Printworld, New Delhi.
  7. Chakrabarti, D. K. 1992, The Early Use of Iron in India, Oxford University Press, New Delhi.
  8. Craddock, P. T. 1995, Early Metal Mining and Production, University Press, Edinburgh.
  9. Ganorkar, M. C. and Rama Rao, N. (eds), 1991, Role of Chemistry in Archaeology, Birla Archaeological Institute, Hyderabad.
  10. Hegde, K. T. M. 1991, An Introduction to Ancient Indian Metallurgy, Geological Society of India, Bangalore.
  11. Kuppuram, G. 1989, Ancient Mining, Metallurgy and Metal Industries in India, 2 vols. Sundeep Prakashan, New Delhi.
  12. Radhakrishna, B. P and Curtis, L. C. 1991, Gold, The Indian Scene. Geological Society of India, Bangalore,
  13. Smith, C. S. 1981, A Search for Structure, MIT Press, Boston.
  14. 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.
  15. Sundaram, C. V., N Rajagopalan and Baldev Raj (eds.) 1997, (In Press) Where Gods Come Alive, Vigyan Prasar, New Delhi.
  16. 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.
  17. Srinivasan, S and Glover, S., Wrought and quenched, and cast high tin bronzes from Kerala, Journal of Historical Metallurgy, 29(2), London
  18. 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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