STAINLESS STEEL in ancient India
Sushruta Samhita is one of the most elaborate books on medicine ever. Though some chapters have been lost, what remains is a huge encyclopedia of all aspects of medicine.
Speaking exhaustively about surgery Sushruta makes numerous observations. Two of them are, about the material for surgical instruments, and the need for practice.
Shuddha-shaikya-âyasa means stainless steel or Wootz Steel or Damask Steel or Damascus steel.
Ancient Tamilnadu was well-known for the manufacture of stainless steel of supreme quality. Stainless Steel was the best for surgery, and it was introduced to the world from India, like surgery itself.
Wootz steel or Damascus steel is one of the wonders of the ancient world. With its characteristic meandering pattern, the steel alloy is known as Wootz steel (derived from the Tamil word ‘Urukh’) still a towering example of metallurgy to this day.
Incidentally, though the swords made from the steel, Damascus swords, are famous around the world, few seem to realize that the swords were made from ingots forged in India.
Way back in the 6th century BC, this finest of alloys being made was in the Chera Kingdom of Tamil Nadu, from where it spread far and wide.
Developed by the Tamils themselves, the alloy is made by hammering porous iron while it is hot.
Then, the metal is sealed in a clay container with wood chips. When heated, the wood turns to carbon, which binds with the iron to make steel. At least that is how we speculate that they did it. The real technique has been lost to history. And it may be far more complicated than that.
But now, we may be one step closer to proving this theory, thanks to two inter-connected papers published by Prof Sharada Srinivasan from the National Institute of Advanced Studies (NIAS), Bengaluru.
Prof Srinivasan has been studying wootz steel for quite a while. She has published several research papers on the subject, highlighting the importance of metallurgy.
Previously, alloys like these were thought to be made either by fusing cast iron and wrought iron or by adding carbon to wrought iron through various means. But it has been difficult to find clinching evidence to prove with certainty which technique made the ultrahigh-carbon steel of the Tamils all those centuries ago.
Prof Srinivasan may, at last, have some answers for this. In her new paper, she states that her research has indicated that this type of high carbonaceous steel could only be achieved by packing the iron blooms with carbonaceous materials like wood, and firing the furnace at high temperatures, not less than 1,400°C for a long time.
This method, dubbed by the paper as the ‘Tamil Nadu Process’, could only be achieved by skilled personnel with a deep understanding of the metallurgy of those times.
Prof Srinivasan discovered that Adichanallur’s beta bronze had a very high percentage of tin, 23%. This composition increases the malleability of the alloy, which can then be worked on to a considerable degree at high temperatures, followed by rapid cooling, improving the tensile strength and tonality of the bronze.
She figured out that the only way they could create alloys with such high proportions of tin was by heavy hot-forging. That is, the temperature of the crucible in which the alloy was made had to be very high and consistent.
Investigations on the crucible fragments of Mel Siruvalur have shown that these crucibles are made of ‘hypereutectoid’ or ultra-high carbon steel.
Her further research into these crucibles led her to her the current paper.
Speaking to Research Matters, Prof Srinivasan commented on its importance, “There has to be more awareness of the need to also preserve such aspects of scientific and technological heritage for posterity. There is also a need to foster more interest in the disciplinary study of scientific archaeology.”
Link to original articles are provided below.
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