Wootz steel
Encyclopedia
Wootz steel is a steel
characterized by a pattern of bands or sheets of micro carbide
s within a tempered martensite
or pearlite
matrix. It was developed in India
around 300
BCE. The word wootz may have been a mistranscription of wook, an anglicised version of urukke the word for steel in Tamil
and Malayalam or ukku, the word for steel in Kannada, Telugu
and many other southern Indian languages.
and the Arab
world, and became particularly famous in the Middle East
, where it was known as Damascus steel
and was later traced to workshops in western India.
In ancient times, thirty pounds of steel was a precious gift, deemed by King Porus worthy of presentation to Alexander the Great. Another sign that Ancient India was celebrated for its steel is seen in a Persian phrase - to give an "Indian answer," meaning "a cut with an Indian sword."
alloy
s were not known in Europe previously and thus the research into wootz steel played an important role in the development of modern English, French and Russian metallurgy
.
in the 1750s gave a fresh impetus for western research. By 1790, samples of wootz steel were received by Sir Joseph Banks
, President of the British Royal society
. These samples were subjected to scientific examination and analysis by several experts.
Specimens of daggers, and other warlike weapons were sent by the Rajahs of India to the International Exhibition of 1851
and 1862
. Though the arms of the swords were beautifully decorated and jeweled, they were most highly prized for the quality of their steel. The swords of the Sikhs were said to bear bending and crumpling, and yet be fine and sharp.
.
While other methods may be used today, it is known that wootz was classically made in crucible
s, e.g., crucible steel
by combining a mixture of wrought iron
or iron ore and charcoal
with glass
, which is then sealed and heated in a furnace
. The result is a mixture of impurities mixed with glass as slags, and "buttons" of steel. The buttons (with a typical carbon content of 1.5%) were separated from the slag
and forged
into ingot
s. The ingots could be further forged out into blades/tools or welded
to other ingots to increase the mass of the steel for larger items.
The ore was beaten with a stone hammer into a bar, then cut into small pieces and placed in crucibles, with green berries and dry wood. Much importance was given to the kind of wood used, as it influenced the kind of steel produced. Steel manufactured in Kutch
particularly enjoyed a widespread reputation, similar to those manufactured at Glasgow
and Sheffield
.
The techniques for its making died out around 1700 after the principal sources of special ores needed for its production were depleted. Those sources contained trace amounts of tungsten
and/or vanadium
which other sources did not. Oral tradition
in India maintains that a small piece of either white or black hematite
(or old wootz) had to be included in each melt, and that a minimum of these elements must be present in the steel for the proper segregation of the micro carbides to take place.
Wootz was possibly rediscovered in the mid 19th century by the Russian metallurgist Pavel Petrovich Anosov (see Bulat steel
), who refused to reveal the secret of its manufacture other than to write five one-sentence descriptions of different ways in which it could be made.
Master bladesmith Alfred Pendray re-discovered what may be the classic techniques in the early 1980s, as later verified by Dr. John Verhoeven.
Another method of wootz production, using modern technology, was developed around 1980 by Dr. Oleg Sherby and Dr. Jeff Wadsworth at Stanford University
and Lawrence Livermore National Laboratory
. Even though this steel had the characteristic bands of microcarbides, whether or not this could be considered wootz was disputed by Verhoeven since it was not made in a classical manner.
Recently, researcher Peter Paufler from Dresden University of Technology in Germany has discovered evidence of carbon nanotubes in wootz steel, although this is disputed.
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
characterized by a pattern of bands or sheets of micro carbide
Carbide
In chemistry, a carbide is a compound composed of carbon and a less electronegative element. Carbides can be generally classified by chemical bonding type as follows: salt-like, covalent compounds, interstitial compounds, and "intermediate" transition metal carbides...
s within a tempered martensite
Martensite
Martensite, named after the German metallurgist Adolf Martens , most commonly refers to a very hard form of steel crystalline structure, but it can also refer to any crystal structure that is formed by displacive transformation. It includes a class of hard minerals occurring as lath- or...
or pearlite
Pearlite
Pearlite is often said to be a two-phased, lamellar structure composed of alternating layers of alpha-ferrite and cementite that occurs in some steels and cast irons...
matrix. It was developed in India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
around 300
300
Year 300 was a leap year starting on Monday of the Julian calendar. At the time, it was known as the Year of the Consulship of Constantius and Valerius...
BCE. The word wootz may have been a mistranscription of wook, an anglicised version of urukke the word for steel in Tamil
Tamil language
Tamil is a Dravidian language spoken predominantly by Tamil people of the Indian subcontinent. It has official status in the Indian state of Tamil Nadu and in the Indian union territory of Pondicherry. Tamil is also an official language of Sri Lanka and Singapore...
and Malayalam or ukku, the word for steel in Kannada, Telugu
Telugu language
Telugu is a Central Dravidian language primarily spoken in the state of Andhra Pradesh, India, where it is an official language. It is also spoken in the neighbouring states of Chattisgarh, Karnataka, Maharashtra, Orissa and Tamil Nadu...
and many other southern Indian languages.
History
According to traditional history wootz steel originated in India before the beginning of the common era. There is archaeological evidence of the manufacturing process in South India from that time. Wootz steel was widely exported and traded throughout ancient EuropeEurope
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and the Arab
Arab
Arab people, also known as Arabs , are a panethnicity primarily living in the Arab world, which is located in Western Asia and North Africa. They are identified as such on one or more of genealogical, linguistic, or cultural grounds, with tribal affiliations, and intra-tribal relationships playing...
world, and became particularly famous in the Middle East
Middle East
The Middle East is a region that encompasses Western Asia and Northern Africa. It is often used as a synonym for Near East, in opposition to Far East...
, where it was known as Damascus steel
Damascus steel
Damascus steel was a term used by several Western cultures from the Medieval period onward to describe a type of steel used in swordmaking from about 300 BCE to 1700 CE. These swords are characterized by distinctive patterns of banding and mottling reminiscent of flowing water...
and was later traced to workshops in western India.
In ancient times, thirty pounds of steel was a precious gift, deemed by King Porus worthy of presentation to Alexander the Great. Another sign that Ancient India was celebrated for its steel is seen in a Persian phrase - to give an "Indian answer," meaning "a cut with an Indian sword."
Wootz steel and development of modern metallurgy
Legends of wootz steel and Damascus swords aroused the curiosity of the European scientific community from the 17th to the 19th Century. The use of high carbonCarbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...
s were not known in Europe previously and thus the research into wootz steel played an important role in the development of modern English, French and Russian metallurgy
Metallurgy
Metallurgy is a domain of materials science that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their mixtures, which are called alloys. It is also the technology of metals: the way in which science is applied to their practical use...
.
Western research
The presence of British in IndiaCompany rule in India
Company rule in India refers to the rule or dominion of the British East India Company on the Indian subcontinent...
in the 1750s gave a fresh impetus for western research. By 1790, samples of wootz steel were received by Sir Joseph Banks
Joseph Banks
Sir Joseph Banks, 1st Baronet, GCB, PRS was an English naturalist, botanist and patron of the natural sciences. He took part in Captain James Cook's first great voyage . Banks is credited with the introduction to the Western world of eucalyptus, acacia, mimosa and the genus named after him,...
, President of the British Royal society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
. These samples were subjected to scientific examination and analysis by several experts.
Specimens of daggers, and other warlike weapons were sent by the Rajahs of India to the International Exhibition of 1851
The Great Exhibition
The Great Exhibition of the Works of Industry of all Nations or The Great Exhibition, sometimes referred to as the Crystal Palace Exhibition in reference to the temporary structure in which it was held, was an international exhibition that took place in Hyde Park, London, from 1 May to 15 October...
and 1862
1862 International Exhibition
The International of 1862, or Great London Exposition, was a world's fair. It was held from 1 May to 1 November 1862, beside the gardens of the Royal Horticultural Society, South Kensington, London, England, on a site that now houses museums including the Natural History Museum and the Science...
. Though the arms of the swords were beautifully decorated and jeweled, they were most highly prized for the quality of their steel. The swords of the Sikhs were said to bear bending and crumpling, and yet be fine and sharp.
Manufacturing techniques
A critical characteristic of wootz steel is the abundance of ultrahard metallic carbides in the steel matrix precipitating out in bands, making wootz steel display a characteristic banding on its surface. Wootz swords, especially Damascus blades, were renowned for their sharpness and toughnessToughness
In materials science and metallurgy, toughness is the ability of a material to absorb energy and plastically deform without fracturing; Material toughness is defined as the amount of energy per volume that a material can absorb before rupturing...
.
While other methods may be used today, it is known that wootz was classically made in crucible
Crucible
A crucible is a container used for metal, glass, and pigment production as well as a number of modern laboratory processes, which can withstand temperatures high enough to melt or otherwise alter its contents...
s, e.g., crucible steel
Crucible steel
Crucible steel describes a number of different techniques for making steel in a crucible. Its manufacture is essentially a refining process which is dependent on preexisting furnace products...
by combining a mixture of wrought iron
Wrought iron
thumb|The [[Eiffel tower]] is constructed from [[puddle iron]], a form of wrought ironWrought iron is an iron alloy with a very low carbon...
or iron ore and charcoal
Charcoal
Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...
with glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
, which is then sealed and heated in a furnace
Furnace
A furnace is a device used for heating. The name derives from Latin fornax, oven.In American English and Canadian English, the term furnace on its own is generally used to describe household heating systems based on a central furnace , and sometimes as a synonym for kiln, a device used in the...
. The result is a mixture of impurities mixed with glass as slags, and "buttons" of steel. The buttons (with a typical carbon content of 1.5%) were separated from the slag
Slag
Slag is a partially vitreous by-product of smelting ore to separate the metal fraction from the unwanted fraction. It can usually be considered to be a mixture of metal oxides and silicon dioxide. However, slags can contain metal sulfides and metal atoms in the elemental form...
and forged
Forging
Forging is a manufacturing process involving the shaping of metal using localized compressive forces. Forging is often classified according to the temperature at which it is performed: '"cold," "warm," or "hot" forging. Forged parts can range in weight from less than a kilogram to 580 metric tons...
into ingot
Ingot
An ingot is a material, usually metal, that is cast into a shape suitable for further processing. Non-metallic and semiconductor materials prepared in bulk form may also be referred to as ingots, particularly when cast by mold based methods.-Uses:...
s. The ingots could be further forged out into blades/tools or welded
Welding
Welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, with pressure sometimes...
to other ingots to increase the mass of the steel for larger items.
The ore was beaten with a stone hammer into a bar, then cut into small pieces and placed in crucibles, with green berries and dry wood. Much importance was given to the kind of wood used, as it influenced the kind of steel produced. Steel manufactured in Kutch
Kutch District
Kutch district is a district of Gujarat state in western India. Covering an area of 45,652 km², it is the largest district of India....
particularly enjoyed a widespread reputation, similar to those manufactured at Glasgow
Glasgow
Glasgow is the largest city in Scotland and third most populous in the United Kingdom. The city is situated on the River Clyde in the country's west central lowlands...
and Sheffield
Sheffield
Sheffield is a city and metropolitan borough of South Yorkshire, England. Its name derives from the River Sheaf, which runs through the city. Historically a part of the West Riding of Yorkshire, and with some of its southern suburbs annexed from Derbyshire, the city has grown from its largely...
.
The techniques for its making died out around 1700 after the principal sources of special ores needed for its production were depleted. Those sources contained trace amounts of tungsten
Tungsten
Tungsten , also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74.A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as...
and/or vanadium
Vanadium
Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery gray, ductile and malleable transition metal. The formation of an oxide layer stabilizes the metal against oxidation. The element is found only in chemically combined form in nature...
which other sources did not. Oral tradition
Oral tradition
Oral tradition and oral lore is cultural material and traditions transmitted orally from one generation to another. The messages or testimony are verbally transmitted in speech or song and may take the form, for example, of folktales, sayings, ballads, songs, or chants...
in India maintains that a small piece of either white or black hematite
Hematite
Hematite, also spelled as haematite, is the mineral form of iron oxide , one of several iron oxides. Hematite crystallizes in the rhombohedral system, and it has the same crystal structure as ilmenite and corundum...
(or old wootz) had to be included in each melt, and that a minimum of these elements must be present in the steel for the proper segregation of the micro carbides to take place.
Wootz was possibly rediscovered in the mid 19th century by the Russian metallurgist Pavel Petrovich Anosov (see Bulat steel
Bulat steel
Bulat is a type of steel alloy known in Russia from medieval times and regularly mentioned in Russian legends as material of choice for cold steel. The name булат is a Russian transliteration of the Persian word پولاد , meaning steel...
), who refused to reveal the secret of its manufacture other than to write five one-sentence descriptions of different ways in which it could be made.
Master bladesmith Alfred Pendray re-discovered what may be the classic techniques in the early 1980s, as later verified by Dr. John Verhoeven.
Another method of wootz production, using modern technology, was developed around 1980 by Dr. Oleg Sherby and Dr. Jeff Wadsworth at Stanford University
Stanford University
The Leland Stanford Junior University, commonly referred to as Stanford University or Stanford, is a private research university on an campus located near Palo Alto, California. It is situated in the northwestern Santa Clara Valley on the San Francisco Peninsula, approximately northwest of San...
and Lawrence Livermore National Laboratory
Lawrence Livermore National Laboratory
The Lawrence Livermore National Laboratory , just outside Livermore, California, is a Federally Funded Research and Development Center founded by the University of California in 1952...
. Even though this steel had the characteristic bands of microcarbides, whether or not this could be considered wootz was disputed by Verhoeven since it was not made in a classical manner.
Recently, researcher Peter Paufler from Dresden University of Technology in Germany has discovered evidence of carbon nanotubes in wootz steel, although this is disputed.
Cultural references
- An elaborate fictionalized description of wootz steel manufacture is presented in Neal StephensonNeal StephensonNeal Town Stephenson is an American writer known for his works of speculative fiction.Difficult to categorize, his novels have been variously referred to as science fiction, historical fiction, cyberpunk, and postcyberpunk...
's book The ConfusionThe ConfusionThe Confusion is a novel by Neal Stephenson. It is the second volume in The Baroque Cycle and consists of two sections or books, Bonanza and The Juncto. In 2005, The Confusion won the Locus Award, together with The System of the World....
, part of Stephenson's three-volume work The Baroque CycleThe Baroque CycleThe Baroque Cycle is a series of novels by American writer Neal Stephenson. It was published in three volumes containing 8 books in 2003 and 2004. The story follows the adventures of a sizeable cast of characters living amidst some of the central events of the late 17th and early 18th centuries in...
. - The manufacturing of wootz steel is also detailed in Leo FrankowskiLeo FrankowskiLeo Frankowski was an American writer of science fiction novels. He lived in Russia for four years with his now ex-wife and adopted teenage daughter, but...
's Conrad StargardConrad StargardConrad Stargard is the protagonist and title character in a series of time travel novels written by Leo Frankowski. In them, a Polish engineer named Conrad Schwartz is sent back in time to the 13th century where he has to establish himself and cope with various crises including the eventual...
series. - Don Krieg, an early villain in Eiichiro OdaEiichiro Odais a Japanese manga artist, best known as the creator of One Piece.-Early life:As a child, Oda was inspired by Akira Toriyama's works and aspired to become a manga artist. He recalls that his interest in pirates was probably sparked by the popular TV animation series titled Vicky the Viking...
's manga series One PieceOne Pieceis a Japanese shōnen manga series written and illustrated by Eiichiro Oda. It has been serialized in Weekly Shōnen Jump since August 4, 1997; the individual chapters are being published in tankōbon volumes by Shueisha, with the first released on December 24, 1997, and the 64th volume released as...
, wears body armor made out of wootz steel. - In the A Song of Ice and FireA Song of Ice and FireA Song of Ice and Fire is a series of epic fantasy novels by American novelist and screenwriter George R. R. Martin. Martin began writing the series in 1991 and the first volume was published in 1996. Originally planned as a trilogy, the series now consists of five published volumes; a further two...
series of novels by George R. R. MartinGeorge R. R. MartinGeorge Raymond Richard Martin , sometimes referred to as GRRM, is an American author and screenwriter of fantasy, horror, and science fiction. He is best known for A Song of Ice and Fire, his bestselling series of epic fantasy novels that HBO adapted for their dramatic pay-cable series Game of...
, a material known as Valyrian steel draws close parallels to wootz steel.
Further reading
- History and Characteristics of Wootz Steel in India and Abroad. (Indian Journal of History of Science; vol. 42, no. 3; September 2007). New Delhi: Indian National Science Academy, 2007.
- Srinivasan, Sharada & Ranganathan, Srinivasan India's Legendary Wootz Steel: an advanced material of the ancient world. Bangalore: National Institute of Advanced Studies and Indian Institute of Science, 2004.