Sarbloh

[Singh559]

That's the right explanation!! ^^

[jang123]

Wootz steel is a steel characterized by a pattern of bands or sheets of micro carbides within a tempered martensite or pearlite matrix. It is stated to have developed in India around 300 BC.^[1] However, the steel was an old technology in India when King Porus presented a steel sword to the emperor Alexander in 326 BC. The steel technology obviously existed before 326 BC as steel was being exported westward at that time. Since the technology was acquired from the Tamilians from South India, the origin of steel technology in India can be conservatively estimated at 400–500 BC.

The word wootz^[2] may have been a mistranscription of wook, an anglicised version of urukke, the word for melting in Tamil and Malayalam or urukku (உருக்கு) (ഉരുക്കു), the word for steel in Kannada, Telugu and many other southern Indian

http://en.wikipedia......<br /><br />

Heres some from what i searched on web

Wootz also had Vanadium init

"In late 2006, a group of scientists headed by Peter Paufler found direct evidence of nanotubes and nanowires in a sample of a 17th century sword forged from Damascus steel. The complex process of forging and annealing is thought to have accounted for the nano-scale structures."

Damascus steel uses Wootz

Wootz steel is stronger then folded steel that is the reason why

puratan shastars can cut a steel bar for 2.5" in one cut

the striated pattern of damascene steel is made from the striated precipitation of iron and carbon particles, you need vanadium (or equivalent) to ensure proper nucleation of the particles.

heres a video on how to make wootz steel also see its part 2

Thanks for sharing!

[singhgsingh]

I think as long as the Sarbloh rusts its ok. If it doesn't rust then it has too much carbon in it. Or has been coated with something.

[Singh559]

I think as long as the Sarbloh rusts its ok. If it doesn't rust then it has too much carbon in it. Or has been coated with something.

Now that's just silly. Imagine having a weapon like that.

If our shastar were like that we wouldn't have puratan shastar with us today. Guru Sahib's shastar were mostly made of wootz steel sarbloh.

I'm thinking some shop keeper made up that original sarbloh is the one that rusts as a gimmick. I remember reading a psychology book how you can end up selling a low end product for more by claiming it's "special". The U.S. steel baron Andrew Carnegie did a similar thing by making up some stuff about his lower quality steel somehow being better than his competitors. Consumers were dumb enough to believe it so they ended up paying more for his low quality steel haha.

Btw - all steel eventually rusts. What's the mathematical equation that defines sarbloh and rust time frame?

I went to Patiala Dukhniwaran Sahib and was looking for puratan shastar. The cheeky shop keeper took me to the back where the paiye were making shastar and he showed me a pure iron (or as you would call sarbloh) weapon that was completely filled with rust. He probably dug it into the ground for months and thought he could fool people by it lol.

There's a reason why puratan shastar that Sikhs used are still around today.

[singhgsingh]

Now that's just silly. Imagine having a weapon like that.

If our shastar were like that we wouldn't have puratan shastar with us today. Guru Sahib's shastar were mostly made of wootz steel sarbloh.

I'm thinking some shop keeper made up that original sarbloh is the one that rusts as a gimmick. I remember reading a psychology book how you can end up selling a low end product for more by claiming it's "special". The U.S. steel baron Andrew Carnegie did a similar thing by making up some stuff about his lower quality steel somehow being better than his competitors. Consumers were dumb enough to believe it so they ended up paying more for his low quality steel haha.

Btw - all steel eventually rusts. What's the mathematical equation that defines sarbloh and rust time frame?

I went to Patiala Dukhniwaran Sahib and was looking for puratan shastar. The cheeky shop keeper took me to the back where the paiye were making shastar and he showed me a pure iron (or as you would call sarbloh) weapon that was completely filled with rust. He probably dug it into the ground for months and thought he could fool people by it lol.

There's a reason why puratan shastar that Sikhs used are still around today.

I was thinking more for Bhande and Kirpan for doing Bhog to Degh. I don't have any knowledge about puratan shastars.

[GtLoc]

It's an fn sword, let it do it's job. I went on here to get away from the ritualistic ish ppl do but here ppl have even more of their own and they're EDUCATED about it.

So if they had nanotube swords (carbon ones?) that were better than anything you wouldn't use them, and be cut down cuz it ain't 'sarbloh'.

Did we have labs to certify waht was and what wasn't.

Peace

edit - Also a kirpan is not a fasion accessory, why a dif. one for bhog and for fighting.

The kirpan that's right for bhog is the one which lets you defend the sangant, and the gurughur so that a bhog may take place ie. the best the world has to offer.

We are warriors not fn turban tying sadhus.

[savinderpalsingh]

bump

found this document on wootz steel

http://met.iisc.ernet.in/~rangu/text.pdf

and a good read

http://tms.org/pubs/journals/JOM/9809/Verhoeven-9809.html

http://www.ias.ac.in/resonance/june2006/p67-77.pdf

[savinderpalsingh]

Replication of wootz

Replication of Wootz "Damascus" Type Steel

Greg Obach

Advisor: Dr. P. Julig

April 14 2003

Antr 4095

Abstract

In recent years, the Damascus steel making process is once again being examined in an effort to understand more about the striking patterns on ancient Damascus blades. Wootz is generally manufactured by the forging of a dendritic crucible steel. It is during the forging process and the associated heat treatments that the two phases of a wootz blade become pronounced. Information on the production of crucible steel is available, yet very little is known about the hammer forging techniques, or the cutting edge durability of the steel. In order to understand more about the effects of hammer techniques, a wootz crucible steel was produced and forged using several methods of fullering to draw out bar lengths. Metallographic studies of the test specimen’s longitudinal face, and transverse face are characterized in the experiment. The replication of ancient blade bevels is obtained by the comparison of two knife edge making methods. Edge durability of the replicated wootz blade is tested in a similar fashion to the American blade smith standards for knife edges.

Acknowledgements

I am ever thankful to Diane and Tom Obach for the encouragement and support while I was immersed in this project. I’d like to thank John Anderson and Rio Tinto Iron and Titanium Inc for providing the high quality cast iron used in making good wootz steel. I’m also extremely grateful to the people at Sudbury branch of RHI Canada Inc., who were very helpful to me. RHI products were used in the design of an outstanding crucible furnace. I am especially thankful to my supervisor, Dr. Patrick Julig, for his patience, support, and expert knowledge in the field of Archaeology.

Table Of Contents

Page

Abstract…………………………………………………………………... I

Acknowledgements………………………………………………………. II

Table of Contents………………………………………………………… III

List of Figures……………………………………………………………. IV

Chapter I : Introduction……………………………………………….. 1

Chapter II : Experimental Method…………………………………….. 4

Chapter III : Results……………………………………………………. 16

Chapter IV : Discussion………………………………………………... 22

References Cited…………………………………………………………. 25

List Of Figures

Page

Figure 1. Iron Carbon Phase diagram …………………………… 13

Figure 2. Proper ingot morphology ……………………………... 14

Figure 3. Maintaining Convex shape ……………………………. 14

Figure 4. Fullering Diagram …………………………………….. 14

Figure 5. Radius edges Diagram…………………………………. 15

Figure 6. Blade profile …………………………………………... 15

Figure 7. Forging the tang ……………………………………….. 15

Figure 8. Wootz Ingot …………………………………………….16

Figure 9. Surface Dendrites……………………………………….17

Figure 10. Hammer planished blade spine …..……………………. 18

Figure 11. Medium fullered blade spine …………………………...18

Figure 12. Aggressively fullered blade spine………………………19

Figure 13. Hammer forged blade bevel…………………………….19

Figure 14. Ground blade bevel……………………………………..

Introduction

The development of steel has been a major factor in the history of human conquest, and which civilizations won out (Diamond, 1997). The sword has been an outstanding weapon, being thoroughly recorded in historical literature and poetry. Legends are sometimes made of Sword arms and the soldiers that carried them in conflicts. The Crusades brought back accounts of the Orientals carrying sharp swords made of wavy blue steel. European blade smiths tried desperately to replicate the steel and it’s properties but were largely frustrated in their attempts. Robert Breant in 1824 published his attempt at making this type of steel. The steel was highly carbureted and would crumble under the hammer when not forged properly (Breant, 1824). Al Kindi, Al Bairuni, and Al Tarsoussi have contributed treatises about Damascus blades but little has been recorded about the forging process (Zaki, 1953). The information the Arab philosophers have written characterizes the varieties of Damascus blades and their significances. Rarely has the forging procedure been mentioned in any of the published accounts of ancient "Wootz" Damascus. It is the goal of this study to replicate and understand more about the forging of the Damascus type steel called "Wootz".

Wootz Damascus can be described as a slowly cooled crucible steel with a carbon content of 1-2.1% (Wadsworth, 1980). " The inner structure of the steel is created when the molten charge begins to solidify and impurity elements such as Mn, S, Si, and P are the first elements to form a network by segregating between the austenite dendrites. The dendrites are deformed into planar arrays parallel to the blade surface during the forging procedure. The surface patterns are created when the preferred precipitation of cementite particles from the austenite form along the planar arrays during the thermomechanical treatment of hammer forging" (Verhoeven et al., 1993). In this statement, Verhoeven et al. have characterized the hidden properties of "Wootz" steel but there is still some research to be done on the third elements (Mn, S, Si, P) and the mechanisms for pattern formation.

The ancient smiths made "Wootz" steel for many of the utility items that were required in everyday life. The steel was traded as cakes from many regions and was forged in several countries such a Persia, India, Russia, and others (Gilmour and Allan, 2001). The method of Wootz manufacture was generally the carbonization of iron in a clay/rice husk crucible (Lowe, 1990). Within the clay crucible, the iron and carbon charge is enclosed by a lid and left to melt over a long period of time. Later the iron cake was released from the crucible after it was slowly cooled to a solid. Now the steel ingot was placed back in the fire and left to anneal till the smith was satisfied with it’s gray color and uniform surface mottlings (Massalski, 1841). Once the color of the ingot met the Blade smith’s demands it was forged into a watered steel sword. It is the endeavor of this study to help shed some light on the "Wootz" Damascus steel making process and characterize the forging procedure. The core of the experiment will be the actual replication of the steel and the forging of blades. Blades made from the steel are further tested for physical properties and visual characteristics. A brief comparison will be made with literature descriptions of "Wootz" blades and the surface characteristics.

The experiment in making and forging "Wootz" steel ingots was done by The Writer at his home. The blacksmith shop was a small 10 by 12 foot forge area with the standard equipment found in a very basic smithy. Tooling for the blacksmith shop was generally an anvil, coal forge, many different size hammers, and tongs to hold the hot steel ingot while forging to shape. The crucible furnace was home built out of a 45 gallon barrel for the purpose of manufacturing "Wootz" ingots. Plastic refractory bricks were used to line the inner core of the barrel and a large propane burner supplied the heat for melting the ingredients. Clay graphite crucibles were purchased and used to contain the ingredients of the steel melt.

Experimental Method

This section explains a method in which the "Damascus type" crucible steel was produced for the experiment and the testing of the steel visually and functionally. This general overview of the smelting process is followed by an in depth explanation of the hammering and forging of the ingot material, to produce a "Wootz" Damascus type steel blade. This section will then be followed by actual results of the steel and the blades produced.

Producing the Wootz Ingot

1) A crucible furnace powered by propane gas was built and used to

generate the heat energy needed to reach the melting point (1535 cel.) of

iron.

2)The ingot of steel consisted of 1010 iron and a high carbon cast iron that were added together in the right proportions to attain a mixture of 1.5% carbon. The individual components within the steel were selected to be within the typical range of genuine Damascus sword (Verhoeven 1993:189), as listed below.

C % Mn % Si % S % P % Cu % Cr% Ni %

1.34-1.87 .005-.14 .005-.11 .007-.038 .05-.206 .04-.06 trace .008-.016

3) The charge was put into a "A6" clay graphite crucible and covered

with a cup of green glass.

4)The charge was then heated to liquidus within 40 to 90 minutes

followed by a "ramp down" temperature. The charge was not left to boil

for any length of time due to the possibility that extra carbon would be

absorbed from the crucible. The furnace temperature was lowered in such

a manner as to cool the liquid steel to solidus in a slow fashion. The

general cool down time was within 10 to 20 minutes of the initial

temperature ramp down.

5)The furnace burner was then closed when the charge was at a solid state

and left to cool in the furnace.

6)After 6 hours, the charge was removed from the crucible and cleaned of

the fluxing glass (Figure 8.). The color of the wootz cake is noted. If a

very brassy appearance is present, this could indicate that the carbon

content is too high. The over carburization of the ingot will turn the steel

into cast iron and render it virtually impossible to forge. The wootz cake

was then examined for dendritic patterns on the surface of the steel. The

dendrites are a key sign of the quality of a wootz ingot. The dendritic

strings of cementite nodules are a noticeable feature of surface

morphology on the ingot (Figure 9.).

7) The wootz cake is then put into a steel crucible filled with iron oxide scale. The crucible is then lowered into the furnace at the temperature of 1100 celsius and allowed to slowly cool 5 to 10 hours. This procedure was to produce a low carbon steel rim around the high carbon steel inner core before hammer forging. The thermal treatment also helps to anneal the product and produce a finer microstructure in the ingot.

8) The wootz cake is then removed from the crucible and examined for a

decarburized and ductile iron shell or rim surrounding the charge. The appearance of the wootz cake will now have a very dull and mottled gray surface color.

10) The cake is now ready to be forged into blade shapes.

Forging the Damascus Type Blade

Now that a wootz cake has been sufficiently processed and prepared, it is

possible to begin forging test blades to shape. Several methods of forging

are tested to try and reproduce the similar internal structures and surface

"waterings" reported in genuine damask swords.

1)Three rectangular bar blanks are forged to similar blade lengths.

2) The individual bars are forged using different degrees of "fullering".

Fullering is a method of deformation to draw out a length of steel by hammering a small depression in the barstock with a specially shaped hammer, and then flattening out the whole surface of the metal (Figure. 4).

3) The first bar is fullered using a very aggressive angle and flattened with

an 8 lb hammer.

4) The second bar is fullered with medium sized fuller and flattened with

an 8 to 12 lb hammer.

5) The third bar is drawn out with a round faced hammer (a very mild

form of fullering).

6)The very thin soft iron rim produced from the iron oxide anneal is now

removed from the outer surface of the blade blanks by using a high speed

belt grinder. The end section of the blade is cut transversely to examine the

inner grain structure. The surface of the wootz billets is then sanded with

emery cloth from 80 to 1500 grit to produce a very smooth area for the

ferric chloride etch. The etch is used to reaffirm that the dendritic pattern

of the wootz steel is present.

7) Once the blanks have been ground properly, a brief (20 second) ferric

chloride etch is applied to the surface, and the surface lightly cleaned and neutralized in baking soda. The knife surface is immediately oiled to prevent oxidation of the blade.

8) Each blade is then examined visually and recorded in a 6x

photograph. The results visually compared with the micrograph preformed by Verhoeven (1987:156) and Peterson (1990:362). The cementite banding and the angles of sheeting are the main objectives of the observation and comparison in the experiment.

Two Damascus Forged Blade edges

In the previous section, two blade blanks are forged from a wootz cake. The two blanks are then used to make a comparison between a forge blade edge and a "stock reduced" or ground blade edge. The process is to better understand the morphology and metallurgy of the blade edges and try to learn which methods may have been used in antiquity to produce such edges.

1) The first blade blank is forged into a rectangular billet.

2) The decarburized rim is then ground off the billet.

3) The bevel of the blade edge is now stock reduced into the profile by

the use of a belt grinder.

4) The second blade blank is processed differently in the forging stage.

The blade bevel on this blank is forged into place at a similar angle to the stock reduced bevel of the first blade.

5) The second blade is ground to remove the decarburized rim around

the billet.

6) The blade is heated to critical temperature (cherry red in color and

non magnetic) and quenched in a light oil. A temper is drawn to a brown gold surface oxide color on the surface of the blade, by re-heating the blades in an electric oven.

7) Both blades are sanded with fine grit abrasives in order to provide an

acceptable surface for the final ferric chloride etch.

8) Ferric chloride is used to reveal the banding on the beveled blade

edges of the two billets. The banding is observed on both blades and compared to the edge micrographs of genuine Damascus blades.

Blade Edge Durability of Damascus steel

To test the cutting ability of wootz Damascus steel, the blades are then evaluated with a similar test to the American Blade Smith standards for knives.

1) The first test is called the rope cutting test. A free hanging hemp rope of 1 inch in diameter is hung from a secure overhead fixture. The rope is then struck with the cutting edge of the blade, 6 inches from the free hanging end. Successfully cutting through the rope indicates good edge geometry and sharpness of the blades.

2) The second test is a wood chopping test. The wood was spruce purchased from the local hardware store. A construction grade 2 inch by 4 inch softwood board length is struck with the blade edge of the knives. The board must be cut twice and then an examination of the edge is performed. The test demonstrates edge toughness of the forged blade.

3) The last test demonstrates edge retention. The sections of the blade used in the previous test must be able to shave hair to show that enough of the edge remains keen and shaving sharp.

Detailed Hammer Forging Procedure of "Damascus Type" Blades.

1) In this section an indepth procedure of the hammer forging process is presented, as considerable skill and precision is needed to avoid many potential forging errors. The goal of forging the ingot is to produce a square bar from which a blade profile can be made. Potential errors may occur when wootz is initially forged at a cooler temperature or allowing the formation of improper ingot morphology. Initial temperatures below an orange color may result in the formation of cracks in the steel. Caution must also be taken not to forge the ingot in a bright yellow color or the steel will also deteriorate. The forged ingot must remain in a continuous and fattened (convex outer profile) shape avoiding the formation of an hourglass ingot profile (Figure 2.) The hour glass profile will lead to severe cracking and de-laminations.

2) The first step is to begin heating the ingot with the face towards the coal fire at the proper temperature. The proper temperature to heat the ingot is determined by comparing the ingot material to the Iron-carbon phase diagram in Figure 1 (Verhoeven. Jones, 1987). The ingot is held at the specific temperature, between Acm and A1, making sure that the blackbody radiation is uniform over the whole surface. The temperature must never exceed Acm or else severe cracking will occur. It is important to heat the ingot on the perpendicular sides to the ingot face that will be forged. The ingot remains in the forge for a holding period of 7 minutes to ensure that the core of the steel is sufficiently heated. The holding period generally depends on the size of the ingot. After the holding period has expired, the ingot is withdrawn from the forge to the anvil with a pair of blacksmith tongs and hammered with an 8 to 12 lbs sledge hammer.

3) Figure 3 shows the techniques and corrections needed to form a good ingot shape. Once the ingot has been shaped into a square billet, it can now be drawn out into a long bar length appropriate for a sword or blade profile. To draw out the square billet, the steel is now fullered and flattened in the direction of forging. The fuller in this experiment was preformed by 3 different shaping methods as follows :

A) "planishing" with hammer face – only the hammer face is used to draw out the bar length. The hammer face has only a very mild curvature.

B) medium fuller- a medium face used to dimple the steel prior to being flattened out with a flat hammer face, as in Figure 4(b). The circular medium fuller face is 13.5 mm in diameter of curvature.

C) aggressive fuller- a sharper hammer face used to dimple and depress the steel prior to being flattened out with a flat hammer face. The circular aggressive fuller face is 7 mm in diameter of curvature.

Figure 4. is a visual illustration of how the hammer is employed in properly drawing out the billet. In forging the billet it was found that maintaining a bar length that has radius or rounded edges was important, as shown in Fig 5.

In order to reduce the chances of forming a wrinkle or initiating a crack, it is critical to maintain a square or slightly rounded bar shape during the entire drawing-out process. During the forge cycle it is also very important to heat the bar length from a temp near Acm 1 down to a low red color prior to beginning another heating cycle. "Heat cycling" the bar length in this manner apparently promotes the creation of the best surface waterings. The surface patterns or "waterings" is an important aspect of "Wootz" steel.

Once the bar is of appropriate length to form a sword, it must then be profiled into the blade shape, prior to working on forging the blade bevels. The bar length is heated on the profile side then removed from the fire to form the tip on the blade edge. It is important to hammer on the blade edge only when the bar length is hot. After shaping on the profile, immediately correct any wrinkles that occur on the side of the blade edge by hammering them out. (See Figure 6 for an in depth illustration of the hammer techniques and processes.)

It is now prudent to begin forging the tang of the blade. Hammer the tang profile only when the steel is sufficiently hot and quickly correct any wrinkles on the side of the steel, as shown on Figure 7. Once these steps are finished you may forge in the blade bevels in a standard manner used by most bladesmiths. The blade bevels are forged into place by holding the blade at an appropriate angle to the anvil surface. The edge is now hammered into place by a similarly angled hammer strikes to the blade. The edge is forged into both sides with an even amount of hammer blows, making sure to overlap all the strikes.

4) The steel is now ready to be quenched in an medium weight oil bath. The piece is heated in the coal fire evenly over

the blade surface till it reaches a non-magnetic state (cherry red color).

After the color is evenly distributed on the steel, it is quenched

vertically into a barrel of light warm oil. The blade remains in the

quench till it is cool to the touch, and then removed for cleaning.

Cleaning the oil and oxides off of the blade surface is important

before proceeding to the next step, the tempering of the steel.

5) The bare steel blade is now ready to be tempered in an oven.

Generally the oven is set at 350 degrees Fahrenheit and the blade

remains in the oven till a yellow brown oxide color is visible over the

entire blade length. Once the temper is even colored, the blade is

quickly removed from the oven to prevent further softening of the

blade edge. It is also advisable to further draw a purple or blue temper

color over the tang/handle of the blade, to further soften the steel. The blue temper will reduce brittleness and prevent breakage of the tang during heavy use.

6) The knife is now ready to be hand sanded to a mirror finish, and then

etched with nitric acid or ferric chloride. The knife is repeatedly dipped into a 4% solution of ferric chloride and distilled water, till a dark pattern is revealed. The oxide is then removed by a light grinding compound on a felt buffing wheel. The cycle is repeated until the desired surface watering is displayed on the blade.

Figure. 1.

Results

Wootz Ingot Morphology

A primary characteristic in the production of Wootz crucible steel is the dendritic patterns displayed on the surface of the steel ingot. The dendritic pattern in the ingots results from microstructural distribution of cementite and impurity elements (Verhoeven, and Jones 1987). The following pictures seen in Figures. 8-9. display the profile and surface dendritic patterns achieved in the experiment. The steel ingots produced in the experiment on average weigh 6 lbs. The ingots have a height of 6.5cm and a width of 9.5 cm, resulting from the A6 crucible size used.

Figure. 8. Side view of an ingot from A6 crucible

In Figure. 9. a magnified picture of the ingot surface is shown and the dendritic pattern is seen. It is this coarse dendritic network that after forging, ultimately leads to the visible surface markings on the Damascus swords (Sherby, Wadsworth 1985).

Figure 9. Surface Dendrite displayed on top of ingot, 6X magnification,

after removal of glass flux.

Planar Sheeting and forging observations

The results of the three different hammer forging processes explained in the experimental methods section are noted and photographed. The alignment of the planar sheets is recorded on the longitudinal face of the blade spine by the linear direction of the cementite particles. The cementite particles are made visible by a selective etching process.

In Figure 10, as the result of very mild fullering, the longitudinal section of a hammer planished blade is shown. The planar sheeting and cementite particles on the spine of the blade visibly exhibit a relatively linear orientation and an apparent direction parallel to the longitudinal face.

Figure 10. Etched longitudinal face of blade 1. Hammer planished and treated with ferric chloride. The spine is observed under a 6x magnification.

The second blade specimen was hammer forged using a medium fuller to draw out the ingot. All three examples were derived from the material of one large ingot. The blade in Figure 11 shows a mild curvature or "s" pattern in the cementite particles visible on the spine and is visibly more wavy than the previous example. The overall direction is still roughly parallel to the longitudinal face with some visible curvature to the planar orientation.

Figure 11. Etched longitudinal face of blade 2. Hammer forged with a medium fuller and etched with ferric chloride. The spine is observed under a 6x magnification

The third wootz blade seen in Figure 12 was forged using a more "aggressive" fuller. The aggressive fuller draws out the ingot into bar length in a rapid fashion. On the visible longitudinal face, the cementite particles in the planar sheeting are aligned in a very aggressive and chaotic "s" pattern. The direction of orientation is still parallel to the longitudinal face but recorded in more of a meandering pattern. This method seems to provide a closer approximation to the reported Damascus type steel. The longitudinal etch is very similar in morphology to the Damascus blade characterized by Peterson et al. (1990).

Figure 12. Etched longitudinal face of blade 3. Hammer forged with an aggressive fuller and etched with ferric chloride. The spine is observed under 6x magnification.

Edge Morphology and Watered Patterns

Two methods of forming the edge on a Damascus blade are characterized in this portion of the results. One method of forming the blade edge is to hammer forge the bevel angles and edges during the process of shaping the overall blade. The second method of producing a blade edge is to grind the bevel angle with an abrasive stone or modern belt grinder on the profile of the blade.

The first edge to be characterized is the hammer forged edge seen in Figure 13.

Figure 13. Nitric acid etched blade, hammer forged bevel on blade edge, 2x magnification.

The second edge is shown in Figure 14. displaying an edge morphology that has been ground into the Damascus blade. The ground blade edge can be observed in the top portion (1/5 th) of the blade seen in Figure 14. In this example the wavy "watered steel" is absent near the edge where the blade was ground.

Figure 14. Nitric acid etched blade, ground bevel edge, 2x magnification.

The two pictures provide the possible patterns observed by the methods employed when reconstructing the edges of ancient Damascus type blades.

Cutting Edge Durability of Wootz

The beginning of this section is devoted to testing the edge retention and cutting ability of a wootz knife blade. The first test is the ability of a knife to cut through a free hanging 1-inch hemp rope. The process of edge testing used is similar to the test detailed by the American Bladesmith Journeyman exam. The exam information is further explained on the http://www.americanbladesmith.com/ABS_JSTest.htm website.

The knife used in this test was a wootz bowie knife forged out of similar steel to the prior test pieces. The bowie knife had an edge ground onto the bevel with a 600 grit aluminum oxide paper and sanding block. Once proper technique was used, the knife was able to cut through the rope on 3 occasions.

On the second part of the second part of the test, the blade was used to chop through a spruce 2 inch by 4-inch board length twice. The edge test was performed three times and showed no signs of a chipped or compacted blade edge. The blade carried no visible damage from the previous tests.

The final test was to shave hair, showing that the keen edge has remained intact through the previous tests. The knife remained largely sharp on the vast majority of it’s surface and could shave hair. The hammered bevel blades performed the tests with the same results as the ground in edge knives.

Discussion

The experiment involving the planar sheeting and hammer forging was performed to better understand the relationship between these two aspects of wootz blades. It was known that the dendritic (Wootz) steel aligns in clustered sheets of cementite (Verhoeven, Pendray, Berge 1993). The distinct waviness in the cementite sheeting was thought to have been created when the bladesmith used a fullering tool to draw the steel out into blade length (Peterson, Baker, Verhoeven 1990). If the method of forging was recorded in the waviness of the planar sheeting, ancient blades could provide some of the missing details of the old hammer forging techniques. Experimentation with different forging techniques on modern materials and a comparison between both ancient and modern blades could provide some of the forging information. The results of the experiment shown in Figures 10-12. indicate that the pattern of waviness does increase with the aggressiveness of the hammer or fullering technique. The first test piece of "Wootz" Damascus type steel was forged with the flat face of a hammer (Figure 10). The flat method of hammer forging is a very slow manner in which to draw the steel out to bar length. The method is recorded in the planar sheeting is the direction and shape of the cementite particles, which are very flat and linear, oriented towards the blade tip and tang. The distinctive waviness of "Wootz" Damascus type steel is lacking.

The second wootz blade was forged using a medium fuller (Figure 11). The medium fuller is a mild method by which to draw the steel out into bar length. Planar sheeting in the spine of the 2^nd wootz blade showed a very gradual "s" shape cementite pattern, somewhat indicative of the "Wootz" pattern.

The third blade was aggressively fullered and drew out to bar length in a quick manner (Figure 12). The cementite particles were still oriented towards the blade tip and tang but showed a chaotic or meandering "s" shaped morphology. A similar distinct waviness is described by Peterson et al. (1990) in the characterization of an ancient "Wootz" Damascus steel sword.

Upon examining the three blades it can be shown that the method of fullering is recorded to a degree in the planar sheeting. Understanding this principle can shed some light on the forging methods used by bladesmiths on ancient wootz swords. The methods and techniques used by ancient smith’s to forge wootz are rare and lack detail. The only publication where the forging particulars are mentioned was by J. Abbot made in Jullalabad (Piaskowski, 1978).

In addition to the previous experiments, two more blades were produced to look at the relationship between a hammer forged bevel for the blade edge or a ground/stock reduced blade edge. The hammer forged bevel was produced while "hot forging" the knife and a side profile is shown in Figure 13. It is clear to see that the surface waterings on the knife are similar on the blade bevel and the broad flat of the profile. The second blade was forged to near completion with a rather thick edge. The edge was then ground to a sharp bevel with the use of a high speed belt grinder. After the edge bevel was ground into the knife, it was then etched to show the carbide pattern. Figure 14. displays the side profile of the knife, with the top 1/5 of the blade representing the ground edge. A definite change in blade waterings and pattern morphology has occurred with the ground knife edge. The edge shows a pattern resembling the sheeting pattern spine on the knife and not the large, long and flowing pattern on the side of the blade. It is possible from the experiment to determine whether the ancient bladesmiths used either method to create the edge on ancient blades.

The third part in the examination of replicated wootz steel blades, a cutting test was performed on the blade edge. The blade was used to cut a free hanging hemp rope and chop through a 2 by 4 inch pine board. The wootz blade edge was observed for compaction or chipping. The edge showed very little disparity or damage after the tests were completed. The test is a good example of the durability and function of the knife during normal use of a blade. The tests were performed with both a ground edge on the knife and a forged bevel. The different blades performed with very similar outcomes through out the process of edge testing.

References Cited

American Bladesmith Society

2000 ABS Performance Test: Journeyman Smith Applicant. Electronic

document, http://www.americanbladesmith.com/ABS_JSTest.htm,

accessed October 15, 2002.

Breant, M.

1824 Description of a Process for making Damasked Steel. Annals of

Philosophy 8: 267-271.

Diamond, J.

1997 Guns, Germs, and Steel: The Fates of Human Societies. W. W.

Norton and Company.

Gilmour, B., and Allan, W. J.

2001 Persian Steel: The Tanavoli Collection. Oxford University Press.

Lowe, T. L.

1990 Solidification and the Crucible Processing of Decanni Ancient Steel.

Principles of Solidification and Materials processing: Proceedings of

Indo-US workshops. Trans Tech Publications.

Massalski

1841 Preparation de l’acier damasse en Perse. Annuaire du Journal des

Mines de Russie, pp.297-308.

Peterson, D T. Baker, H H. and Verhoeven, J D.

1990 Damascus Steel, Characterization of One Damascus Steel Sword.

Materials Characterization 24: 355-374.

Piaskowski, J.

1978 Metallographic examination of Two Damascene Steel Blades. The

Journal For The History Of Arabic Science 1: 3-30

Verhoeven, J D. and Jones, L L.

1987 Damascus steel, Part 2: Origin of the Damask Pattern.

Metallography 20:153-180.

Verhoeven, J D. and Pendray, A H.

1993 Studies of Damascus steel blades: part1 Experiments of Reconstructed blades. Materials Characterization 30: 175-186.

Verhoeven, J D. Pendray, A H. and Berge, P M.

1993 Studies of Damascus Steel Blades: Part2 Destruction and

Reformation of the Pattern. Materials Characterization 30: 187-200.

Verhoeven, J D. and Jones, L L.

1987 Damascus steel, Part2: Origin of the Damask Pattern.

Metallography 20: 153-180.

Voigt, A F. and Abu Samra, A.

1965 Analysis of a Damascus steel by Neutron and Gamma Activation.

International Conference: Modern Trends in Activation Analysis,

College Station, Texas 22-25.

Wadsworth, J. and Sherby, Oleg D.

1985 Damascus Steels. Scientific American 252(2): 112-120.

Wadsworth, J. and Sherby, Oleg D.

1979 On The Bulat- Damascus Steels revisited. Progress In Material

Science 25: 35-68.

Zaki, A R.

1953 Islamic Swords in Middle Ages. Bulletin de l’Institut d’Egypte 36:

365-379.

Wootz Steel (True Damascus)

Details of the blade of a Kurdish dagger (mountings early 20th Century), cut down from a Persian

shamshir

, signed

Kalb Ali

(dated middle to late 18th Century) A

60kb jpeg close-up

of this blade may also be viewed to more clearly see the Mohammed's ladder pattern.

These blades are directly forged from a small cake of heterogeneous steely iron which traditionally was produced in India. The steel, which is called

wootz

, was produced by heating iron ore, charcoal, and vegetable matter in a crucible for a prolonged period of time. This would produce a fairly high carbon steel, indeed sufficiently high carbon that special handling was necessary in forging the blade if fractures were to be avoided. The above close-up of such a blade shows a wavy pattern of shiny and dark steel. These patterns are made up of networks of steel showing different metallographic structures (globular cementite in a matrix of pearlite per

Maryon (1960)

) and extend through the full thickness of the blade.

J.D. Verhoeven, et. al. (1998)

propose that carbide forming trace impurities in the source ore and special forging and heat treatment techniques are necessary to preserve and enhance the pattern. The pattern is exposed when final grinding occurs and the natural heterogeneity of the steel is exposed. Customers for sword blades in the Middle East reputedly particularly valued a type of pattern referred to as

kirk narduban

or the ladder of the Prophet. In the close-up photograph above, you can see several "rungs" of such a ladder which are alterations in the background pattern running perpendicular to the length of the blade. While many explanations have been put forth in the literature for how this was difficult to achieve, a simple solution discovered by modern bladesmiths is that such a pattern is achievable by the mechanical manipulation of filing notches into the incomplete blade perpendicular to its length at regular intervals before final forging; essentially the same technique by which activity can be added to the

pamor

of the Javanese

keris,

again producing an alteration analogous to geographical contour lines.

WOOTZ STEEL: AN ADVANCED MATERIAL OF THE ANCIENT WORLD

Updated November, 18th 2000

Texte de :

S. Srinivasan and S. Ranganathan
Department of Metallurgy
Indian Institute of Science
Bangalore

You will be able to find the address of the original text in my link pages( G.E.)

Abstract

The development of ancient Indian wootz steel is reviewed. 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 the steel from the southern part of the Indian subcontinent was exported to Europe, China, the Arab world and the Middle East.

Though an ancient material, wootz steel also fulfills the description of an advanced material, since it is an ultra-high carbon steel exhibiting properties such as superplasticity and high impact hardness and held sway over a millennium in three continents- a feat unlikely to be surpassed by advanced materials of the current era.

Wootz deserves a place in the annals of western science due to the stimulus provided by the study of this material in the 18th and 19th centuries to modern metallurgical advances, not only in the metallurgy of iron and steel, but also to the development of physical metallurgy in general and metallography in particular.

Some of the recent experiments in studying wootz by re-constructing composition, microstructure and mechanical behaviour, along with some recent archaeological evidence, are described.

Wootz, High-carbon Steel, South India, Superplasticity, Crucibles, Analyses

1. Introduction

India has been reputed for its iron and steel since ancient times. Literary accounts indicate that steel from southern India was rated as some of the finest in the world and was traded over ancient Europe, China, the Arab world and the Middle East. Studies on wootz indicate that it was an ultra-high carbon steel with 1-2% carbon and was believed to have been used to fashion the Damascus blades with a watered steel pattern. Wootz steel also spurred developments in modern metallographic studies and also qualifies as an advanced material in modern terminology since such steels are shown to exhibit super-plastic properties. This paper reviews some of these developments.

2. History of wootz steel

There are numerous early literary references to steel from India from Mediterranean sources including one from the time of Alexander (3rd c. BC) who was said to have been presented with 100 talents of Indian steel, mentioned by Pant [1]. Bronson[2] has summarised several accounts of the reputation of Indian iron and steel in Greek and Roman sources which suggest the export of high quality iron and steel from ancient India. Srinivasan [3], Biswas [4] and Srinivasan and Griffiths [5] have pointed out that the archaeological evidence from the region of Tamil Nadu suggests that the Indian crucible steel process is likely to have started before the Christian era from that region. Zaky [6] pointed out that it was the Arabs who took ingots of wootz steel to Damascus following which a thriving industry developed there for making weapons and armour of this steel, the renown of which has given the steel its name. In the 12th century the Arab Edrisi mentioned that the Hindus excelled in the manufacture of iron and that it was impossible to find anything to surpass the edge from Indian steel, and he also mentioned that the Indians had workshops where the most famous sabres in the world were forged, while other Arab records mention the excellence of Hinduwani or Indian steel as discussed by Egerton [7].

Several European travellers including Francis Buchanan [8] and Voysey [9] from the 17th century onwards observed the manufacture of steel in south India by a crucible process at several locales including Mysore, Malabar and Golconda. By the late 1600's shipments running into tens of thousands of wootz ingots were traded from the Coromandel coast to Persia. This indicates that the production of wootz steel was almost on an industrial scale in what was still an activity predating the Industrial Revolution in Europe.

Indeed the word wootz is a corruption of the word for steel ukku in many south Indian languages. Indian wootz ingots are believed to have been used to forge Oriental Damascus swords which were reputed to cut even gauze kerchiefs and were found to be of a very high carbon content of 1.5-2.0% and the best of these were believed to have been made from Indian steel in Persia and Damascus according to Smith [10]. Some of the finest swords and artefacts of Damascus steel seen in museums today are from the Ottoman region i.e. Turkey.

In India till the 19th century swords and daggers of wootz steel were made at centres including Lahore, Amritsar, Agra, Jaipur, Gwalior, Tanjore, Mysore, Golconda etc. although none of these centres survive today. Different types of Damascus sword patterns have been identified, described in some depth by Pant [1], who also identified a new design from blades kept in the collection of the Salar Jung Museum in Hyderabad.

It may be mentioned however that the term Damascus steel can refer to two different types of artefacts, one of which is the true Damascus steel which is a high carbon alloy with a texture originating from the etched crystalline structure, and the other is a composite structure made by welding together iron and steel to give a visible pattern on the surface. Although both were referred to as Damascus steels, Smith [11] has clarified that the true Damascus steels were not replicated in Europe until 1821.

3. Role of wootz steel in the development of modern metallurgy

The legends associated with the excellent properties of the wootz steel and the beautiful patterns on Damascus blades caught the imagination of European scientists in the 17th-19th centuries since the use of high-carbon iron alloys was not really known previously in Europe and hence played an important role in the development of modern metallurgy. British, French and Russian metallography developed largely due to the quest to document this structure. Similarly the textured Damascus steel was one of the earliest materials to be examined by the microstructure. Smith [10, 11] has fascinatingly elucidated this early historiography of the interest in the study of wootz steel and its significance to the growth of metallurgy.

Although align="justify"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 the Swedish chemist Tobern Bergman, and was due to the efforts of Europeans to unravel the mysteries of wootz. Tobern Bergman was able to determine that the compositions of cast iron, steel and wrought iron varied due to the composition of "plumbago" i.e. graphite or carbon. As suggested by Smith [11] the Swedish studies received an impetus following the setting up of a factory to make gun barrels of welded Damascus steels, and it was on observation of the black and white etching of the steel and iron parts that a Swede metallurgist guessed that there was carbon in steel, and interest in replicating true Damascus steels followed.

In the early 1800's, following the descriptions of crucible steel making in south India by the European travellers, there was a spurt in interest in Europe in investigating south Indian wootz steel, from which the fabled Damascus blades were known to be made, with the aim of reproducing it on an industrial scale. Mushet's [12] studies in 1804 were one of the first to correctly conclude that there was more carbon in wootz than in steel from England, although this idea did not gain currency until later. Michael Faraday [13], the inventor of electricity and one of the greatest of the early experimenters and material scientists, as pointed out by Peter Day [14], was also fascinated by wootz steel and enthusiastically studied it. Along with the cutler Stodart, Faraday attempted to study how to make Damascus steel and they incorrectly concluded that aluminium oxide and silica additions contributed to the properties of the steel and their studies were published in 1820 [15]. They also attempted to make steel by alloying nickel and noble metals like platinum and silver and indeed Faraday's studies did show that that the addition of noble metals hardens steel. Stodart [16] reported that wootz steel had a very fine cutting edge.

Following this the interest in Damascus steel moved to France. Wadsworth and Sherby [17] have pointed out that Faraday's research made a big impact in France where steel research on weapons thrived in the Napoleonic period. The struggle to characterize the nature of wootz steel is well reflected in the efforts of Breant [18]in the 1820's from the Paris mint who conducted an astonishing number of about 300 experiments adding a range of elements ranging from platinum, gold. silver, copper, tin, zinc, lead, bismuth, manganese, arsenic, boron and even uranium, before he finally also came to the conclusion that the properties of Damascus steel were due to "carburetted" steel. Smith [10] has indicated that the analysis of ingots of wootz steel made in the 1800's showed them to have over 1.3% carbon. The Russian Anasoff [19] also studied the process of manufacturing wootz steel and succeeded in making blades of Damascus steel by the early 1800's.

In the early 1900's wootz steel continued to be studied as a special material and its properties were better understood as discussed further in the next section. Belaiew[20] reported that blades of such steel to cut a gauze handkerchief in midair. In 1912, Robert Hadfield [21] who studied crucible steel from Sri Lanka recorded that Indian wootz steel was far superior to that previously produced in Europe. Indeed in the 18th-19th century special steels were produced in Europe as crucible steels, as discussed by Barraclough [22].

4. Investigations of superplasticity and other mechanical properties of wootz steel

Some European scientists were successful in replicating and forging wootz and Stodart who used it in his cutlery business found that wootz steel had a superior cutting edge to any other, while Zschokke in 1924 found that with heat treatment this steel had special properties such as higher hardness, strength and ductility, mentioned by Smith [10]. By 1918 an important finding concerning Damascus steel was made by Belaiew [20] who was probably the first to attribute the malleability of Damascus steel to the globulitic (i.e. spheroidised) nature of the forged steel and to recognize that this occurs during forging at a temperature of red heat (i.e. 700-800 ⁰ C).

Panseri [23] in the 1960's was one of the first to point out that Damascus steel was a hypereutectoid ferrocarbon alloy with spheroidised carbides and carbon content between 1.2-1.8%. Recent studies have indicated that ultra-high carbon steels exhibit superplastic properties. As pointed out by Wadsworth and Sherby[17], by 1975 Stanford University had found that steels with 1-2.1% C i.e. ultrahigh carbon steels could be both superplastic at warm temperatures and strong and ductile at room temperatures. It was only subsequently that it came to the authors notice that these steels were in fact similar in carbon content to the Damascus steels.

Superplasticity is a phenomenon whereby an elongation of several hundred percent can be observed in certain alloys in tension, with neck free elongations and without fracture. By contrast most crystalline materials can be stretched to no more than 50-100 per cent. Superplasticity occurs at high temperatures and superplastic materials can be formed into complex shapes. For superplastic materials the index of strain rate sensitivity (m) is high, being around 0.5. At ideal m=1 flow stress is proportional to strain rate and the material behaves like a Newtonian viscous fluid such as hot glass. Superplasticity occurs only above 0.3-0.4 Tm K where Tm is the melting point. Another feature is that once super-plastic flow is initiated the flow stress required to maintain it is very low. Superplastic material essentially comprises of a two-phase material of spherical grains of extremely fine grain size of not more than 5 microns at the working temperature. Such ultrafine grained materials exhibit grain boundary sliding yielding superplastic properties.

Contemporary studies by Wadsworth and Sherby [17] and Sherby [24] indicated that UHCS (i.e. ultra-high carbon steels) with 1.8% C showed a strain-rate sensitivity exponent nearing 0.5 at around 750^° C suggesting that Damascus steel could well have exhibited superplastic properties and a patent was awarded for the manufacture of such UHCS.

The explanation of the superplasticity of the steel is that the typical microstructure of ultra-high carbon steel with the coarse network of pro-eutectoid cementite forming along the grain boundaries of prior austenite, can lead to a fine uniform distribution of spheroidised cementite particles (0.1 m m diam.) in a fine grained ferrite matrix. This spheroidisation of cementite is described in Wadsworth and Sherby [17], Sherby [24] and Ghose et al. [25]. Such steels are also found to have strength, hardness and wear resistance.

Such steels had to be forged, however, in a narrow range of 850-650^° C and not at the white heat of 1200^° C to get the desired fine grain structure and plasticity. In fact as pointed out in an appraisal of Indian crucible steel making by Rao [26], and in a review of ancient iron and steel in India by Biswas [4], the early European blacksmiths failed to duplicate Damascus blades because they were in the practice of forging only low carbon steels at white heat, which have a higher melting point. Biswas [4] mentions that the forging of wootz at high heat would have led to the dissolution of the cementite phase in austenite so that the steels were found to be brittle enough to crumble under the hammer.

Moreover, attractive combinations of strength and ductility were found to be achieved by Wadsworth and Sherby [17] and Sherby [24] when the ultra-high carbon steels were in spheroidised conditions with high yield strengths varying from 800 Mpa to 1500 Mpa with increasing fineness of spheroidised carbides, while the steel with coarsely spheroidised carbides was especially ductile with up to 23% tensile elongation.

While it is not yet known how fully the superplastic or superformable properties of this steel were exploited by the ancient blacksmiths of West Asia and India, accounts indicate that they were certainly able to manipulate the alloy with a skill that could not be easily replicated by the European experimenters of the 19th century. Indeed the swords of Damascus steel were reported to have high strength and ductility. Nevertheless, whereas the links between the patterns on the traditional Damascus blades and the crystalline structure of ultra-high carbon steels have been better established, the mechanical properties of the traditional Damascus blades and the degree of exploitation of the unique properties of the steel are less well understood.

Verhoeven [27] and Verhoeven et al. [28, 29] have attempted to "re-invent" the Damascus steel and blades as it were with replication experiments based on historical studies of Damascus blades and composition of wootz ingots. Verhoeven et al. [29] used two methods by which the ingots were made, one of which consisted of melting iron charge in a small sealed clay graphite crucible inside a gas-fired furnace with the ingot formed by furnace cooling. These were made by rapidly heating the charge and holding it for a period of 20-40 minutes between 1440^° C-1480^° C followed by cooling at furnace cooling rates or faster. The composition of the charge was chosen to match that of genuine Damascus blades of about 1.6% C and 0.1% P. However the fairly high level of phosphorus made the blades very hot short and difficult to forge. To overcome this problem the ingots were held at 1200^° C in iron oxide to produce a protective rim of pure iron around the ingot which was ductile so that the ingot could be forged. Ingots were also made with the phosphorus levels reduced to the point where the ingots were not hot short which eliminated the need for the rim heat treatment. Verhoeven et al.[29] also made ingots by a process of vacuum-induced melting whereby the charge was melted by heating to around 1000^° C, backfilling with nitrogen gas, heating to about 1580^° C and then outgassing for around 5 minutes so that cooling rates at arrest temperature were around 5-10⁰ C/minute.

It may be commented however, that although the structures of the ingots so produced do simulate those of Damascus blades, the methods used by Verhoeven et al. [29] are not strictly experimental re-constructions of the traditional processes, but rather laboratory simulations of the process, since the methods used do not really replicate conditions related to traditional or archaeological processes. For instance the charge is fired in both the methods described above in a very short time and the melt is cooled very rapidly under modern industrial conditions which could not have been achieved traditionally, while the 19th century descriptions of the wootz process suggest a very long firing cycle for the charge. In fact the eye witness descriptions of Voysey [8] and Buchanan [9] lay emphasis on the fact that the prolonged heating of the charge and its slow cooling were essential for obtaining the optimum results in the wootz process.

However the experimental simulations by Verhoeven et al. [29] served to monitor in detail the thermal cycles and cooling curves and composition so as to be able to arrive at a final product which matched that of Damascus blades and to understand the mechanism of formation of the pattern of aligned bands on the blades, which is reported by them to be produced by a carbide banding mechanism which was found to be assisted by the addition of P, S along with V, Cr, and Ti. Moreover their experiments are amongst the few comprensive studies on the general process of manufacture of the ingots themselves.

5. Archaeological and analytical evidence

Some of the archaeological and analytical evidence for crucible steel production is discussed covering the investigations of Rao [30], Rao et al. [31], Lowe [32, 33], Srinivasan [3] and Srinivasan and Griffiths [5]. These indicate that the crucible processes for steel production were spread over large parts of south India. Lowe's investigations have concentrated mainly on surveying and studying numerous sites from the Hyderabad region or the Deccani crucible steel process while pioneering investigations by Rao et al. [31] have covered other parts of south India such as the Mysore region and Salem district of Tamil Nadu. Field and analytical investigations were made by Srinivasan in 1990, whereby she was able to identify some hitherto unreported sites of crucible steel production in South Arcot, Tamil Nadu and from Gulbarga, Karnataka, reported in Srinivasan [3] and Srinivasan and Griffiths [5].

Srinivasan [3] has pointed out that whereas the process documented by Lowe [32,33], the Hyderabadi or Deccani process, involved the co-fusion of cast iron with wrought iron, the crucibles from sites reported by Srinivasan from Tamil Nadu and Karnataka pertained to the carburisation of wrought iron in crucibles by packing it with carbonaceous material. Analytical investigations made by Rao et al [30], Lowe[32, 33], Srinivasan [3], Craddock [34] and Srinivasan and Griffiths [5] on crucibles from production sites are briefly summarized.

The details of the furnace described and sketched by Buchanan [8] indicate that crucibles were packed in rows of about fifteen inside a sunken pit filled with ash to constitute the furnace which was operated by bellows of the buffalo hide, fixed into a perforated wall which separated them from the furnace probably to minimize fire hazards. The fire was stoked from a circular pit which was connected to the bottom of the ash pit. The crucibles themselves were conical and could contain up to 14 oz. of iron, along with stems and leaves. The wootz steel process in general refers to a closed crucible process and Lowe [32] has remarked that the processing of plant and mineral materials in closed crucibles is often described in Indian alchemical Sanskrit texts of the 7th-13th c. AD.

Investigations by Craddock [34] indicated the wootz ingot itself had a dendritic cast structure. Lowe [32, 33] has investigated particularly well the refractory nature of the crucibles of the crucibles which indicate that they were robust enough refractories to withstand the long firing cycles of up to 24 hours for the process. The formation of mullite and cryistobalite was detected in the crucible fragments studied by Lowe [32, 33] suggesting they had been well fired to high temperatures of over 1300-1400° C, while Rao et al [31] also observed the formation of mullite and cryistobalite in crucibles.

However the microstructures investigated by Lowe [32] of the metal remnants within the particular Deccani crucibles studied by her from Konasamudram could only be related to a failed process of crucible steel production at that particular site or context since they related more to white cast iron, a brittle and not very malleable material formed by over-carburisation, rather than ultra-high carbon steel. In fact based on these findings Lowe [32] has preferred to cautiously aver that it was a white cast iron ingot that was produced by the Indian crucible process. Craddock [34] has also opined that the product of the Indian crucible steel process was probably a general homogenous steel rather than specifically a high-carbon steel.

On the other hand investigations by Srinivasan [3] and Srinivasan and Griffiths [5]indicated the presence of solidified metal droplets in the crucibles with a typical micro-structure and micro-hardness corresponding to a good quality hypereutectoid steel with the formation of hexagonal grains of prior austenite with fine lamellar pearlite within the grains, with the precipitation of pro-eutectoid cementite along the grain boundaries of prior austenite: which is in fact the classic structure of ultra-high carbon steels of about 1.5% C which were made under laboratory conditions by Wadsworth and Sherby [17] and Verhoeven et al. [29]. The findings reported in Srinivasan [3] and Srinivasan and Griffiths [5] are hence significant in that they prove beyond doubt that high-carbon steels were indeed made by crucible processes in south India. Studies by Srinivasan and Griffiths [5] also indicated that temperatures of over 1400^° C had indeed been reached inside the crucibles to melt the wrought iron and carburise it to get a molten high-carbon steel with the typical hypereutectoid structure on solidification.

Conclusions

The above review indicates that the reputation of wootz steel as an exceptional and novel material is one that has endured from early history right into the present day, with the story of the endeavours to study it in recent history being nearly as intriguing as the story of its past. The archaeological findings indicate that crucible steel does have an ancient history in the Indian subcontinent where it took roots as suggested by literary references, while the analytical investigations indicate that a high-grade ultra-high carbon steel was indeed produced by crucible processes in south India. Recent investigations on the properties of the ultra-high carbon wootz steel such as superplasticity justify it being called an advanced material of the ancient world with not merely a past but also perhaps a future.

Acknowledgements

The authors would like to acknowledge the Indian National Academy of Engineering. Srinivasan would like to acknowledge the support of British Council, New Delhi for a British Chevening Scholarship for doctoral research, and the interest of Dr. D. Griffiths, Institute of Archaeology, University College London, Dr. J. A. Charles, Cambridge University, late Dr. C. V. Seshadri, founder-President, Congress of Traditional Science and Technology, and Hutti Gold Mines Ltd. for assistance with fieldwork and the support of the Homi Bhabha Research Council.

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27. J. D. Verhoeven, Damascus steel, Part I: Indian Wootz Steel, Metallography20 (1987), pp. 145-51.
28. J. D. Verhoeven, H. H. Baker, D. T. Peterson, H. F. Clark and W. M. Yater, Damascus Steel, Part III: The Wadsworth-Sherby mechanism, Materials Characterization, 24 (1990), pp. 205-27.
29. J. D. Verhoeven, A. H. Pendray, and E. D. Gibson, Wootz Damascus Steel Blades, Materials Characterization 37 (1996), pp. 9-22.
30. K. N. P. Rao, Wootz-Indian Crucible Steel, Feature Article. No.1, Metal News,11 , (1989), pp. 1-6.
31. K. N. P Rao, J. K. Mukherjee, and A. K. Lahiri, Some observations on the structure of ancient steel from south India and its mode of production, Bulletin of Historical Metallurgy, 4, (1970), pp. 12-4.
32. T. L. Lowe, Solidification and the crucible processing of Deccani ancient steel. In Trivedi, R., Sekhar, J. A. and Mazumdar, J. (Eds.), Principles of Solidification and Materials Processing, Oxford and IBH Publishing, New Delhi, Vol. 2, (1989),pp. 639-739.
33. T. L. Lowe, Refractories in high-carbon iron processing: a preliminary study of Deccani wootz-making crucibles, In Kingery, W. D. (ed.), Ceramics and Civilization, The American Ceramic Society, Pittsburgh, 4 (1990), pp. 237-50.
34. P. T. Craddock, Early Metal Mining and Production, Edinburgh University Press, Edinburgh (19

RESONANCE ç June 2006 67

GENERAL ç ARTICLE

A Tale of Wootz Steel

S Ranganathan and Sharada Srinivasan

Wootz steel, Damascus swords,

Cyril Stanley Smith.

The extraordinary romance and thrilling adventure associated with the tale of wootz steel shows how Indian metallurgists were the world leaders in antiquity in the manufacture

of this legendary high-grade steel. In many ways this material was brought to global attention by the writings of Cyril

Stanley Smith. Modern metallurgy and materials science

rest on the foundation built by the study of this steel during

the past three centuries.

1. Introduction

Wootz steel was highly prized across several regions of the world

over nearly two millennia and the products made of this Indian

steel came to be known as Damascus swords. Figure 1 shows a

splendid example of the sword of Tipu Sultan. It is no exaggeration to state that wootz steel as an advanced material dominated

several landscapes: the geographic landscape spanning the continents of Asia, Europe and the Americas; the historic landscape

stretching over two millennia as maps of nations were redrawn

and kingdoms rose and fell; the literary landscape as celebrated

in myths and legends, poetry and drama, movies and plays; the

linguistic landscape of Sanskrit, Arabic, Urdu, Japanese, Tamil,

Telugu and Kannada. It held sway over the religious landscape

through trade and other interactions of Hinduism, Buddhism,

Zoroastrianism, Judaism, Islam and Christianity. This is unique

as no other advanced material can display this mutifaceted

splendour.

The development of wootz steel by sheer empirical practice in

Southern India, the fashioning of the steel by thermo-mechanical treatments to fierce and beautiful Damascus Swords in India

and the Middle East with little knowledge of the underpinning

science is a remarkable tale in the annals of metallurgy. When

S Ranganathan is a Visiting

Professor at the School of

Humanities, Nationl

Institute of Advanced

Studies, Banglaore. His

area of interest is the

interaction between

materials and society.

Sharada Srinivasan is a

faculty fellow at the

National Institute of

Advanced Studies,

Bangalore. Her areas of

interest include

archaeometallurgy , art

and performing arts.68 RESONANCE ç June 2006

GENERAL ç ARTICLE

Figure 1. Sword of Tipu

Sultan.

this steel was presented to the Western world, scientists in

England, France, Russia and Sweden toiled hard and discovered

the composition and microstructure and their relation to mechanical properties. This single-minded pursuit of an Eastern

technological product by Western scientists for over a century

created the foundations of modern materials science. Cyril Stanley

Smith has emphasized this theme in his writings. In addition

there is a possible connection with nanomaterials and computer

modeling. Thus the investigations on wootz steel continue to

inspire researchers to this day.

2. Iron and Steel Heritage of India

India has been reputed for its iron and steel since ancient times.

The Delhi Iron Pillar is a marvellous monument. There are

numerous early literary references to steel from India from

Mediterranean sources including one from the time of Alexander

(3rd c. BC), who was said to have been presented with 100 talents

of Indian steel. Arabs took ingots of wootz steel to Damascus

following which a thriving industry developed there for making

weapons and armour of this steel, the renown of which has given

the steel its name. In the 12th century the Arab Edrisi mentioned that the Hindus excelled in the manufacture of iron and

that it was impossible to find anything to surpass the edge from

Indian steel. The famous novel ìThe Talismanî by Sir Walter

Scott narrates the encounter between King Richard of England,

known as Lion Heart and Sultan Saladin during the third

crusade. Though this 1825 account is fictional, it is evident that

the fame of the swords made out of wootz steel spread to Europe,

when the crusaders encountered them at Damascus. One possible origin for the term Damascus swords is traced to this

encounter. In 1912, Robert Hadfield who studied crucible steel

from Sri Lanka recorded that Indian wootz steel was far superior

to that previously produced in Europe.

It is ironic that not too many records are available documenting

the process of wootz production. It is mainly the European

travelers who left detailed accounts. These include FrancisRESONANCE ç June 2006 69

GENERAL ç ARTICLE

Buchanan in 1807, Benjmain Heyne in 1818, H W Voysey in

1832 and Josiah Marshall Heath in 1840. They observed the

manufacture of steel in south India by a crucible process at

several locales including Mysore, Malabar and Golconda. By the

late 1600ís shipments running into tens of thousands of wootz

ingots were traded from the Coromandel coast to Persia. This

indicates that the production of wootz steel was almost on an

industrial scale in what was still an activity predating the Industrial Revolution in Europe.

The word wootz is a corruption of the word ukku for steel in

many south Indian languages. Indian wootz ingots have been

used to forge Oriental Damascus swords which were reputed to

cut even gauze kerchiefs and were found to be of a very high

carbon content of 1.5-2.0% and the best of these were believed to

have been made from Indian steel in Persia and Damascus

according to Smith. In India till the 19th century swords and

daggers of wootz steel were made at centres including Lahore,

Amritsar, Agra, Jaipur, Gwalior, Tanjore, Mysore and Golconda,

although none of these centres survive today.

It may be mentioned however that the term Damascus steel can

refer to two different types of artefacts, one of which is the true

Damascus steel which is a high carbon alloy with a texture

originating from the etched crystalline structure, and the other

is a composite structure made by welding together iron and steel

to give a visible pattern on the surface. Although both were

referred to as Damascus steels, Smith has clarified that the true

Damascus steels were not replicated in Europe until 1821. The

pattern welded composite swords are the essence of the Samurai

and Viking.

3. The Role of Wootz Steel in the Development of

Modern Metallurgy

For centuries iron and steel were thought as being two elements

belonging to the ferrous family, just as copper, silver, gold and

other metals belong to the non-ferrous family of metals. The

Indeed chemistry

must in some degree

attribute its very

origins to iron and its

makers.

T A Wertime, 196170 RESONANCE ç June 2006

GENERAL ç ARTICLE

recognition that steel is an alloy of iron and carbon came as a

result of the chemical assaying of wootz steel in 1774 by the

Swedish chemist Tobern Bergman. He was able to determine

that the compositions of cast iron, steel and wrought iron varied

due to the composition of ëplumbagoí i.e. graphite or carbon. As

suggested by Smith, the Swedish studies received an impetus

following the setting up of a factory to make gun barrels of

welded Damascus steels, and it was on observation of the black

and white etching of the steel and iron parts that a Swede

metallurgist guessed that there was carbon in steel, and interest

in replicating true Damascus steels followed. The Chemical

Revolution wrought by Lavoisier received an impetus with the

identification of carbon as an element. Smith has argued that ìif

the practical man was rather too slow to benefit from the new

knowledge of chemistry that was being developed, he can feel

that his practical knowledge, by helping the identification of

carbon as an element, has contributed in a far from trivial way to

the Chemical Revolution itselfî.

As England had colonized India, there was considerable interest

in studying wootz steel. Michael Faraday, the inventor of electricity and one of the greatest of the early experimenters and

material scientists was also fascinated by wootz steel and enthusiastically studied it. Along with the cutler Stodart, Faraday

attempted to study how to make Damascus steel and they incorrectly concluded that aluminium oxide and silica additions

contributed to the properties of the steel and their studies were

published in 1820. They also attempted to make steel by alloying

nickel and noble metals like platinum and silver and indeed

Faradayís studies did show that that the addition of noble metals

hardens steel. Though Faraday failed to replicate the wootz

steel, he is hailed as the father of alloy steels.

Following this the interest in Damascus steel moved to France,

as Faradayís research made a big impact in France where steel

research on weapons thrived in the Napoleonic period. The

struggle to characterize the nature of wootz steel is well reflected

in the efforts of Breant in the 1820ís from the Paris mint. He

Designing a New

Material World

As the new millennium un-

folds, a confluence of natural

philosophies one that com-

bines reductionist and syn-

thetic thinking is ushering

in an Age of Design marked by

new materials and ways of cre-

ating them beyond the dreams

of the medieval alchemists.

The modern view of materials

structure was best expressed

by the late philosopher-scien-

tist Cyril Stanley Smith. He

described a universal multi-

level nature of structure with

strong interactions among lev-

els and an inevitable interplay

of perfection and imperfection

at all levels.

Gregory B Olson

Designing a New Material

World, Science,

Vol.288, p.993, 2000.RESONANCE ç June 2006 71

GENERAL ç ARTICLE

conducted an astonishing number of about 300 experiments

adding a range of elements ranging from platinum, gold. silver,

copper, tin, zinc, lead, bismuth, manganese, arsenic, boron and

even uranium, before he finally also came to the conclusion that

the properties of Damascus steel were due to ëcarburettedí steel.

Smith has indicated that the analysis of ingots of wootz steel

made in the 1800ís showed them to have over 1.3% carbon.

The Russian Anasoff also studied the process of manufacturing

wootz steel and succeeded in making blades of Damascus steel

by the early 1800ís. In the early 1900ís wootz steel continued to

be studied as a special material and its properties were better

understood as discussed further in the next section. Belaiew

reported that blades of such steel cut a gauze handkerchief in

midair.

As studies of wootz gained, it became imperative to establish the

phase diagram of iron-carbon system. The first comprehensive

construction is due to Roberts-Austen in 1898. This was the first

phase diagram of any alloy ever to be established. Such a diagram made it evident that it is possible to distinguish different

products such as wrought iron, plain carbon steels, ultra high

carbon steels and cast irons on the basis of their composition

(Figure 2) . It was also possible to identify various phases such as

Figure 2. Iron-carbon (Fe-

C) diagram (first phase dia-

gram of any alloy to be es-

tablished, by Roberts-

Austen in 1898 after whom

austenite came to be

named.).

Courtesy: J Wadsworth72 RESONANCE ç June 2006

GENERAL ç ARTICLE

Cyril Stanley Smith and Japanese Art and Metallurgy

Cyril Stanley Smith was fascinated by both Japanese art and metallurguy. He studied Samurai swords and

the Mokumé Gane process. The rich textures to be found in paintings and metallic artefacts were a source

of endless fascination for him.

Japanese swords have been highly acclaimed for their beautiful patterns owing to lamination techniques

of different grades of iron and steel resulting in visible heterogeneities and aesthetic patterns. Cyril

Stanley Smith effusively wrote that the best of all examples of a satisfactory art form based upon the inner

nature of a metal is provided by Japanese swords. The Japanese swords were often made by repeated

forging, welding and reforging of the sponge, alternate layers of high carbon and lower carbon steel as

many as 20 times which could have as many as 2

20

layers of metal. This would result in a visible texture

because the slag inherent to the metal would resist deformation in a different way from the ferrous regions,

giving an interesting gradient in the metallurgical texture. This would be aesthetically highlighted by the

minimalistic shaping of the sword.

Mokumé Gane a Japanese product is of relatively recent

origin. Mokumé literally means wood eye and gane means

metal. It refers to the visual appearance of the pattern in metal

approximating that of wood. It forms an interesting contrast

with the Damask texture discussed earlier. It was mainly in

vogue from the late sixteenth century to the middle of the

nineteenth century. Feudal Japan was obsessed with swords

and their decorations. The Mokumé Gane technique is attrib-

uted to Denbei Shoami (1651-1728), a master smith from Akita

prefecture. He combined copper with shakudo, an alloy of

copper with 4% gold, in the form of a laminate to create a form

similar to Chinese and Japanese lacquer work (Figure A). Several

tsubas have this type of origin (Figure B). Roberts-Austen, of the

Fe-C diagram fame, was fascinated by the Mokumé Gane. There

was one description, where there was a mistaken reference to

soldering various layers together for creating Mokumé Gane. This

led to failures by those who subsequently tried to recreate it, as

delamination occurred at the solder joint.

Japan gradually abandoned this product. In the early part of the

twentieth century interest in the west in these matters also waned.

Again, it was the intervention of C S Smith that led to a revival of

this subject. There are now more people in the USA working on

Mokumé Gane than there ever were in Japan! Essentially, solid

state diffusion is the key to processing dissimilar metals to come

together. Careful temperature control can be exercised in the

modern experiments.. Thus the ancient process has arisen, phoenix-

like, leading to a variety of laminates involving copper, gold, iron,

palladium, platinum and silver.

B. Sketch of Japanese tsuba

wrought iron guards for

the swords of the Samurai

warriors.

A. Mokumé Gane from JapanRESONANCE ç June 2006 73

GENERAL ç ARTICLE

austenite, ferrite, cementite. The phase reactions such as

peritectic, eutectic and eutectoid came to be established.

Combination of phases led to microstructures consisting

of pearlite and ledeburite. The use of the optical microscope became widespread due to studies of wootz steel.

Figure 3 shows the dendritic microstructure in wootz steel

as recorded by Smith.

4. Deformation and Solidification Microstructures

Panseri in the 1960ís was one of the first to point out that

Damascus steel was a hypereutectoid ferrocarbon alloy with

spheroidised carbides and carbon content between 1.2-1.8%.

Recent studies have indicated that ultra-high carbon steels

exhibit superplastic properties. Wadsworth and Sherby at

Stanford University had found that steels with 1-2.1% C i.e.

ultrahigh carbon steels could be both superplastic at warm

temperatures and strong and ductile at room temperatures. It

was only subsequently that it came to the authorsí notice that

these steels were in fact similar in carbon content to the Damascus steels.

Contemporary studies by Wadsworth and Sherby indicated

that UHCS (i.e. ultra-high carbon steels) with 1.8% C showed a

strain-rate sensitivity exponent nearing 0.5 at around 750

o

C

suggesting that Damascus steel could well have exhibited superplastic properties and a patent was awarded for the manufacture of such UHCS. The explanation of the superplasticity of

the steel is that the typical microstructure of ultra-high carbon

steel with the coarse network of pro-eutectoid cementite forming along the grain boundaries of prior austenite can lead to a

fine uniform distribution of spheroidised cementite particles

(0.1 mm diam.) in a fine grained ferrite matrix.

John Verhoeven and the blacksmith Alan Pendray collaborated

in the production of modern Damascus blades. Verhoeven has

proposed that minute amounts of vanadium were necessary to

lead to microsegregation and the formation of banded struc-

Figure 3. Dendrites in Wootz

Steel.74 RESONANCE ç June 2006

GENERAL ç ARTICLE

tures during subsequent processing. Figure 4 shows the banded

pattern visible to the naked eye. This texture and its beauty

added to the reputation of the Damascus swords.

5. Materials Science Tetrahedron and Wootz Steel

As discussed above, the investigations on wootz steel in 19th

century Europe led to the foundations of what we understand

today as the central paradigm of materials science. This is based

on the idea that the processing of a material leads to a structure,

which has a definite combination of properties. This set of

properties in turn defines the performance of the possible products that can be made out of these materials. Merton C Flemings

and Praveen Chaudhari captured these four defining ideas as the

four corners of a tetrahedron . It will be noted that no particular

material is mentioned. It applies equally well to metals, ceramics, polymers and composites. It is this powerful generalization

that has made materials science a powerful, pervasive and enduring concept. It applies to steel and sand, nylon and nickel, bone

and bronze. The past decade has added one more idea to this

quartet of the conceptual framework, namely modelling. As

processing, structure and properties become complex, it is possible for us to resort to modelling and simulation. Figure 5

represents the materials science hypertetrahedron for wootz

steel. Individual vertices represent processing, structure, properties, performance and modelling. The facets of the Buchanan

furnace, the iron-carbon diagram, the microstructure of dendrites in the as-cast state and spheroidised cementite in the

forged material, the superplastic elongation, and the Damascene

marks are displayed with emphasis on the strong interconnections among them.

Materials science came into being due to the investigations into

the properties of wootz steel. As it continued to evolve in the

latter half of twentieth century, it took an amazing turn. The

question was raised as to whether new materials are to be

discovered by experiments or whether it will be possible to

design them from first principles. Quantum mechanics offers

Figure 4. Ladder pattern

Courtesy J D VerhoevenRESONANCE ç June 2006 75

GENERAL ç ARTICLE

powerful insights into the structure and behaviour of atoms.

Will it not be possible simply to compute and design alloys

inside the computer? A major contributor to this field is Greg

Olson. He was deeply influenced by Smithís emphasis on the

principle of hierarchy in the structure of materials. He has

argued that as the new millennium unfolds, it is ushering in an

Age of Design marked by new materials that go beyond the

dreams of the medieval alchemists.

At the coarsest level, solidification is the chemical banding

visible in the Damascus swords. It is possible to employ thermodynamics to predict the structures at the 10 mm scale. This may

be called ìsolidification designî. At the next lower level of 1mm,

the structural changes that take place on heat treatment can be

modelled. These follow various phase transformations. This

may be termed as ì transformation designî. When size is further

Figure 5. Materials hyper-

tetrahedron for Wootz steel.76 RESONANCE ç June 2006

GENERAL ç ARTICLE

reduced to 0.1 mm scale, design enters the micro-mechanics

regime. Grain refining can lead to such small grain sizes. It is

possible to use continuum mechanics to follow the flow and

fracture of materials. The most exciting level is the next level ñ

the nanoscopic level. The realm of quantum design begins at the

electronic level ñ the finest level relevant to real materials. The

need for modelling and design is best appreciated, when it is

realized that the possible combinations of elements for making

alloys and compounds is truly enormous. It typically takes a

hundred million dollars over two decades to fully develop and

qualify a new material using the experimental approach.

Olson went on to found a company christened as QuesTek

Innovations. Successful examples from the Northwestern University efforts include a stainless steel bearing for space shuttle

applications, high strength, high-toughness steels for aircraft

landing gear and armour applications, and a new class of ultrahard steels for advanced gear and bearing applications. Of

immense interest to wootz steel is the Dragon-slayer Project.

Olson in a dramatic fashion enlisted freshman and upper class

design teams to use the most modern and sophisticated computational methods to recreate an ancient steel. As ancient Western literature is replete with dragons, it was felt that a sword

named Dragon-slayer would have maximum market appeal.

The mystique of the Samurai sword provided the inspiration, as

even five centuries ago these swords outperformed all other

swords. So the performance specification had to be comparable.

In addition, high temperature resistance was an added requirement, as the sword had to deal with fire-breathing dragons! In

terms of form for the weapon, a historical precedent of a patterned double-edged sword was to be the example. As a supernatural element is necessary in fighting such mythical beasts,

the iron had to be of extra-terrestrial origin. Meteoritic iron,

which came from the sky, was the natural primary ingredient.

This fusion of ancient legend and modern science proved successful. But it is important to note that in spite of the fanciful

tale, the underlying science was of the most advanced kind using

Suggested Reading

[1] C S Smith, A History of Metallography, University

Press, Chicago, 1960.

[2] C S Smith, A Search for

Structure, MIT Press, Cambridge, 1981.

[3] Sharada Srinivasan and S

Ranganathan, Indiaís Legendary Wootz Steel: An Advanced Material of the Ancient world, Tata Steel, 2004.

[4] R W Cahn, The Coming of

Materials Science, 2001.RESONANCE ç June 2006 77

GENERAL ç ARTICLE

powerful computation and sophisticated experimental techniques.

6. Conclusions

The reputation of wootz steel as an exceptional and novel material is one that has endured from early history right into the

present day, with the story of the endeavours to study it in recent

history being nearly as intriguing as the story of its past. Recent

investigations on the properties of the ultra-high carbon wootz

steel such as superplasticity justify it being called an advanced

material of the ancient world with not merely a past but also

perhaps a future. This account of wootz steel as a legendary

material derives its authority from the numerous writings of

Cyril Stanley Smith.

Address for Correspondence

S Ranganathan and Sharada

Srinivasan

School of Humanities

National Institute of

Advanced Studies

Bangalore 560 012, India

Email:

rangu@met.iisc.ernet.in

sharada@nias.iisc.ernet.in

To conclude, on a higher level, it is common these days to talk of the meeting of East and West, and such

contact is immensely fruitful. However, I feel, with Kipling, that it would be undesirable for the different

attitudes of mind that constitute understanding in our two parts of the world to ever merge. They are both

needed, just as the wave and

particle approaches to radia-

tion. The complementarity is

essential. They are valuable

diverse parts of a larger unity,

not to be averaged without

loss. A new level of under-

standing, incorporating but

not homogeneizing diversity,

must arise. Where better than

in India, with its background

of rich contributions to both

science and art, could the new

encompassing level of under-

standing arise?

Cyril Stanley Smith

Sangam: Meeting of East and West, Arts and Technology

Ms Yamini Krishnamurthy, a famous classical dancer, being

felicitated by Cyril Stanley Smith, Varanasi, December 1973.

[savinderpalsingh]

Damascene Technique in metal working

https://docs.google.com/file/d/0B00MCbMdQQAbdEk0T3NSRXloYWc/edit

another read

http://howiefirth.wordpress.com/2012/03/25/damascus-swords-had-vanadium-steel/

[savinderpalsingh]

Carbon nanotechnology in an 17th century Damascus sword

By Ed Yong | September 27, 2008 10:00 am

In medieval times, crusading Christian knights cut a swathe through the Middle East in an attempt to reclaim Jerusalem from the Muslims. The Muslims in turn cut through the invaders using a very special type of sword, which quickly gained a mythical reputation among the Europeans. These ‘Damascus blades‘ were extraordinarily strong, but still flexible enough to bend from hilt to tip. And they were reputedly so sharp that they could cleave a silk scarf floating to the ground, just as readily as a knight’s body.

They were superlative weapons that gave the Muslims a great advantage, and their blacksmiths carefully guarded the secret to their manufacture. The secret eventually died out in the eighteenth century and no European smith was able to fully reproduce their method.

Two years ago, Marianne Reibold and colleagues from the University of Dresden uncovered the extraordinary secret of Damascus steel – carbon nanotubes. The smiths of old were inadvertently using nanotechnology.

Damascus blades were forged from small cakes of steel from India called ‘wootz’. All steel is made by allowing iron with carbon to harden the resulting metal. The problem with steel manufacture is that high carbon contents of 1-2% certainly make the material harder, but also render it brittle. This is useless for sword steel since the blade would shatter upon impact with a shield or another sword. Wootz, with its especially high carbon content of about 1.5%, should have been useless for sword-making. Nonetheless, the resulting sabres showed a seemingly impossible combination of hardness and malleability.

Reibold’s team solved this paradox by analysing a Damascus sabre created by the famous blacksmith Assad Ullah in the seventeenth century, and graciously donated by the Berne Historical Museum in Switzerland. They dissolved part of the weapon in hydrochloric acid and studied it under an electron microscope. Amazingly, they found that the steel contained carbon nanotubes, each one just slightly larger than half a nanometre. Ten million could fit side by side on the head of a thumbtack.

Carbon nanotubes are cylinders made of hexagonally-arranged carbon atoms. They are among the strongest materials known and have great elasticity and tensile strength. In Reibold’s analysis, the nanotubes were protecting nanowires of cementite (Fe₃C), a hard and brittle compound formed by the iron and carbon of the steel. That is the answer to the steel’s special properties – it is a composite material at a nanometre level. The malleability of the carbon nanotubes makes up for the brittle nature of the cementite formed by the high-carbon wootz cakes.

It isn’t clear how ancient blacksmiths produced these nanotubes, but the researchers believe that the key to this process lay with small traces of metals in the wootz including vanadium, chromium, manganese, cobalt and nickel. Alternating hot and cold phases during manufacture caused these impurities to segregate out into planes. From there, they would have acted as catalysts for the formation of the carbon nanotubes, which in turn would have promoted the formation of the cementite nanowires. These structures formed along the planes set out by the impurities, explaining the characteristic wavy bands, or damask (see image at top), that patterns Damascus blades.

By gradually refining their blade-making skills, these blacksmiths of centuries past were using nanotechnology at least 400 years before it became the scientific buzzword of the twenty-first century. The ore used to produce wootz came from Indian mines that were depleted in the eighteenth century. As the particular combination of metal impurities became unavailable, the ability to manufacture Damascus swords was lost. Now, thanks to modern science, we may eventually be able how to replicate these superb weapons and more importantly, the unique steel they were shaped from.