True Combat Value of Wootz

Chris Evans · 24th November 2006, 12:27 AM

Hi Ann,

Quote:

Originally Posted by Ann Feuerbach

FYI, Personally, I have not come across any blades with Martensite.

Neither was I aware that they existed until that earlier post by GT Obach and also this paper by Verhoeven and Pendray, available here:

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

Quote:

would be interested in any metallurgical studies of antique blades that do have Martensite, so references please.

So would I, but apart from the above, unfortunately I cannot help. I hasten to reiterate that as far as Wootz is concerned, I am a beginner on a steep learning curve.

I imagine that there must have been attempts to quench harden, as opposed to work harden, Wootz blades because of the superior hardness/strength attainable, but we do know the problems associated with quenching hypereutectoid steels. Perhaps quenching from the lowest possible temperature, established empirically would have minimized the problems to an acceptable level. Maybe, by sheer chance every now and then they managed to turn out a martensitic blade that wasn't badly flawed and performed superbly; I just cannot see the ancients regularly turning out superb Martensitic Wootz blades - Just my thoughts as an informed layman on the subject.

If I may impose on you a little: What is the highest measured hardness of a historical blade that you are aware of? And how was it tested (Brinell, Rockwell, Vickers)?.

I suspect that herein resides the original question of this thread. If Wootz swords were not quench hardened, merely work hardened, then I very much doubt that they could have ever been able to cut through armour, never mind wrought iron chains. And as such, whilst serviceable, their legendary reputations must have been based on gross exaggerations.

Cheers
Chris

Ann Feuerbach · 24th November 2006, 02:22 PM

Quote:

Originally Posted by Chris Evans

Neither was I aware that they existed until that earlier post by GT Obach and also this paper by Verhoeven and Pendray, available here:
http://met.iisc.ernet.in/~rangu/text.pdf

Sorry to be a pain, but where in the book do they mention a historical crucible steel blade with martensite? I have had a look and can not find it. Plus is GT Orbach's one from replication or an historical object? I remember doing a survey of all known published historical crucible steel objects, and I do not remember any with martensite, but I could have missed it.

Rivkin, As far as I recall, the information of Anasof's experiments, published by Bogachev, does suggest that his processes were comparable to traditional crucible steel ingredients and processes.

Gt Obach · 24th November 2006, 04:41 PM

Hi

Metallographic examination of two damascene steel blades... by Jerzy Piaskowski... 1978

no mention of Martensite but sorbitic matrix...

SORBITE:

Structure of steel, resulting from the tempering of martensite. In a truly sorbitic structure, the cementite is completely dispersed in the matrix. The trend is to call this structure tempered martensite.

this can be confusing... because i don't know if people still use that term sorbite... .. i know the bladesmiths all call it tempered martensite..

Look on pg 9 in the " discussions "
-- the structure of both blades is very uniform along the whole of the cross-section. The measurements of hardness showed identical values for each of the swords which, in turn, points to the fact that the blades were subjected to quenching and tempering, according to the descriptions by J. Barker and Massalski, who travelled in the Near East.

so... .. I was wrong...... as their is some evidence.....

thank you...

Greg

another quote from the study..

" strips of carbides are visible to the naked eye on the blades surfaces and appear in the form of light coloured bands typical of the damascus pattern, whereas the dark background of this pattern forms a sorbitic matrix "

tsubame1 · 24th November 2006, 06:55 PM

Quote:

Originally Posted by Gt Obach

this can be confusing... because i don't know if people still use that term sorbite... .. i know the bladesmiths all call it tempered martensite.

You're right. Sorbite is martensite tempered at high temperatures (600°)
for quiet a long period and is known as tempered martensite.

Hereunder two exaples from my HD :

Typical structure of oil quenched martensite :

Sorbite (martensite quenched in oil and tempered at 600° C for 2 hours) :

Rivkin · 24th November 2006, 10:34 PM

Very interesting. I thought for example Anosov used graphite instead of traditional materials such as coal/wood. But taking in mind that I have no idea how smithing works, it well may be that I am saying that simple shocks the present in its ignorance

.

tsubame1 · 24th November 2006, 11:50 PM

Quote:

Originally Posted by Rivkin

I thought for example Anosov used graphite instead of traditional materials such as coal/wood.

Usually graphite is found in cast (pig) iron being connected with a too much
high carbon content (2,8%-3,8%). I wonder if the burning of graphite
in these experiments can be connected with transferring some carbon to
steel or simply because it achieve the needed temperature in a faster
way or it can hold such temperature longer (only supposing about these two
last properties of graphite).

Japanese smiths transfer carbon to the blade using vegetal fiber wrapping
in certain stages of the smithing. Might be that putting steel into a
burning graphite bed is intended to the same aim to compensate the
carbon loss during the smithing ? Are wootz/crucible steel blades
folded many times as the japanese ones, meaning a loss of carbon in the
process and so needing a trick to maintain high the carbon content ?

Chris Evans · 25th November 2006, 05:13 AM

Hi Ann,

Quote:

Originally Posted by Ann Feuerbach

Sorry to be a pain, but where in the book do they mention a historical crucible steel blade with martensite? I have had a look and can not find it. Plus is GT Orbach's one from replication or an historical object? I remember doing a survey of all known published historical crucible steel objects, and I do not remember any with martensite, but I could have missed it.

.

First I must thank Frank for his correction and the supplementary links.

I found that link late in the night and read it too hastily. The authors were most certainly not by V&P - My mistake, for which I apologize.

In my haste, I did not read the work in full, just did a global search for the words `quench' and `Martensite'. However, it appears to me that the author links the hardening of Wootz with quenching and tempering, but I add, none too clearly for me, especially when we get to Pg 87.

On page 29/90 under the heading of Steel Processing: Reference to Indians smiths quenching swords into banana trees and worse

Pg 86/90: Reference to work by Kochman and colleagues in which a historical blade was examined for microstructure and bits of Martensite were found. The full article can be read here:

http://www.crystalresearch.com/crt/ab40/905_a.pdf

I found it interesting that: a) Martensite was formed in the 1st place, as this usually requires quenching of some sort, b) that there appears to be little Cementite near the very edge and c) the rather obtuse angle of the edge, which suggests something or another.

Pg 87/90: Elaboration on the idea of high carbon Martensite decomposing.

Cheers
Chris

Ann Feuerbach · 25th November 2006, 02:07 PM

Thanks loads Chris for the link. I did not have a copy of the article.
Ok, let me add some more murkiness to the mud.....

From Samuel's Optical Microscopy of Carbon Steels, 1980, ASM, P 26-28.
"Sorbite....It was subsequently shown that these constituents often were merely fine lammellar pearlite, but unfortunatly the terms were also indiscriminately used to refer to tempered martensite. This duality or origin was in fact recognized in the original ISI definition......." The text goes on in detail (sorbite was named for Sorby if anyone is interested).

From what I gather, there is primary and secondary sorbite: Primary from the eutectoid transformation process (and perhaps very important for pattern discussion) and secondary sorbite which is tempered marteniste.

Now all that said, my brain hurts and I am no more the wise.

Gt Obach · 25th November 2006, 11:19 PM

Hi Ann

yes.. you are correct and note... that it seems that sorbite... is a confusing term.. ... due to it being used for both tempered martensite and pearlitic sorbite ...

i've read more that a couple times that its an old term that seems to be out of style...lol

I had to reread that study i quoted several times before i realized they were talking about tempered martensite...... the term sorbite had fooled me at first

you see... he mentions sorbite that is produced in the case of these two swords were made according to the Massalski and Barker accounts..... In the Massalski account ... this is definitely an oil quench and that would make martensite ...

if it was pearlitic sorbite... then you wouldn't need an oil quench nor a temper cycle afterwards....... just air cooling

Greg

Chris Evans · 26th November 2006, 03:58 AM

Hi Folks,

1. I am beginning to think that we are rapidly reaching an impasse because of a lack of what can be considered sufficient studies on enough samples to be representative of Wootz swords - Especially those that were more than just eye candy. Nevertheless, we can state with some confidence the following:

a) In the absence of new knowledge, the quench hardening of hypereutectoid (>0.8%C) Wootz would have presented the ancients with enough problems to render the process quite haphazard - Whilst it is conceivable that some smiths could consistently estimate the lowest Austenitization temperature by the colour of the heated steel, a bit too much heat and some of the carbides re-disolved leading to retained Austenite after quenching (very undesirable);

b) That whilst unquenched hypereutectoid Woots can be work-hardened, the hardness obtainable would have been insufficient to produce swords capable of cutting through armour, or for that matter, knives and tools (say woodworking or stone cutting) with a sufficiently keen/hard edge to be truly functional;

c) Quenching/tempering and the attendant superior qualities thus attainable were sufficiently well known in antiquity, for Indian and Middle Eastern smiths to ignore and be satisfied with the inferior alternatives; And

d) there are too many instances of quenching being mentioned in olden times.

2. Other thoughts on this matter:

Why are we concentrating on hypereutectoid Wootz and exclude hypoeutectoid (<0.8%C) as representative of the kind?

What I am getting at is that there is no real difficulty in obtaining excellent Martensitic steel from hypoeutectoid stock, and tempered Martensite is the preferred microstructure for a sword that cuts by impact.

If the Indians could reliable produce hypoeutectoid crucible steel then the problem of how to obtain truly great hardness&toughness disappears. I imagine that it may have even been possible to arrive at a hypoeutectoid steel by de-carburizing hypereutectoid crucible steel stock. At this point of my deliberations, the only real advantage that I can see for hypereutectoid Wootz, apart from appearance, is a lower melting point which facilitated the crucible reduction process.

Greg could be right, as per his posts elsewhere, that our current day definition of what constitutes Wootz is unreasonably narrow by restricting it to hypereutectoid steel. For example, Vehroheven&Pendray decided that one of the swords they studied was not Woots Damascus because it did not contain the expected carbides. Ands yet, the term Wootz is said to be the Anglicization of the Kannada word for steel (any steel or crucible steel?). Of course they added the appellation `Damascus' to their definition, but then why go looking for mechanical attributes that may have have been the property of swords exclusive to this definition?

I think that it is fairly safe to say that when ancient chroniclers recorded that some swords performed remarkable cutting feats, that they did not class them by their carbon content, rather their origin, and even that very broadly.

Cheers
Chris

Ann Feuerbach · 26th November 2006, 05:04 PM

Hi Chris,
You are right. I have been arguing that hypoeutectoid crucible steel (producing ferrite/pearlite banding pattern) should not been seen as inferior. I am SURE that both were made in the same workshop, and were in the furnace next to each other, to control a difference between >0.8% and <0.8% would have been difficult to control. I am sure that cast iron was occasionally made as well.

Also, when I did my PhD I found that only 18 blades had been studied, which is why I am trying to increase that "database". How can we base any theories on such a small sample base? Plus, where the sample was take on the blade is also a concern when it comes to microstructures etc.

Just a note to say that I am not against any quenching/tempering of ancient blades, just the lack of evidence, but as mentioned above, could be due to sampling.

24th November 2006, 04:41 PM	#3
Gt Obach Member Join Date: Mar 2005 Posts: 116	Hi Metallographic examination of two damascene steel blades... by Jerzy Piaskowski... 1978 no mention of Martensite but sorbitic matrix... SORBITE: Structure of steel, resulting from the tempering of martensite. In a truly sorbitic structure, the cementite is completely dispersed in the matrix. The trend is to call this structure tempered martensite. this can be confusing... because i don't know if people still use that term sorbite... .. i know the bladesmiths all call it tempered martensite.. Look on pg 9 in the " discussions " -- the structure of both blades is very uniform along the whole of the cross-section. The measurements of hardness showed identical values for each of the swords which, in turn, points to the fact that the blades were subjected to quenching and tempering, according to the descriptions by J. Barker and Massalski, who travelled in the Near East. so... .. I was wrong...... as their is some evidence..... thank you... Greg another quote from the study.. " strips of carbides are visible to the naked eye on the blades surfaces and appear in the form of light coloured bands typical of the damascus pattern, whereas the dark background of this pattern forms a sorbitic matrix " Last edited by Gt Obach; 24th November 2006 at 05:25 PM.

24th November 2006, 10:34 PM	#5
Rivkin Member Join Date: Dec 2004 Posts: 655	Very interesting. I thought for example Anosov used graphite instead of traditional materials such as coal/wood. But taking in mind that I have no idea how smithing works, it well may be that I am saying that simple shocks the present in its ignorance .

25th November 2006, 02:07 PM	#8
Ann Feuerbach Member Join Date: Feb 2005 Posts: 133	Thanks loads Chris for the link. I did not have a copy of the article. Ok, let me add some more murkiness to the mud..... From Samuel's Optical Microscopy of Carbon Steels, 1980, ASM, P 26-28. "Sorbite....It was subsequently shown that these constituents often were merely fine lammellar pearlite, but unfortunatly the terms were also indiscriminately used to refer to tempered martensite. This duality or origin was in fact recognized in the original ISI definition......." The text goes on in detail (sorbite was named for Sorby if anyone is interested). From what I gather, there is primary and secondary sorbite: Primary from the eutectoid transformation process (and perhaps very important for pattern discussion) and secondary sorbite which is tempered marteniste. Now all that said, my brain hurts and I am no more the wise.

25th November 2006, 11:19 PM	#9
Gt Obach Member Join Date: Mar 2005 Posts: 116	Hi Ann yes.. you are correct and note... that it seems that sorbite... is a confusing term.. ... due to it being used for both tempered martensite and pearlitic sorbite ... i've read more that a couple times that its an old term that seems to be out of style...lol I had to reread that study i quoted several times before i realized they were talking about tempered martensite...... the term sorbite had fooled me at first you see... he mentions sorbite that is produced in the case of these two swords were made according to the Massalski and Barker accounts..... In the Massalski account ... this is definitely an oil quench and that would make martensite ... if it was pearlitic sorbite... then you wouldn't need an oil quench nor a temper cycle afterwards....... just air cooling Greg

26th November 2006, 03:58 AM	#10
Chris Evans Member Join Date: Mar 2005 Location: Australia Posts: 685	Hi Folks, 1. I am beginning to think that we are rapidly reaching an impasse because of a lack of what can be considered sufficient studies on enough samples to be representative of Wootz swords - Especially those that were more than just eye candy. Nevertheless, we can state with some confidence the following: a) In the absence of new knowledge, the quench hardening of hypereutectoid (>0.8%C) Wootz would have presented the ancients with enough problems to render the process quite haphazard - Whilst it is conceivable that some smiths could consistently estimate the lowest Austenitization temperature by the colour of the heated steel, a bit too much heat and some of the carbides re-disolved leading to retained Austenite after quenching (very undesirable); b) That whilst unquenched hypereutectoid Woots can be work-hardened, the hardness obtainable would have been insufficient to produce swords capable of cutting through armour, or for that matter, knives and tools (say woodworking or stone cutting) with a sufficiently keen/hard edge to be truly functional; c) Quenching/tempering and the attendant superior qualities thus attainable were sufficiently well known in antiquity, for Indian and Middle Eastern smiths to ignore and be satisfied with the inferior alternatives; And d) there are too many instances of quenching being mentioned in olden times. 2. Other thoughts on this matter: Why are we concentrating on hypereutectoid Wootz and exclude hypoeutectoid (<0.8%C) as representative of the kind? What I am getting at is that there is no real difficulty in obtaining excellent Martensitic steel from hypoeutectoid stock, and tempered Martensite is the preferred microstructure for a sword that cuts by impact. If the Indians could reliable produce hypoeutectoid crucible steel then the problem of how to obtain truly great hardness&toughness disappears. I imagine that it may have even been possible to arrive at a hypoeutectoid steel by de-carburizing hypereutectoid crucible steel stock. At this point of my deliberations, the only real advantage that I can see for hypereutectoid Wootz, apart from appearance, is a lower melting point which facilitated the crucible reduction process. Greg could be right, as per his posts elsewhere, that our current day definition of what constitutes Wootz is unreasonably narrow by restricting it to hypereutectoid steel. For example, Vehroheven&Pendray decided that one of the swords they studied was not Woots Damascus because it did not contain the expected carbides. Ands yet, the term Wootz is said to be the Anglicization of the Kannada word for steel (any steel or crucible steel?). Of course they added the appellation `Damascus' to their definition, but then why go looking for mechanical attributes that may have have been the property of swords exclusive to this definition? I think that it is fairly safe to say that when ancient chroniclers recorded that some swords performed remarkable cutting feats, that they did not class them by their carbon content, rather their origin, and even that very broadly. Cheers Chris

26th November 2006, 05:04 PM	#11
Ann Feuerbach Member Join Date: Feb 2005 Posts: 133	Hi Chris, You are right. I have been arguing that hypoeutectoid crucible steel (producing ferrite/pearlite banding pattern) should not been seen as inferior. I am SURE that both were made in the same workshop, and were in the furnace next to each other, to control a difference between >0.8% and <0.8% would have been difficult to control. I am sure that cast iron was occasionally made as well. Also, when I did my PhD I found that only 18 blades had been studied, which is why I am trying to increase that "database". How can we base any theories on such a small sample base? Plus, where the sample was take on the blade is also a concern when it comes to microstructures etc. Just a note to say that I am not against any quenching/tempering of ancient blades, just the lack of evidence, but as mentioned above, could be due to sampling.