True Combat Value of Wootz

Chris Evans · 23rd November 2006, 01:52 PM

GT Obach and Ann,

I have been wondering about Martensitic (quench hardened) Wootz. I imagine that the practical difficulty would have been the avoidance of re-dissolving the iron carbides whilst Austenitizing and then upon quenching ending up with retained Austenite, as well as Martensite, which is a trait of high carbon steels and potentially disastrous to toughness.

I suppose that this could have been minimized by keeping the Asutenitizing temperature as low as possible, but in the absence of modern temperature measurement apparatus and knowing how to deal with the problem, I just cannot see how the ancients managed to get over it. Any thoughts?

Cheers
Chris

Ann Feuerbach · 23rd November 2006, 03:22 PM

FYI, Personally, I have not come across any blades with Martensite. I would be interested in any metallurgical studies of antique blades that do have Martensite, so references please.

Rivkin · 23rd November 2006, 05:04 PM

1. I could not agree more with the importance of smith's qualifications.
2. So do we move from wootz to "crucible damascus" or we stay with "wootz" ? I like wootz more - it is shorter.
3. The problem is also "what is wootz ?". For example, a lot of people do not believe that what Anosov made was anything similar (besides patterns) to traditional wootz.
4. While the subject is heavily obscured by myths and so on, it seems that comparison wootz vs. others were repeatedly made with different results (i.e. Anosov's bulat seemed to be of really high quality).

Ann Feuerbach · 23rd November 2006, 05:35 PM

FYI, I have held the blade that Anosov made for Faraday. It had a light sham-like pattern, however, the blade was overcleaned and that may be why the pattern was faint and only visable near the handle.

Rivkin · 23rd November 2006, 05:47 PM

The patterns - no problems. But is it true that their chemistry/structure is usually very different than the swords they were supposed to imitate ? Again, I guess you know this material, while I just read some papers, so I would really appreciate to be corrected here.

tsubame1 · 23rd November 2006, 05:48 PM

Quote:

Originally Posted by Ann Feuerbach

FYI, Personally, I have not come across any blades with Martensite. I would be interested in any metallurgical studies of antique blades that do have Martensite, so references please.

Hi Dr. Feuerbach.

NihonTo (japanese blades) have martensite. A very high quality work my Dr. Tatsuo Inoue
was online but it is now available only downloading it by my site here under the title "Tatsuo Inoue Swordsmithing file":

http://xoomer.alice.it/tsubame/ZZZZZZ_DOWNLOADS.htm

I believe that "Control of inclusions in japanese ancient iron and steelmaking"
(available in the same link) can be of some interest to you too...

Gt Obach · 23rd November 2006, 07:50 PM

Hi

retained austenite is alway a problem with high alloys... especially with chromium.. .. I know Achim made a wootz with stainless levels of Cr ... and he did maintain it was tough... so i don't know .... if you reach the temp for martensite finish ... you should have good conversion... that why i like to undercool my blades abit... (just me being paranoid )

with the martensitic wootz.... you don't have an extended soak time as you would with other high alloy steel... I just treat it as a plain carbon steel with a very short 4 min soak at non-mag... ... basically, i don't want the large macro carbides to go into solution... just the steel matrix..... i know its abit bizarre.... just the opposite of modern heat treatments for high alloy steels... in the modern case you want the carbides to be dissolved
-- take for example A2 .... with 5% Cr needs 30 to 45 min at 1750 to 1800F for proper heat treat....

-- if you think about it..... part of the forging of the barstock is the growth of these macro carbides........ basically dissolving little ones and adding to the big.. .... through all those heat cycles......... from a black heat up to orange etc

also....... alot of the pattern of wootz has to do with how slow the cool time is from liquid charge to solid.... and.... combined with the roast time (anneal ) afterwards.......both time and temperature ...

just my opinion

tsubame1 · 23rd November 2006, 11:00 PM

Can't find better words then the Ted Tenold's ones to describe the following pictures that shows the grouped martensite called "Nie" in japanese swords :

quote...

Nie is basically "spheroidal martensite" which are clumps of martensitic growth propogated by long high heat and maintained in a rapid agressive quench.

...unquote.

pictures by Keith Larman ( http://moderntosho.com ) :

close-close-close up :

Chris Evans · 24th November 2006, 12:35 AM

GT Obach,

Thanks for that information. I have no doubt that with modern pyrometry and metallurgical know-how, we can get around the problems of producing Martensitic Wootz that performs - After all, you obviously did, as amply demonstrated by that cutting through wrought iron.

However, the question remains whether the ancients could do the same and to answer this, we need historical samples.

Cheers
Chris

Gt Obach · 24th November 2006, 01:09 AM

Hi Chris

you got it
-- we really need to test more ancient samples..... ... despite the couple studies that were done... i still have hope for some good martensite structures.....(i've been optimistic about it for years...

there are a couple of accounts that talk about oil quenching... ( yes, i know words are not proof enough for either of us...but they are interesting to read. )

Massalski account : "When the blade has cooled, it is quenched in boiling hemp seed oil. Some armourers add a little grease and bone marrow. The wooden tub which contains the oil is sufficiently large for the blade to go in easily. The oil is heated by plunging two or three pieces of red hot iron into it. During this time the blade is given a heat between red and white hot, and then plunged into the bath. If it is a dagger it is held flat; if it is a sabre, it is quenched little by little, beginning by the end of the cutting edge, holding the latter toward the bath. This manoeuvre is repeated until the oil stops smoking, which proves that the blade has cooled. After quenching the blade is always soiled with burnt oil. This dirt is removed by heating it enough to set light to a piece of wood, and by rubbing with a rag from a bedsheet. It is at this time too that imperfections are corrected and the blade is straightened if it is out of true. After 5 or 6 heats the blade leaves the fire quite ready, i.e it then only has to be cleaned with sand, polished with emery and mottled by pickling in iron sulphate. "

I've got others just got to dig them up...

also... one last thing... I'm really not sure that the air quenched wootz would be able to cut a cannon chain... but i could be wrong..... it may cut flesh well but i'm not sure about the other... what i do know is that air cool wootz is much much harder to get a nice even etch on... ...

take care
Greg

Chris Evans · 24th November 2006, 01:22 AM

Hi Greg,

Many thanks for that account. It certainly cannot be ignored and is food for thought as it does support the case for Martensitic Wootz. Not being familiar with the author, when was it written?

As far as work hardened Pearlitic Wootz is concerned, my guess (based on modern similarly hardened products) is that the equivalent of 45Rc should be readily attainable. And this hardness level is that of many 19th century military sabres, so is quite serviceable, but not outstanding.

Cheers
Chris

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

.

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

23rd November 2006, 11:00 PM	#8
tsubame1 Member Join Date: May 2006 Location: Magenta, Northern Italy Posts: 123	Martensite Can't find better words then the Ted Tenold's ones to describe the following pictures that shows the grouped martensite called "Nie" in japanese swords : quote... Nie is basically "spheroidal martensite" which are clumps of martensitic growth propogated by long high heat and maintained in a rapid agressive quench. ...unquote. pictures by Keith Larman ( http://moderntosho.com ) : close-close-close up :

24th November 2006, 01:22 AM	#11
Chris Evans Member Join Date: Mar 2005 Location: Australia Posts: 685	Hi Greg, Many thanks for that account. It certainly cannot be ignored and is food for thought as it does support the case for Martensitic Wootz. Not being familiar with the author, when was it written? As far as work hardened Pearlitic Wootz is concerned, my guess (based on modern similarly hardened products) is that the equivalent of 45Rc should be readily attainable. And this hardness level is that of many 19th century military sabres, so is quite serviceable, but not outstanding. Cheers Chris Last edited by Chris Evans; 24th November 2006 at 02:43 AM.

24th November 2006, 04:41 PM	#14
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.

23rd November 2006, 01:52 PM	#1
Chris Evans Member Join Date: Mar 2005 Location: Australia Posts: 685	GT Obach and Ann, I have been wondering about Martensitic (quench hardened) Wootz. I imagine that the practical difficulty would have been the avoidance of re-dissolving the iron carbides whilst Austenitizing and then upon quenching ending up with retained Austenite, as well as Martensite, which is a trait of high carbon steels and potentially disastrous to toughness. I suppose that this could have been minimized by keeping the Asutenitizing temperature as low as possible, but in the absence of modern temperature measurement apparatus and knowing how to deal with the problem, I just cannot see how the ancients managed to get over it. Any thoughts? Cheers Chris

23rd November 2006, 03:22 PM	#2
Ann Feuerbach Member Join Date: Feb 2005 Posts: 133	FYI, Personally, I have not come across any blades with Martensite. I would be interested in any metallurgical studies of antique blades that do have Martensite, so references please.

23rd November 2006, 05:04 PM	#3
Rivkin Member Join Date: Dec 2004 Posts: 655	1. I could not agree more with the importance of smith's qualifications. 2. So do we move from wootz to "crucible damascus" or we stay with "wootz" ? I like wootz more - it is shorter. 3. The problem is also "what is wootz ?". For example, a lot of people do not believe that what Anosov made was anything similar (besides patterns) to traditional wootz. 4. While the subject is heavily obscured by myths and so on, it seems that comparison wootz vs. others were repeatedly made with different results (i.e. Anosov's bulat seemed to be of really high quality).

23rd November 2006, 05:35 PM	#4
Ann Feuerbach Member Join Date: Feb 2005 Posts: 133	FYI, I have held the blade that Anosov made for Faraday. It had a light sham-like pattern, however, the blade was overcleaned and that may be why the pattern was faint and only visable near the handle.

23rd November 2006, 05:47 PM	#5
Rivkin Member Join Date: Dec 2004 Posts: 655	The patterns - no problems. But is it true that their chemistry/structure is usually very different than the swords they were supposed to imitate ? Again, I guess you know this material, while I just read some papers, so I would really appreciate to be corrected here.

23rd November 2006, 07:50 PM	#7
Gt Obach Member Join Date: Mar 2005 Posts: 116	Hi retained austenite is alway a problem with high alloys... especially with chromium.. .. I know Achim made a wootz with stainless levels of Cr ... and he did maintain it was tough... so i don't know .... if you reach the temp for martensite finish ... you should have good conversion... that why i like to undercool my blades abit... (just me being paranoid ) with the martensitic wootz.... you don't have an extended soak time as you would with other high alloy steel... I just treat it as a plain carbon steel with a very short 4 min soak at non-mag... ... basically, i don't want the large macro carbides to go into solution... just the steel matrix..... i know its abit bizarre.... just the opposite of modern heat treatments for high alloy steels... in the modern case you want the carbides to be dissolved -- take for example A2 .... with 5% Cr needs 30 to 45 min at 1750 to 1800F for proper heat treat.... -- if you think about it..... part of the forging of the barstock is the growth of these macro carbides........ basically dissolving little ones and adding to the big.. .... through all those heat cycles......... from a black heat up to orange etc also....... alot of the pattern of wootz has to do with how slow the cool time is from liquid charge to solid.... and.... combined with the roast time (anneal ) afterwards.......both time and temperature ... just my opinion

24th November 2006, 12:35 AM	#9
Chris Evans Member Join Date: Mar 2005 Location: Australia Posts: 685	GT Obach, Thanks for that information. I have no doubt that with modern pyrometry and metallurgical know-how, we can get around the problems of producing Martensitic Wootz that performs - After all, you obviously did, as amply demonstrated by that cutting through wrought iron. However, the question remains whether the ancients could do the same and to answer this, we need historical samples. Cheers Chris

24th November 2006, 01:09 AM	#10
Gt Obach Member Join Date: Mar 2005 Posts: 116	Hi Chris you got it -- we really need to test more ancient samples..... ... despite the couple studies that were done... i still have hope for some good martensite structures.....(i've been optimistic about it for years... there are a couple of accounts that talk about oil quenching... ( yes, i know words are not proof enough for either of us...but they are interesting to read. ) Massalski account : "When the blade has cooled, it is quenched in boiling hemp seed oil. Some armourers add a little grease and bone marrow. The wooden tub which contains the oil is sufficiently large for the blade to go in easily. The oil is heated by plunging two or three pieces of red hot iron into it. During this time the blade is given a heat between red and white hot, and then plunged into the bath. If it is a dagger it is held flat; if it is a sabre, it is quenched little by little, beginning by the end of the cutting edge, holding the latter toward the bath. This manoeuvre is repeated until the oil stops smoking, which proves that the blade has cooled. After quenching the blade is always soiled with burnt oil. This dirt is removed by heating it enough to set light to a piece of wood, and by rubbing with a rag from a bedsheet. It is at this time too that imperfections are corrected and the blade is straightened if it is out of true. After 5 or 6 heats the blade leaves the fire quite ready, i.e it then only has to be cleaned with sand, polished with emery and mottled by pickling in iron sulphate. " I've got others just got to dig them up... also... one last thing... I'm really not sure that the air quenched wootz would be able to cut a cannon chain... but i could be wrong..... it may cut flesh well but i'm not sure about the other... what i do know is that air cool wootz is much much harder to get a nice even etch on... ... take care Greg

24th November 2006, 10:34 PM	#16
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	#18
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	#19
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