True Combat Value of Wootz

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

Marc · 24th November 2006, 11:35 AM

Just as a pointer...

Chris, the text in PDF you linked is not an article from Verhoeven and Pendray, but an extract (only the main text, without the figures, nor the frontpage, foreword and acknowledgements) of a book written by a couple of Bangalore (India) researchers, Dr. Sharada Srinivasan and Prof. Srinivasa Ranganathan, from the National Institute of Advanced Studies and the Indian Institute of Science, respectively. I think these institutions acted as the publishers, also. The title of this work is "India's Legendary Wootz Steel: An Advanced Material of the Ancient World". It was commissioned by the company Tata Steel, and came out in 2004. The rest of the book can also be found in the same page (which is Prof. Ranganathan's, by the way, would anyone be concerned about Intellectual Property issues). The first pages are HERE, and the figures are HERE.

Good discussion, Gentlemen

23rd November 2006, 11:00 PM	#2
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	#5
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.

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23rd November 2006, 07:50 PM	#1
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	#3
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	#4
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, 11:35 AM	#6
Marc Member Join Date: Dec 2004 Location: Madrid / Barcelona Posts: 256	Just as a pointer... Chris, the text in PDF you linked is not an article from Verhoeven and Pendray, but an extract (only the main text, without the figures, nor the frontpage, foreword and acknowledgements) of a book written by a couple of Bangalore (India) researchers, Dr. Sharada Srinivasan and Prof. Srinivasa Ranganathan, from the National Institute of Advanced Studies and the Indian Institute of Science, respectively. I think these institutions acted as the publishers, also. The title of this work is *"India's Legendary Wootz Steel: An Advanced Material of the Ancient World". It was commissioned by the company Tata Steel, and came out in 2004. The rest of the book can also be found in the same page (which is Prof. Ranganathan's, by the way, would anyone be concerned about Intellectual Property issues). The first pages are HERE, and the figures are HERE*. Good discussion, Gentlemen