Viking Swords and Wootz

[Jeff D]

Hi Chris,

Thanks for your reply. You are correct they are taking about crucible steel not wootz. There has been a trend in using the terms interchangeably although they are different. I interpreted your question wrong. Now that I think I know what you are asking. I suspect it is the lack of hammering of the fakes that would be the problem, hammering that would not be required on crucible steel. I know you know this much better than me. Do you mind me asking, doesn't it takes multiple foldings to form the stringers, not just hammering to shape?

All the Best
Jeff

[Chris Evans]

Hi Jeff,

Originally Posted by Jeff D

Hi Chris

Do you mind me asking, doesn't it takes multiple foldings to form the stringers, not just hammering to shape?

All the Best
Jeff

Sponge iron has to be hammered extensively every which way to reduce its slag contents (by squeezing it out) - This is done as a matter of course. And the extent of hammering it receives ensures to a considerable degree its quality, though not entirely.

Without knowing the answer to your question, it is my view that some folding would have been unavoidable. But whether the ancient Viking swordsmiths went as far as others, say the Japanese, in the pursuance of refinement by way of repeated folding, I cannot say. I think that a much hammer refined blade would have represented a superior product, and this simply on the basis of labour input. Just how aware the Viking swordsmiths were of the need for extensive hammer refinement of sponge iron, I am ignorant of and here we need a knowledgeable archeological metallurgist, something that I am not.

However, I'll venture to question the presumed superiority (in the article) of a Wootz blade against one well made from sponge iron and hardened. If the ancients could quench and temper Wootz, then they indeed would have had a superior blade, but that would have required being able to heat just sufficiently to austenitize the pearlite without dissolving the carbides and then quenching, a task requiring very good temperature control, not to mention knowledge. On the other hand, steel made from sponge iron can be quenched and tempered with relative ease - This is how swords, indeed all steel implements, were made before the advent of molten steel making, and we do know that perfectly serviceable and many excellent blades were produced this way.

In a past thread we have discussed whether Wootz was quenched and tempered in the old days, and there is some evidence that some of it was. As to how they went about this and how successful it was I am not sure - Without having done any first hand experiments, or reading of any such attempts, my guess is that if high carbon Wootz is heated to the extent that a substantial amount of the carbides are dissolved, then upon quenching and tempering its microtructure would turn into a proverbial dog's breakfast with very uncertain mechanical properties.

Cheers
Chris

[Jeff D]

Hi Chris,

Thank you for your answer. Regarding the quenching of wootz, what do you make of this. Sorry this is the best picture I could make.

Thanks again
Jeff

[Chris Evans]

Originally Posted by Jeff D

Hi Chris,

Thank you for your answer. Regarding the quenching of wootz, what do you make of this. Sorry this is the best picture I could make.

Thanks again
Jeff

Hi Jeff,

Interesting photo. Edge appears to be heat treated - Am I right?

If so, this could have been a means of countering the negative effects of dissolution of carbides, as the unhardened spine would have retained sufficient strength to render the blade serviceable. I wonder how they would have quenched the edge only of a deeply curved blade ...What would be really informative is to take a cross section of the blade and examine its microstructure......

This is pure speculation on my part, but another way of hardening Wootz would have been to decarburize the steel by prolongued heating in an oxidizing atmosphere to reduce its carbon content and then, after a process of homgenization by hammering and folding, quenching and tempering - The obvious difficulty would have been knowing when to stop the decarburization process.

Cheers
Chris

[Jeff Pringle]

Whoa, you guys type faster than I do!
This repeats some of what Chris just stated, with a different spin...now I got to go think about heat treating...
Wrought iron and steel are very different animals, I do not think it is advisable to extrapolate from one to the other. What might be a welcome crack arrestor in iron could be an unwelcome stress riser in steel.
The slag stringers are a natural outcome of the method used to refine freshly smelted bloomery/tatara iron and steel, repeated folding, which has the primary purpose of removing the slag and homogenizing the metal. The more folding done, the less slag there is and the grain of the slag inclusions becomes finer. The edge of a sword would be severely compromised by a large slag stringer crossing there, or in the metal just behind the edge, so the metal used there is more refined. In the body of the sword, supported by more surrounding mass and not at the stressful cutting edge of the blade, such a degree of refinement is not needed so they used material that had less labor and materials invested in it. The slag stringers are in the middle because it is a more efficient way to make a blade and they can do no harm there, no other argument is required. This Moro spear nicely illustrates the technique.
The wootz/crucible steel method trades in the ‘repeated folding’ refinement for a liquid separation, but the goal is the same - homogenous metal and little or no slag.
It is entirely possible that the Ulfberht Co. got a nice price on imported ‘pre-refined’ steel for a couple years and when the economic situation shifted they continued on with the usual stuff, but I have yet to read the Williams article and see what it actually says. The Guardian article is goofy, but a good conversation starter!
Here’s another +Ulfberht+ (as opposed to +Ulfberh+t) analysis -
http://fornvannen.se/pdf/1980talet/1981_024.pdf
Metallografisk analys av inläggningar i vikingatida svärdsklinga,
inv. nr SHM 907 Go, Hogrän sn, Ålands
Av Mille Törnblom

[Chris Evans]

Hi Jeff (Pringle),

Thanks for your very informative post, to which I can add nothing of significance. Any chance of a rough translation of that most interesting article, just to get the gist of it? And as someone who has had a fair bit to do with Wootz, could you shed some light on its historical heat treatment as uncovered by modern research, is such information exists?

Cheers
Chris

[ward]

Happy new year

Little different direction in this article
http://www.physorg.com/news150373962.html

[Gonzalo G]

Originally Posted by Chris Evans

Sponge iron has to be hammered extensively every which way to reduce its slag contents (by squeezing it out)

However, I'll venture to question the presumed superiority (in the article) of a Wootz blade against one well made from sponge iron and hardened.

In a past thread we have discussed whether Wootz was quenched and tempered in the old days, and there is some evidence that some of it was. As to how they went about this and how successful it was I am not sure - Without having done any first hand experiments, or reading of any such attempts, my guess is that if high carbon Wootz is heated to the extent that a substantial amount of the carbides are dissolved, then upon quenching and tempering its microtructure would turn into a proverbial dog's breakfast with very uncertain mechanical properties.

Cheers
Chris

Chris, I am confused by your words. I understand that old steels were made with bloomery iron, and not sponge iron. Or instead, decarburizing cast iron with high carbon content, which is more easily molten at lower temperatures. Sponge iron, as I understand it, is another kind of product. I feel much of the discussion about wootz is biased by speculations which tend to maximize, or instead, minimize, the value of this type of steel, making statements above of the facts. It is scientifically healthy to have some dose of scepticism in front of myths and distortions. But the fact is that we don´t have enough samples of wootz blades, studied and tested, and even less scientific comparisons among wootz blades and european blades from the same period. On the other side, it seems that there is another manuscript from Al Kindi dedicated to the thermal treatments of the blades made with wootz, which is not yet printed, though I understand maybe there is already an italian traslation. There are references to this work on the book Medieval Islamic Swords and Swordmaking, by Hoyland & Gilmour.

But even with the publication of the translated manuscript, I belive we will yet have many questions for years to come about this subject. I hope the archaeometallurgy helps us in the progresive clarification of many of our questions. Other discoveries look ahead on the study of the traditional swords of the world, as the viking swords seem to demonstrate. I still believe the articles about viking swords refer to a relatively clean high carbon crucible steel, and not to wootz. The swedish article mentions the presence of 0,8% refined carbon steel in one of the edges of the studied sword, and 0,4 to 0,6% carbon steel on the other edge. This opens the possibility of speculate about some specialization among the different edges of the viking swords, or at least in some of them, but it is only a good? pretext to continue our conversation. Some of the viking swords seem to be very complex in their structure, not because they are multilaminated in the japanese way, but because they have many different types of steels and irons in their composition, all welded in the make of the blade.

This kind of solution is not less sofisticated, or work intensive, than the japanese nihonto, in my opinion, but this is said with no regard of the differences on their success to have the best relation metallurgy-geometry-design, or to do with more effciency the expected job, as it is another very difficult subject to discuss with some scientific basis. Of course, this are only some of my ideas, and I can be wrong.
Regards

Gonzalo

[Chris Evans]

Hi Gonzalo,

Originally Posted by Gonzalo G

Chris, I am confused by your words. I understand that old steels were made with bloomery iron, and not sponge iron.

The stuff that comes out a bloomery is sponge iron, a miture of iron and slag. See http://en.wikipedia.org/wiki/Bloomery.

Or instead, decarburizing cast iron with high carbon content, which is more easily molten at lower temperatures.

That is another way of making steel, but it's a later development. See
http://en.wikipedia.org/wiki/Steel#Ancient_steel

I feel much of the discussion about wootz is biased by speculations which tend to maximize, or instead, minimize, the value of this type of steel, making statements above of the facts. It is scientifically healthy to have some dose of scepticism in front of myths and distortions. But the fact is that we don´t have enough samples of wootz blades, studied and tested, and even less scientific comparisons among wootz blades and european blades from the same period.

I totally agree.

On the other side, it seems that there is another manuscript from Al Kindi dedicated to the thermal treatments of the blades made with wootz, which is not yet printed, though I understand maybe there is already an italian traslation.

I look forward to reading it.

I still believe the articles about viking swords refer to a relatively clean high carbon crucible steel, and not to wootz.

Allowing for some ambiguity, Wootz is crucible steel. See http://en.wikipedia.org/wiki/Crucible_steel

The swedish article mentions the presence of 0,8% refined carbon steel in one of the edges of the studied sword, and 0,4 to 0,6% carbon steel on the other edge. This opens the possibility of speculate about some specialization among the different edges of the viking swords, or at least in some of them, but it is only a good? pretext to continue our conversation.

Around 0.8% would have been optimal, but controlling carbon content is not easy - We must not forget that the ancient swordsmiths did not even know that steel was iron+carbon. Chance played a large part in the manufacture of ancient steel and this is why really good blades attained legendary status, in other words they were rare.

Some of the viking swords seem to be very complex in their structure, not because they are multilaminated in the japanese way, but because they have many different types of steels and irons in their composition, all welded in the make of the blade.

This kind of solution is not less sofisticated, or work intensive, than the japanese nihonto, in my opinion, but this is said with no regard of the differences on their success to have the best relation metallurgy-geometry-design, or to do with more effciency the expected job, as it is another very difficult subject to discuss with some scientific basis. Of course, this are only some of my ideas, and I can be wrong.

Well, my take on this is that a sword, indeed any weapon has to be only good enough to get the job done. Any more does not win wars.

Cheers
Chris