I guess I'm a bit confused on the wootz concept. Stop me when I get too far off the true path...
Wootz consists of hypereutectiod steel with a carbon content of ~1.5%
The trace impurities (V, Cr, Nb, etc) form carbides which precipitate out during cooling.
Forging of the billet aligns the carbides into bands.
The billets are extremely prone to red-short and must be forged at lower temps than "standard" forging.
If the billets ever becomes austenized, the bands will go back into solution and any patterning will be lost. (So, should all forging should be done at sub-critical temps?)
I see blades made from "wootz" which seem to be heated/quenched as any other high carbon steel. If the above is true, wouldn't this destroy any pattern?
Most of what I see refers to the final form as "carbides in a pearlite matrix". After heat treating does this then become carbides in martensite matrix? If you're not austenizing...how can you form martensite? After drawing out and hot working, wouldn't the form already be carbide bands in perlite? I didn't think subsequent heat treating was used.


Where can I find information on the various temperatures associated with wootz (melting, austenite formation, carbide precipitation, cooling rates...etc)? Are there transformation diagrams for alloyed hypereutectiod steels? What would be the prescribed method of heat treatment for a complex mixture such as wootz? I find a lot of articles on wootz now, but they all talk in broad general terms without referencing actual temps.

I've talked with a few guys making crucible wootz. The ones willing to discuss actual techniques still seem a little mystical on the heat treat...or I'm just missing something that might/should be blatantly obvious.

I just finished a steel melting furnace and will be making some crucibles over the next couple weeks to do some test melts. I have a variety of steel scrap available (1095, 1050, 4130, W1, A2, A6, O1) as well as some powdered samples of Nb, Ta, W to experiment with. I'd really like to cut down on some of the experimental stage, though!

Don I copied this from an eirlier post. I don't know if it has what you are looking for or not but it is an intesting read. http://playground.sun.com/~nozh2002/Bulat-Achim.html The first part is in russian but there is a translated version at the bottom.

Bill

Don, though this is of little help, when I bought a bar of wootz from Dennis at Brisa in Finland, it came with an instruction saying that they recommended against heat treat. It is 'salt-and-pepper" as opposed to the prettier grain patterns.

Have you read Figiel's book, "On Damascus"? It's a non-technical book on old wootz stuff, but has some excellent information and insights.

It's a pity some of the old info at Sword Forums seems inaccessible, as there were some good discussions in there. The new Primal Fires seems like a good place, too, for additional info.

If you can initiate a dialogue with Achim from Outpost, he is probably one of the best sources. He seems to approach it very technically.

I always thought that it wasn't further heat treated after the forging/cycling. It seems some of the guys making it are showing blades with hamon/temperlines and other "quench" related features. From what I understand of the process, it seems like any austenizing/quenching would pretty much negate the whole wootz patterning that took a lot of work to create. Not being all too familiar with the process, other than what I've read, I was curious as to how others have handled wootz. Many persons making it refuse to answer questions about the process...even basic principle type questions. I forgot about Achim, he's been really helpful in the past with pointers. Of course, experimentation is half the fun :D . I'm ready to start some melts now and justn trying to clear up some of the conflicting info I run across.


Bill,
Perfect! Although, now the questions above on austenizing vs pattern loss have me wondering!

Not much help but I have a video tape at home of Al Pendray forging out a wootz billet and it definitley appears he is forging above critical temp. Just how much above is at question and I believe the key is that since it is a hyper-eutectoid steel it would take elevated temps to actually put all the excess carbon in solution and thereby eradicate the patterning. I was under the impression that it couldn't be worked above critical either. I actually don't see how you could forge and shape any steel to any extent at temperatures below critical. Just my take and observation, I know next to nothing about wootz but it was my understanding as well that it wasn't further heat treated after forging and shaping.

Well after looking at that paper, which I believe was written by Achim, I'm a bit more confused:

"After this diffusion heat, the heat cycles and the forging starts. The ingot is heated to 850°-920° Celsius and is cooled to about 700° Celsius and then heated again. This heat cycling is done for at least 100 times. During those heat cycles, the ingot is forged into a flat bar. I recommend to start the forging only after about 20 heat cycles to get rid of the initial cast structure of the ingot.

After forging it to a bar and finishing the heat cycling, the bar can be forged into the shape of a blade or any other forgeable object by keeping the maximum heating temperature ALWAYS within the range mentioned above. ALWAYS stay below austenitic temperature!"

This states to both forge and cycle the steel in the 850-920 degrees Celsius range (1562-1688 degrees F) AND stay below austenitic temperatures??? :confused: Am I missing something? To my knowledge all steel begins to go austenitic at around 1320 degrees F.

Tai has also forged several Wootz blades so I'd re ask in the Outpost as both Tai and Achim pretty much visit there.