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Old 03-30-2001, 01:14 AM
moldy Jim
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Wootz thread rescued (part)


Here's what I've got saved in the most recent file. Another one will follow that may or may not contain some of this material.

Wayne Goddard

1/9/01
***Here's What Achim Wrote***
Wootz - First attempt!

Adventures are more fun if you don't have to pass them alone.

Before i start a description of what we did i have to give credit to a friend of mine. Without Matthias, who by the way is a professional casting engineer, none of the results we received would have been possible and i would have had to work for a much longer time with a much more limited equipment to get any results at all. Now medias in res:

Last saturday we did our first real attempt on making wootz and the results look very promising. We used modern equipment, which gave us the possibility to do it all the work under controlled circumstances, but not neo-tribal at all. We first wanted to have an idea of what we have to mix into the alloy and how we have to heat it to get the desired results. Equipment downgrading will be on our list after these tests.

For our first melt we used:

1 kilogram of cast iron with 4.2 % C
1.3 kilogram of Armco-Iron without any C at all
1 gram of FeV (75 % iron, 25 % vanadium)
1 gram of FeMo (50 % iron, 50 % molybdede)
1.5 gram of FeP (70 % iron, 30 % phosphorous)

giving us a steel with 2260 g Fe, 42 g C, 0.25 g V, 0.5 g Mo, 0.45 g P

and with the following alloy

1.83 % C, 0.019 % V, 0.038 % Mo, 0.034 % P.

Heating was done in a carbon-adobe crucible in an induction oven. We first melted the cast iron, added the ARMCO-iron, added the alloy elements and covered the molten metal with melting salt, which in fact is a kind of ground up glass or sand. We had a holding time of the molten metal of about 20 minutes and cooled it down from liquid to solid temperature in about 60 minutes. From that point to down to 800? C we had another 60 minutes. After that the oven was switched off and the block was cooled down slowly in the crucible.
After hammering off the crucible, we had a nice shiney block of steel with just one small gas bubble and one small crack. The inside of the gas bubble showed big dendrites. We cut pieces from the block side and the bottom, sanded them and etched in ferric chloride and in hot alaun. The design we got is very fine, showing a net of very small dendrites. We think that we either overdid the vanadium and the molybdenum, so we had too many starting points or the cooling time from liquidus to solidus was too fast. Next time we'll change the alloy content first to see what happens.
We didn't have the time and possibility to try to forge this stuff yet, but will do so soon. Anyway, this was a very promising saturday and the results are very, very beautiful. I think they can be called wootz, but, as mentioned above, the design is very fine. I'll try to figure out a way to take a picture of the etched surface to show it here, but it may take some time.

For the neo-tribal metalsmiths the problem will be the construction of an oven which can produce the necessary heat over a long time. Personally, i decided to go on in steps. First i want to build and test burn a gas oven with a wood ash/adobe isolation and propane/oxygen gas to do the melting. After knowing if the isolation works, i'll try something with charcoal. Time window for me is one to two years. In the meantime we'll perfect the alloys and the time cycles.

Newsflash: We discussed the results of our first attempt via phone and my friend did another melt with about 1.5 % C and much less vanadium and molybdene and without the phosphor. I did get a piece of the ingot one hour ago and it looks even more promising. The dendrites on the etched surface are very big and the overall design seems to look like real wootz. Unfortunately i won't have any possibility to forge this steel in the next four weeks. So more results will come in february.
<<<>>>

Wootz

Hey, hey, guys, hold it!
Let's figure this out and if we really have found out how to make it i am sure there will be a possibility to either send some pieces out. Or, which i personally would find a lot better, show you how to do it yourself.
We talked about the alloy some days back and thought about finding some commercially made steel we can mix in to get the right amount of vanadium and molybdenum, because these pre-made FeV and FeMo alloying stuff is not available to everybody. So we are looking for some steel with only C, V and/or Mo, but no chrome or other alloy elements in the mix. I found three in the german Stahlschl?ssel:
Werkstoffnummer 1.2381 C 0.75 %, Mo 0.55 %, V 0.2 %
Werkstoffnummer 1.2833 C 1.00 %, Mo 0.00 %, V 0.12 %
Werkstoffnummer 1.2838 C 1.45 %, Mo 0.00 %, V 3.25 %
<<<>>>

Wootz-forging

Another afternoon and evening in the forge, working hard for some 4 hours and still no knife blade. But a nice piece of wootz steel.
I took a piece of one of our wootz cookies (1.5 % C, 0,003 % V) of about 2 pounds and started hammering it. Didn't use a hand hammer, but the 70 pound Ritter air hammer in a friend's forge.
It forges like D2 or 440C, very, very hard and not much deformation.
At the beginning the block showed a nice design of big dendrites on the cut-and-etched surfaces. This was an indication that the needed segregation of the vanadium took place. The first heats took a lot of time, because the block was sooo thick, about 2" by 1.5". I heated it to about 900? C (1652? F, bright red) and forged it until it was cooled to about 700? C (1292? F, dull red). I followed this cycle for about 50 times, forging the material out to a flat bar of 2" by 1/4". There were some cracks in the block from the melting so i ended up with a useable, crack free piece of about 5" in length. After a last heat i let the bar cool in still air. I ground off the scale and etched with ferric chloride. The resulting surface design looks like a very fine, wavy damascus, completely different from the dendritic design of the wootz cookies. After doing that and seeing how this stuff behaved even under an air hammer, i know why the ancient oriental smiths had to go through so many heating cycles and why these blades were so expensive then.

As a next step i will try to forge a blade from a piece of this block. I'll try to take a picture of the surface, too.

<<>>>

Yesterday i ground and etched another bar of the wootz i made and i compared the surface designs to the reference pictures in the Sachse-book about damascus steels. There are 5 different wootz steels mentioned, from stripe design over watered, wavy design to webbed design. Ours came out about half way between wavy and webbed design. If i only could take a picture!

<<>>>

After forging the first blade blank from this stuff my big respect for the ancient oriental smiths who worked this stuff into wonderful blades even grew bigger. It is very hard to forge (at 1.6 % C that's normal) and at the low temperatures you may only use, needs lots of time to get to a good result. To compare it to say 5160 steel, i think you need about 7 to 10 times longer to get about the same results. Plus you have to realy concentrate on what you are doing. One heat too hot and the designs may be lost. But the challenge is fun, too!!!
<<<>>>

1st blade

The problem is that i first have to experiment to see if any hardening is necessary and what happens if i do so. I forged the initial block in about 50 cycles, always going from bright red to dull red (920?C to 700?C) into a flat bar. Ground and etched, this bar clearly showed an advanced stadium of carbide line build-up. I then cut the bar into pieces to get rid of the bad parts and to get smaller bars to experiment with. I forged one small bar of about 5" x 3/4" x 1/4" into a stick tang knife blade using about 20 heats with the same temperatures as above. I then heated to the same temperature once for normalizing, cooling to room temp in still air. After that i heated again to red (not bright) and soft annealed in wood ash. I didn'd forge to the finished form of the blade, because i wanted to have some material all around to get rid of carbon loss. Next i roughed out the outline of the blade. I then heated to non-magnetic and edge quenched in a mixture of fat and paraffine (70% / 30%). I oven tempered the blade for 2 hours at 200?C and for another half an hour at 260?C. I ground the blade up to 600 grain. Etching was done in a 25 %ferric chloride solution. The designs on the "soft" part of the blade were about the same as before, not as good and constant as on old wootz blades or on the blades of Pendray, but clearly visible. Remember, we're still at the beginning of the quest and this was made from the first forgeable block of steel we melted. I did get a VERY distinctive temper line on this steel. The quenched part gets pitch black. It is difficult to get a good contrast on the "hardened" part. I removed the black coat with a vinegar bath of about 10 minutes and a rub with clear water and 6000 micromesh. The carbide lines on the quenched part are there, but hard to see and somewhat smaller than on the rest of the blade. Next i will mount a grip and do some cutting tests. Be patient.
<<>>>

First about the phosphorous. We mixed in some of it in the first ingot, but left it away in the following ingots. The first steel was somewhat brittle in the forge due to the high P content and this was the reason why we didn't mix it in any longer. There is some phosphorous in any steel anyway, but the steel mills try to keep the content as low as possible.
What you definitely will need is one of the impurity elements. Vanadium and molybdenum work best.
If i were you and wanted to try it with common material, i would try to get some sorel metal. This is a kind of cast iron with 3,8 to 4,7 % carbon content which is made from a high quality ore from Canada. The small amount of vanadium you need is allready in the mix and it is a quiet common material in foundrys. Mix it with some pure iron, which you can get for example from armco, to get to at least 1.5 % C and you are ready to go. Grinding it to chips is not necessary. We're going to melt it anyway. Don't forget to put some green leaves and glass chips into the crucible. The leaves will give hydrogen to the process to accelerate carbon migration. The glass will melt and cover the liquid steel until it forms the ingot so no oxygene will disturb the process. Close the crucible and you're ready to go. Don't make the ingots thicker than about 1" because if you try to make them any higher you will have severe problems avoiding gas bubbles in it.

I found out something interesting about the etching of the finished blades yesterday. We use ferric chloride to etch our pattern welded damascus blades and so i did the same with the wootz. Put it in for 2 minutes and wasn't very pleased with the result. So i put it in for some more time. No good. Longer. No good. After 2 days of experimenting with this and other stuff like vinegar, lemon juice, onion juice and such i was telling myself that something was wrong. I had the impression i was running in the wrong direction and the harder i run the farther away was the goal. Back to the grinder, polishing my priced first wootz blade again. To the ferric chloride pot. 1, 2, 3, 4 seconds in the 25% solution, OUT, under the running water, some oil onto it and guess what i had? The best designs i ever saw. It's a matter of short etching times. You can't get a relief etch like with other common damascus steels!


<<>>

For our first attempts we used an induction melting oven from the university as a heat source, but we are now working on a gas fired as well as on a charcoal fired oven, which both should work at least as good as the induction, because both take oxygen from the athmosphere around the crucible, which the induction oven doesn't.
It's not just canadian cast iron. You have to be sure to get sorel metal, because only this way you can be sure to get the right amount ov vanadium in the mix.
Our crucibles were professional one's as sold from foundry suppliers. They are described as clay-bonded graphite crucibles. We used open crucibles, but covered the liquid steel with melting salt, which in fact is a kind of ground glass or used broken bottle glass, which worked fine for us. I am now making a series of pure clay crucibles with a cover from clay to close them during the melting process. Achim

<<<>>>

03/13/2001 (sorel metal) Standard ingots are 17lbs,

The Supplier is Anderson Ferrum Corporation
in Dundas Ontario
Telephone: (905) 637-6979
Fax: (905) 627-1826

11 Willowtree Court,
Dundas, Ontario, Canada.
L9H 6T3
<<<>>>

That's about the same size sorel ingots we initially started with. We cut them up to suitable sizes and melt about 4 pound wootz ingots by mixing it with enough pure iron to get about 1.5 to 2 % C.
I hope nobody minds that i'll put this on top of the list again, but we're still not finished with our experiments and i don't want to loose the thread yet.
We now have made our own crucibles with lids from iron free clay (white clay) which will go into tests next week. We hope to get better, more consistant results with less to no blisters by using these.
What about the plans for your first wootz party? Need any advice? Achim

<<<>>>

i would suggest to go with charcoal, not coal. Forget about using spring steel or cable. The chromium content in these steels may destroy any hope for good results. If you use steel, be sure to use something really simple. A pure carbon steel like W1 will do. Better use a mix of cast iron from Sorel and a pure iron or low carbon steel. You may add powdered charcoal and green leaves if you use a closed crucible. Normal venturi gas forges won't work, they just don't get hot enough. If you want to work with a gas forge, you need forced air (at least!) and some better isolation. Most important step is to have a very long solidification process to give the dendrites and the vanadium seggregations time to grow. Sorry, i can't give you any advice as to where you can get Sorel metal. I am living in Germany, a long way from your place. Must be possible to get it from one of the brothers in the States, though.

I would suggest not to use a clay graphite crucible, because the melted steel will suck in more carbon from the crucible and may get too high in carbon content. We used them, but they were covered from the inside with some inert stuff.
About the oven i would suggest to go with an enclosed style. We're in the construction of some charcoal fired closed oven right now and if we can get it running i'll describe how it is built.


Achim

03/20/2001

Moldy, i don't know the alloy of O6, but i know that molybdenum will work to fom the pattern, too, if the amount of the alloy element is small enough. Vanadium works best, molybdenum second and some others to a degree, too. Just mix the steel with some cast iron and pure iron to a mix with 1.5 to 2 % C and below 0.01 % Mo or V and give it a try.

Everything in the structure of wootz is created by the thermal treatment. The trick is to do both thermal treatments right. First the melt with the controlled cooling down to form big ferrite chrystals (dendrites). Next the heat cycling to dissolve the ferrite dendrites and form the carbide bands at the same time. The visible structure in D2-steel comes from being a ledeburitic steel. In these steels the carbide content is so high that the carbides form segregations during the cooling process. These carbide dendrites look sometimes very similar to the ferrite dendrites in the untreated wootz ingots, but not similar to the finished wootz pattern.

Achim

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  #2  
Old 03-30-2001, 02:46 AM
AchimW
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Hey, that's great! Thank you very much indeed!

Achim
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