Wootz Makers and Production Methods

[Tim Mitchell]

Hi Krysztof,

 

Thank you for sharing your method and for the links to your ingot forgings. They look really nice. I wonder if you are having problems with forging your ingots because of graphite formation in the ingot and a very strong dendritic structure? Because you let your ingots cool for so long they are getting a very strong dendritic structure which can make them more fragile in forging.

 

Also on one of the close up pictures I saw what looked like graphite porosity (from slow cooling) in the steel which will make the steel weaker and harder to forge at low temperature. What temperature do you try to forge your ingots out at? If it is too low or if you forge too quickly that may be your problem.

 

Remember that when you are doing the anneal cycle on your ingot you need to do it in an atmosphere which has oxygen in it (slightly oxidizing flame) that way it creates a de-carburised layer on the outside of the ingot. If you don't do this your ingots may crack as soon as you start to forge them.

 

Kind Regards,

Tim.

[Tim Mitchell]

Hi Jokke, yes I have heard that some people use a water bath to keep the pressure up in the bottles, that is why I have manifolded them. Our weather over here is a bit warmer than yours too . I have also had icing due to moisture in the gas (poor quality gas) in the US. My regulator would require a good wack to get the diaphragm unstuck.

 

Regards,

Tim.

[Krzysztof Rusek]

Hi Tim,

Yes ignots are hard to forge, near 5 cycles are requred to start initial deformation. Addition of Cr and V makes them even harder to forge cakes. Graphitizatoin occurs because of graphite crucibles, i just anneal and decarb that part to make it easier to forge.

I think for complete forging down cake to bar it takes around 50-60 forging cycles for cake with Cr and V and around 40 - 50 cycles for cake made of nails and charcoal (by hand). Now im forging first time whole cake (previously i forged halfs to see if there are porous regions inside cake or other problems) and it is really slow. I forge in orange temperature ( I try to maintain around 900 C). One cake cracked because of inproper forging (i tried to rift a hole throught cake and then roll it to bar but failed - steel started to crack)

 

Cake fresh out of crucible. Steel is with around 0.5% Cr, minimal addition of V and has around 1,5 - 1,7%C

 

Initial forging of cakes. Around 10-15 cycles.

 

Other side of initial forging.

 

Actual state of cake. Nearly 40 forging cycles

 

Other side of Forging. This will be main plane of bar/knives.

[Tim Mitchell]

Hi Krysztof,

 

Thanks for explaining, I can imagine that the chromium would make it harder to forge. I personally would forge it out at 950°C to 1050°C, which you would find makes it easier to forge. They look like they forged ok.

 

Normally you have to get the ingot flat enough (12mm thick) to be able to punch and drift the ingot into a ring (Niko's Method) He forges them at around 1100°C when doing that. If you get the ingot down to that thickness it is much less prone to crack when you drift it, as you have broken up most of the carbide structure.

 

The graphite doesn't come from the Clay Graphite crucibles, that will add some extra carbon, but that doesn't cause any formation of graphite. The graphite comes from leaving the ingot for too long between the A1 and Agr temperatures on the iron carbon phase diagram; between 723°C and around 1050°C (for 1.5% carbon). As the ingot stays in this region too long you get graphite formation in the ingot. To remove this graphite you need to go above Agr temperature ie. around 1100°C and forge the wootz bar very well to close the voids where the graphite was. Some smiths in the Punjab were described as forging at a white heat (probably a mid to bright yellow). These ingots were slow cooled with a porous area in the center and would have had some graphite formation... which is probably why they forged them so hot. (Abbott's 1850s account)

 

If you decarb the ingot enough and forge it gently at first you will be able to forge it at this temperature. Just watch out, if you go too high in temperature you will lose the pattern..... a little higher still and it will crumble......I would stay around the 950 - 1050°C range to be safe.

 

Regards,
Tim.

[Jokke]

well,

I would forge mine under 900, at around 850 down to 780°C, less cracking, but more cycles needed.

 

Krysztof, you could try the Donut-technique, when you have hammered your puck down to be round like the above...

 

here another link:

http://www.tf.uni-kiel.de/matwis/amat/iss/kap_b/illustr/ib_5_3.html

 

mainly the "usual subjects"

 

Greetzes

Jokke

[Krzysztof Rusek]

Tim

Thank you for information, i will try to forge in a little higher temperature, will see what i will have in bar. I think Punjab cakes were even bigger then mine - around 2,5kg to over 3,5 kg and thats a lot. When i cutted cakes (around 10 of them) i inspected them looking for porous regions. Sometimes they happend, but in my cakes there were at most 10% of cake. Outside of cake is porous and has holes but after annealing it is easy to forge and dont cracks. Problem is "hard core" of cake, moving that steel is really for patient man.

 

Jokke

I tried that style, but im too inexperienced smith to do it properly. Next thing i lack proper equpment to forge that way (anvil horns of different diameter). First i need to learn how to forge bar in easiest way, then i will learn this "Donut-technique" then "serpent technique". On that failed cake i will learn firewielding of that steel (it is possible, one of more experienced smiths showed me that)

Few pictures of my cracked cake

 

Forging ok, started to drifting a hole.

 

Hole drifted, there were some cracks and i didnt saw them. Start of problems

 

Cracked cake.

 

other side of cracked cake.

 

[Tim Mitchell]

In modern times most wootz makers have forged out their ingots at your temps Jokke, and I have done that too (for final shaping of blades), but that creates dendritic type patterns and not cluster sheets of carbides. This is (as Niko showed) because the carbon has to get hot enough to be able to become soluble and to become free in the steel. Otherwise we are just expanding the dendritic structure and stretching it out to make stripes which are broken up. Many of the old blades had strong sheets of carbides which only form when the carbon is hot enough to move in the steel. There are more makers these days who are forging at around 1050°C or higher with plenty of success and getting some really nice patterns with good cluster sheets. It isn't the only way of course, but it does have some advantages in my experience. Many of my customers liked the dendritic patterns so I would forge at the lower temperature as you do Jokke, it can make some lovely looking blades, I just had to go slow.

 

The last ingot that I forged, I forged out at 1100°C (where Niko forges) and after cycling 6-8 times in an oxidizing flame I forged it straight out... gently at first and then once it started to move well, I used a striker and then moved onto a power hammer. The whole thing was forged to a bar and drawn out in just over an hour. I didn't get one crack. The carbon content was 1.5%. (more carbon you have to go slower) It is also low in sulphur and phosphorous which helps forging but Niko forges at this temp with increased phosphorous with no problems.. just gentle forging.

 

For me the key is to get a good decarbed layer on the outside and to not work the ingot too cool. In my experience, if it gets too cold you risk cracks, and if you work it too fast you will crack it. This is what it seems you did with your donut attempt. I think it should have been drifted much more and much slower before you opened it up. The chromium may have caused some problems, I can't say for sure. Make a large diameter drift and start drifting it from a smaller hole... gently and don't let it get too cool. I work in a 50°C forging range, pull it out... bash it a few times and when that colour gets to a bright orange it goes back in the forge. It stays out for no more than 20 seconds, usually less.

 

Let us know how you go and GO SLOW!!! Impatience is the mother of failed ingots! Going slow is even more important seeing you have slow cooled ingots, you can go faster with ingots which were cooled quicker.

 

Regards,

Tim.

[Jan Ysselstein]

Jokke,

 

Thank you for adding the facebook link, it has been interesting to look at. I will start using it when someone familiar with facebook walks me through the needed cautions. Two images were posted that I will be using as "standards" or goals .. both are within reach ( almost there). I will also add an image not found on facebook but related. The top photo as a different pattern from the bottom two photos ( the bottom two are related though slightly different).

Here are the pictures from facebook and some pictures of (repeatable ?) trials I did on another thread. I will have to edit my pics in later, as I do not want to lose this post. My pictures are as forged, prior the heat treatment.

Jan

 

 

 

 

 

 

 

as forged

 

 

 

 

 

Edited December 20, 2017 by Jan Ysselstein
privacy

[Jur de Stoute]

Gents,

 

A short introduction. My name is Jurjen and I live in The Netherlands. I have been bloomery smelting and forging for many years already. With an interest in making knives of servicable quality. that are actually being used. The feedback I get from people using my knives is how surpirized they are with the quality of the edge of homemade bloomery steel. Even compared to modern steel. Usually they say the edge holds better than modern steel altough the do rust alot more.

 

I never used the wootz or bulat method, since I have the feeling this is to distant to european smelting practises. So my preferred method of making steel is the evenstadt method. perhaps followed my carburizing in carbon rich materials. The big advantage of remelting homemade iron is that you are able to remove the small "bubbles" of slag that are inherent to bloomery iron no matter how good the quality. If you use bloomery iron/steel or carburized bloomery iron I found that you get a microscopic "saw" edge instead of a nice smooth edge you get when resmelting the iron to steel.

 

But I am responding because of the discussion on forging wootz cakes en all the chemical structures (which I am not so familiar with). But what I did notice when remelting iron to steel is that I pull out the small steel blooms of remelted steel and start hammering them when still yellow. So when they did not have time to cool but straight after remelting. That way even the high carbon is very soft and easy to forge.

On the contrary ,If you let the small steely remelted blooms cool first, they are almost impossible to flatten after reheating. Like hitting a hard rock even with the sledge. I never figuered why, but may have something to do with those dendrites and all you are discussing here. So basically my question is has somebody done the same thing with wootz cackes: start forging the buttons when they have cooled enough to solidify but have not cooled completely?

 

 

Just curious. Also no idea what the effect on the patterns are since that is usually of minor importance to me.

 

Jur

[Tim Mitchell]

Hi Jur,

Thanks for your post and for your thoughts. I know of no one who has done this, I don't see why someone couldn't do it, but most smiths who work wootz let them cool and then decarburise the steel outer layer before forging. Traditionally the cakes were made in a separate location to the place that the cakes were forged out and so few if any would have been worked straight out of the furnace.

 

It is an interesting exercise to try and it may make a difference, who can tell?

 

Regards,
Tim.

[Jan Ysselstein]

Jur,

Thanks for the details on the bloomery iron ( an optimistic note ).

I am only speaking for myself and have no idea what others are thinking. Each ingot must have some information I need to know ( frankly, sometimes I wonder what that might be as obviously I have not found it yet), so I examine all of them under the microscope and record them. I hope to eventually be able to associate the process with an ingot appearance and the final steel look. So that test,forging a cooling cake is not valuable enough at this stage of the learning process. Because making real wootz is so painful to do, this is a very slow learning curve and I will not be able to take advantage of your suggestion for a long time.

Jan

[Jokke]

found some new pics on wootz-ovens on fb:

https://www.facebook.com/media/set/?set=a.468368493323938.1073741835.438515189642602&type=1

 

seems to work

[Jan Ysselstein]

Thanks Jokke,

 

This person has an interesting set of experiments going, quite clever. The knives are very beautiful but his labels give no indication the steel is his or factory made..do you know what it is. The little silver ferrule on the Ebony knife is a nice touch.

 

Jan

[Krzysztof Rusek]

Hello everyone.

Finally i can post some pics of mine steel. Any tips on proper eching wootz type steel? I eched in FeCl, i was reading about eching in FeSO4 (ferric vitriol in Anonsov) or is nitric accid the best? I got problem in proper eching to leave nice resistant coat. Are you covering eched blade by some paint or something else to make it more resistant against rubbing off?

 

I will be thankfull obout any tips/tricks.

 

Sincerly

Krzysztof Rusek

 

[Jan Ysselstein]

Krzysztof,

 

Thank you for posting your beautiful steel here... one can etch with (Fe)2(SO4)3 = Ferric Sulfate, or Ferric Chloride= FeCl3 or Nitric Acid and there are more. Most of the contrast comes from he Cementite and the surrounding material..if that is pearlite or tempered martensite..the surrounding area can get quite dark with most acids.

Some blades seem to be at their peak when polished and only touched with a bit of acid , some structures allow very deep etching to reveal a strong pattern, The deeply etched patterns seem less sensitive to losing their appearance during use ( or handling).

I do not worry about that...the pattern is there and if the user wants to see it clearly in the future, you can bring it back or the person can bring it back a little by following your toned down instructions.

Jan

Edited September 5, 2015 by Jan Ysselstein

[Tim Mitchell]

Thanks Krzysztof for sharing your pictures of the steel. Can you share about what temperatures you used and what carbon content you were aiming for? You have some dendrites visible in the final pattern, so it looks like you were forging below the Acm temperature level for most of your forging process. It also looks like you gave it a good roast or soak time before forging, is that correct?

 

About the etching, if you want a more durable etch, you can always do the reverse etch that I often do... it isn't traditional, but I heat the blade before the quench in an oxidizing flame which pulls carbides from the blade surface and decarbs the surface layer just a bit. When etched these microscopic pits become larger under the action of the ferric chloride. This makes the surface steel the shiny part and where the carbides were becomes dark. It is a much more durable layer though and significantly more rust resistant, although it does mask some of the natural beauty of the wootz.

 

Kind Regards,
Tim.

[Andrei Petrocenco]

Hi Everyone,

 

My name is Andrei and I do artisitic metal work such as restoration, blacksmithing, bronze and brass casting and I have over 25 years of experience in this area.

 

The reason why I'm writing in this post is begause I'm interested in undertaking wootz smelting. I was wondering if anyone could point me out to anyone who can provide wootz making introductory classes. I live in Ireland and I was looking for someone in the European region, as traveling to the US to take classes from Ric Furrer would be quite costly and time consuming.

 

I appreciate any help and suggestions.

 

Regards,

 

Andrei.

 

www.bronze-iron.com

[Mark Green]

Andrei,

There is a lot of info on line, and here. You could likely figure it out yourself.
While a class may help, doing it yourself will still take some learning.

 

Making crucible steels, especially wootz, can take a lifetime of experimenting. And then, learning to forge it, is another whole learning curve.

The equipment you need is not too expensive, depending on how you want to make your crucible steel.
You seem to have some basic experience, just look at what is around for free first.

Best of luck !!!

Mark

[Tim Mitchell]

Hi Andrei,

 

Considering your experience you will have no trouble stepping into making crucible steel. I agree with Mark, there is plenty of information out there and in this thread to help you get started. There really isn't much to getting a usable ingot that can be forged out, it only gets hard when you try to make your own crucibles or move away from the standard ingredients and methods that are in this thread.

 

 

Using standard ingredients (meaning with known analysis) you should be able to get a usable ingot the first or second time. This is so long as you:

 

- Use Clay Graphite crucibles or Silicon Carbide

 

- Keep your furnace atmosphere slightly reducing not oxidizing.

(an oxidizing atmosphere can cause bubbles around your ingot base and higher nitrogen content in the steel and therefore a more brittle ingot)

 

- Don't get the melt too hot or you will get porous areas or bubbles inside the ingot

 

- Make sure the ingredients are fully melted (dip method works well in conjunction with an optical pyrometer for repeat-ability)

 

- Keep your calculated carbon level between 1% - 1.5% (beginners have a hard time with high carbon ingots)

 

- Add a bit of Manganese to the melt (helps with forging and with pattern - almost all old Persian recipes added some manganese)

 

- Don't try to do a realllllyyyy slow solidification (too slow causes a fragile ingot especially for a beginner - 1 hour is fine to handling temp)

 

- Do a good roast of the ingot for between 1 and 3 hours before you forge the ingot

(to normalize and decarburize the ingot outer layer, should be done in a neutral or slightly oxidizing atmosphere but not for too long if oxidizing or you will pull too much carbon out of the ingot)

 

 

 

Once you have a good ingot:

 

- Forge slow at first and not too cold

 

- For the beginner keep the temperature around 950°C for 1.5% Carbon or 800°C for 1% Carbon while forging

(this is a safe temp for a standard dendritic pattern in crucible steel with little risk of getting it too hot. Any porosity won't close at this temp, the steel will end up slightly more brittle than forging at higher temps and you won't get the woodgrain or watered patterns that come from the carbon moving more freely in the steel)

 

 

These points should help you to avoid the common pitfalls that trip up beginners and to be able to get success not long after you begin. Perfecting the making of crucible steel can take a lifetime and is lots of fun, but you can get some workable steel without too much trouble and with a bit of advice. It is much easier these days than when I started out 15 years ago, there is a lot more information out there now and some really good guys who will give you advice when you get stuck.

 

All the best with your journey,

Tim.

[Andrei Petrocenco]

Tim and Mark,

 

Thank you very much for your help, folks. Really appreciate it.

 

Andrei.