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Will Urban

First crucible steel puck going for wootz.

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So in a different route from my typical bloom smelting I built a propane furnace to make some crucible steel. I mixed brown glass with wrought iron and cast iron from the bloom furnaces with 80crv2 for the added alloying along with some crushed charcoal. All together 900 grams of iron and steel resulted in 600 gram puck I'm pretty excited to try forging this down. Although I will be working in a coal forge with a great bellows and hand hammering. This will certainly be a project.

On a weird note I didnt get a reading at all on the psi gauge for the burner I just adjusted everything by sight and sound.

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I forgot to add that I did do the calculations on the to get the rough carbon percentage around 1.6 percent

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I wonder why you lost so much weight ? Generally, I would not lose more than a few tens of grams on crucible steels.

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I'm thinking it's because I used bloomery iron and whatever I lost was into the glass as slag

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Sounds reasonable.  Good-looking puck, too!

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Hey all,

The second run seems much more promising. I do have one question regarding forging these. How Important is thermal cycling at the beginning and is there a difference in terms of fuels for forging ie. Propane coal or charcoal for which is better. I started forging the first of them in a coal forge.

Thanks

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Hello again. 

So I tried forging out the first puck with I'd say rather poor success. I thermo cycled the puck 6 times before beginning to forge it above the acm down to cool to the touch. Then tried to keep the puck around a medium to dull orange never working that long before reheating understanding there is a narrow forging window. I am working to get a propane forge with a way to gauge temp rather than working in an 1800s living history museum with a coal forge and by eye temperature.

While I am still working in this manner does anyone have any tips on keeping this material more workable and less likely to crumble or crack.

I am wondering if the material itself is too high of carbon or if I'm not trying to forge it correctly being mostly from boom iron there is some guessing involved.

I'm including two pictures of the aftermath a large loss of material.

 

Also if anyone has any suggestions for where to look to get metals tested for chemical composition I'd be very curious to know where you source your lab tests from.

 

Thank you

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Wish I could help, man. :(  All I know to tell you is to read all the wootz posts here and in the pinned B&B forum, but I am sure you've done that already.

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Thanks Alan I have many times over as well as watched any videos with al pendray I also bought John verhoevens book and read it cover to cover all of these options help put the puzzle together but without testing these somehow I feel there is still too much guessing involved. Without knowing the carbon I don't know if I can accurately gauge anything from forging temps to colors. I think after talking to mark green this may even affect the amount of time needed to soak and to thermo cycle. 

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Have any friends who work professionally in the metalworking industry? Most all larger companies will have a metallurgical lab. Any friends who work in machining, fabrication, foundry, etc.? 

I work at a very large machine shop, and have brought a few samples from home projects to our lab, and they were more than happy to run some tests.

It's worth a shot. Wish I could help beyond that. 

 

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On 8/25/2019 at 11:14 AM, Will Urban said:

I do have one question regarding forging these. How Important is thermal cycling at the beginning 

Re-reading through John Verhoeven's "Damascus Steel Swords," I think I may have found something that can help you.

He writes about the H-W-S method of forging crucible steels (the abbreviation stands for the names of the developers of the method.) 

"In the first step [of the H-W-S method] the ingot is heated to a high temperature for a long time. This treatment will dissolve all of the cementite carbide particles and form quite large austenite grains. It is then slow cooled which causes all of the austenite grain boundaries to become filled with sheets of cementite..."

I believe that long, high temperature soak may be vital, to dissolve the carbides, which could be causing your cracking and crumbling. 

He explicitly states in the same paragraph that this method does not produce the same surface pattern or microstructure as the Damascus blades of old. Not sure if that is important to you or not, but there you go. 

Hope that helps. 

Edit: just reread your post about you buying Verhoeven's book. I assume were talking about the same book?

Edited by Will W.

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Will Urban,

Firstly... well done for jumping in and having a crack at making some crucible steel.  Unfortunately when you start to make alloys with inspecific amounts of elements in them you can have some failures before you have success.  If you have patience and get the right advice you can have a good chance of making a good product in the end.

Now for some dissecting of your process and ingredients and possible problems.... 

1) you have used brown glass which contains Iron Sulphate compounds to give the glass the colour of brown, this sulphur will go into your melt and it will make your ingot hot short. Meaning it will do exactly what you show, it will disintegrate when you forge it.  Use green glass for your flux not brown glass.

2) you don't know your carbon content in your ingot so you have no precise idea where Acm is.  Acm (the A cementite line on an Iron-Carbon Phase Diagram) changes depending on your carbon content.  So if you have no experience with forging ingots before (you need a lot of experience to forge blind as far as carbon content goes) then you will be forging either too low to get a cluster sheet formation or you will be forging too high and will lose your pattern entirely.  This isn't really an issue unless you have significant impurities in your ingot that make your ingot hot short, so forging high will cause you problems.  You are shooting in the dark, so the long and short of it is forge at low temperatures unless you know your ingots can handle it.

3) having sulphur in your ingot which definitely came from your glass but may have also have come from your bloomery iron, will mean that you may not be able to forge your ingots at anything more than a low temperature.  The ingots which were forged with the method that you are trying to use were very pure from sulphur and so they were able to be forged higher.  The ingots that had higher levels of sulphur were forged at lower temperatures and they formed more dendritic patterns.  The way that they removed sulphur from ingots in the old days was to roast the ore very well before the bloom process, to add manganese to the crucible and calcium to help remove some of the sulphur from the ingot as slag.

4) you have a very pronounced dendritic pattern on the top of your ingots which tells me that you probably used a slow solidification on those ingots.  You may have solidified them too slow, if you did they will cause you lots of problems to forge and they can fracture as you try to forge them.  The way to try and make them forgeable is to roast them for a long time.  Al used to do a 16 to 30 hour roast at 1100°C (for 1.6%C) in a can filled with iron oxide (it stops you from losing too much carbon due to oxygen contacting the ingot).  The long roasting helps to homogenise the structure in the ingot, dissolving the smaller dendrites and weakening the larger ones.  This helps to make the ingot more forgeable and to make the pattern more visible widening the spaces between the final cluster sheets.  When you are cooling your ingots just turn the furnace off and let it cool down naturally, there are few furnaces which will keep the molten liquid in that state long enough to cause problems. If you try to ramp the fuel down you will often cause yourself problems.  One caution about roasting an ingot.... You have to make sure that you are roasting the ingot above the Agr (A graphite) line on the phase diagram, which unfortunately is not shown on many diagrams.  It is about 50 deg c above Acm.  If you do a long roasting below this temperature you WILL cause your ingot to become filled with graphite and porosity which will ruin your ingot. 

You may have all or only some of these problems, I listed them so you can better identify what may have gone wrong with these ingots.  If you give me some more information I will try to fine tune my advice for you.

I think that you have sulphur in your ingots, I also think that you have too much carbon in your ingots and that you may have solidified them too slowly. It is hard to tell without some kind of analysis or physical inspection of the ingots but that is my hunch. 

Hopefully you do better next time... keep trying and you will have success.

Cheers, Tim.

 

Edited by Tim Mitchell

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One further note... The first ingot has clear porosity issues as seen from the center and it doesn't look as well fused as the second one, that will also contribute to the crumbling of the ingot.  The second one seems to be much better fused and may forge better if you give it a good roasting.  The bloomery iron will also have silica in a large amount which you can help to remove using some calcium added to your ingot melt.  Both calcium and magnesium added to a melt help to remove silica as flux if my memory serves me correctly.

 

 

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On 9/1/2019 at 10:34 AM, Will Urban said:

I thermo cycled the puck 6 times before beginning to forge it above the acm down to cool to the touch. Then tried to keep the puck around a medium to dull orange never working that long before reheating understanding there is a narrow forging window.

On reading this in the morning with fresh eyes I wanted to add something.  IF you forged from above Acm and continued to forge the ingot as it cooled to be cool to the touch you will also cause problems.  You should not forge the ingot to below the A1 temp (727°C) and if you did that using an ingot which was high in bloomery iron then you were approaching the area of causing problems from "Cold Shortness"  as bloomery iron often has Phosphorous in it which makes the iron brittle if forged too low.  I wouldn't expect problems from forging an ingot from around 900°C unless you did forge it too cold at first with phosphorous in it, but it would be a problem if you have too much sulphur and forged at that temperature.  Bloom steel can make great crucible steel IF it is clean and comes from good ore AND if you don't have too much Phosphorous in the wood you are using for charcoal.

My advice is that trying to make crucible steel from bloom iron with unknown carbon content and then adding crushed charcoal into it (which donates carbon to the ingot) is like playing Russian roulette.  You are flirting with disaster. Making good crucible steel in the old days was a highly skilled art and it took them much time and effort to work out what would work and how to make their raw materials produce good steel.... if it could.  Also it was an art-form to forge out the ingots well without wrecking them.  SO... start your time of making crucible steel with known ingredients with known carbon content and impurities and then you will have a much better chance of success.

 

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To answer your question specifically about thermocycling, the purpose of thermocycling is to soften the outside of the ingot in order to stop the ingot crumbling under the hammer as you forge if it has a little sulphur in it, so the thermocycling is done in a gas forge with a slightly oxidizing flame.  This is normally done (by Al and myself) at around 1050 to 1100 degrees C for a 1.5% -1.6% C ingot.  It does help to make the ingot easier to forge through the repeated annealing cycles, which applies to both a gas and coal. But if you do this in a coal forge you won't get the same effect of decarburizing the outside of the ingot, unless you turn the ingot frequently and make sure that it gets plenty of air during the process.

 

The traditional roasting of the ingot was for a slightly different reason though.  It was primarily to start to break down the dendritic structure allowing the ingot to be forged easily and maximizing the spacing of the cluster sheets in the final forged ingot.  The roasting allows the impurities in the Inter-Dendritic Regions (IDR) to migrate slowly and even out in the ingot.  If you do this too long you erase the pattern and have to remelt to get it back.  But it dissolves the smaller or secondary dendrites first leaving the larger ones just slightly reduced. This means that the boldness of the final pattern will be increased.  You want to have large dendrites and slow solidification times but that causes porosity in the middle of the ingot if you solidify it too slowly and the excessively large dendrites will prevent you from forging the ingot.  Long roasting of the ingot helps to correct for the dendrites being too large as it helps to dissolve them partly, it doesn't help with porosity though.  Most of the old ingots had porosity that is why they forged them so the underside of the ingot became the surface and edge of the blade and any porosity was contained within the blade itself.  The old ingots were often 5 or 6 inches in diameter and more like a discus instead of the modern ingot style. This made the ingots more likely to get porosity in the middle of the top as well..  But generally speaking you want to avoid it and not solidify the ingot too slow or it will cause you problems even if you do a long roast.

 

Long answer with a bit of extra information....

Cheers,

Tim.

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