Jump to content
Will Urban

First crucible steel puck going for wootz.

Recommended Posts

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.

20190822_204142.jpg

20190822_204128.jpg

20190822_135500.jpg

  • Like 1

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

Sounds reasonable.  Good-looking puck, too!

Share this post


Link to post
Share on other sites

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

20190824_085916.jpg

  • Like 1

Share this post


Link to post
Share on other sites

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

20190831_201906.jpg

20190831_201856.jpg

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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. 

Share this post


Link to post
Share on other sites

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. 

 

Share this post


Link to post
Share on other sites
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.

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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.

 

 

Share this post


Link to post
Share on other sites
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.

 

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

Let me try to reply to all this awesome information piece by piece.

Will w

I went back and read that section over yes same book. I absolutely would have to agree with the necessity of soaking which is mistake 1 on the first try. I thermo cycled where I should have done a roasting heat. On a plus side I have tons of iron oxide.

Tim 

First off thanks for taking the time to spell out numerous issues I was having with this approach. I am planning on setting up a 5 crucible test with parts from one bloom. one as a control and the other 4 changing some of these processes to eliminate variables and find out what this ore is making.

1. I didnt know brown glass was iron sulphate good to learn something although not good to learn three runs in. I assume the lead oxide from the green doesn't effect the steel. I was pondering using beach sand as my flux so it will work as a flux but it will further add authenticity to the approach if my thinking is correct. Perhaps you could elaborate on that if you have any experience there?

2. When you say low heat do you mean not much above about 1000 to 1100C .

3. I would think the assumption of sulphur to be true it acts a lot like other metals I've forged with sulphur. But I am a bit leery to start alloying in more variables like manganese and calcium without knowing if it's the bloom iron or the glass or both. The bloom iron I have been using is from ore that bethlehem steel was using I believe it's from the cornwall mine so I can probably look up the ore element analysis.

4. Ironically the way I did cool it was keeping it in the furnace until color was gone then taking it out an air cooling. I will try roasting in a propane forge with a thermocouple in an iron oxide tub to see if that improves the matter. But without analyzing my way of making bloom iron with consistent ore source and the crucibles after it'll always be guesswork no? And in theory every run could be different regardless if it's from bloom iron depending where the carbon is situated in the bloom(its usually lower as that area has more time to carburize in my experience.

Thanks for the encouragement. I think you misread the area on thermocycling I thermocycled to above acm then let it cool till I could touch it. Then after those cycles I brought it up to orange hot and tried to keep it in the orange red orange the entire time. It did get close to a yellow heat a time or two.

So if I'm reading the rest of what your saying right then the first thing I should do with ingot number 2 is roast for about 16 to 30 hours then thermocycle in the propane to slightly decarburize the surface then forge at a lower temperature slower. 

Thanks for all the information this is almost too much to digest but being the 2nd time I read through that I hope I got to everything you said. I will definitely be trying to fix these things and get better success

Edited by Will Urban
Unit istake

Share this post


Link to post
Share on other sites

Will, happy to help.  The green glass is fine, it actually has some copper in it to create the colour and so that does help the melt a bit.  Al used to use the green glass and it never caused him problems and that is what I use and have never had issues.

Concerning heats... High heat is above Acm.... if you know what that is.  Low heat is at least 100°C below Acm.  So for 1.6% C ingot high heat is 1050 - 1100°C and low heat would be around 800°C.  The issue is that if you have lower carbon (1%C) then your Acm point is 820°C  and so forging at a mid orange heat is too high... However I think your issue is too much carbon not too little.

The problem is that if you are trying to forge above Acm with an unknown ingot carbon percentage, then you will cause problems for yourself.  You will have more failures than success. Some ingots in the 1.5% carbon range can only be forged at 800°C or lower or you will crack them... this is because of higher impurities that make them hot short.  Giving it a good roast in the gas forge for 1 hour should decarb the outside of the ingot enough for you to do a gentle forging.. But if you forged the ingot at a mid orange heat and had it crumble then you have very few possible explanations.  1) Your carbon content is too high.... waay too high. 2) your sulphur level is too high...  3) you didn't roast it properly.. coupled with sulphur in the ingot  4) you forged too fast and hard.  There are a few other less likely possibilities but I think what you are dealing with is one of these, or a combination of these.

Calcium is not an alloying ingredient it is a fluxing ingredient, it helps to reduce porosity in the ingot, it removes some phosphrous.  Most of the old ingots had some Manganese to help remove Sulfur and it helps with the overall quality of the steel. 

I wouldn't do the long roast until you know that you are getting consistent and good quality ingots or it will be a waste of time and fuel.  It won't make much difference to cracking the ingot or not if sulphur has been your issue.  A good 6 hour roast would be helpful though (in iron oxide) and then a decarb in the forge for around an hour. 

It only takes a small amount of Phosphorous to make your steel cold short especially at higher carbon levels.  I would add some calcium to your melt... a large spoonful of crushed shell, in order to reduce that from being a problem.  It is easy to have a highish phosphorous bloomery iron. Unless you know your blooms are low in phosphrous (from your charcoal source)  I would be adding something to reduce that and to help kill the gasses in the ingot as a matter of course.

Cheers, Tim.

 

Share this post


Link to post
Share on other sites

One other thing, the old method of using long roasting periods for ingots may have been to help remove any remaining sulfur in the steel.  They would roast the ingots in Hyderabad for a long time, pull them out, hit one with a hammer and if it broke they would put them back in and roast them again.  This was either because their carbon content was too high.... or it was because they were needing to get any remaining sulfur down to a level where their ingots were no longer hot short and could be forged. So if you do have sulfur in the ingot a good long roast will help to get some of it out of your existing ingots.... just a thought.

 

Share this post


Link to post
Share on other sites

So tim and everyone, I have a question there is a good chance that I can get some tests done by a friend who works for a steel company in pa. He said that I should tell him the elements that I would be looking for specifically so he can tell the guys what to test for he will try first to test with a certain type of xrf test. And he said if that doesn't work then it may cost some for the tests but besides for carbon and some carbide formers I know what should I also look for.

 

I decided I really need to know what I'm working with if I want to actually get good results. My hope is to test raw bloom, consolidated bar bloomery iron. And the last crucible puck where I carefully recorded everything from known wrought and cast to see if my assumed carbon and vanadium is correct

 

As always thanks in advance. You guys have already helped immensely. 

 

Will

Share this post


Link to post
Share on other sites

Tim as far as why ingot number one didnt work out I would assume it's all 4 of the options including a 5th which would be assuming too many variables which is why ingot number 4 was made much more simply and more repeatable I have large chunk of wrought I used for the test and I used white cast window weights for the cast. I had both grey cast and white cast but I heard that white was better it was more likely to form carbides.

 

Will

Share this post


Link to post
Share on other sites

Will, you need to test for Carbon which XRF cannot detect.  Any carbon determination using XRF is a subtractive amount and is worthless.  Basically they use the elemental profile to guess at what your steel is and that can pinpoint your carbon, but yours isn't a standard steel and so they have nothing to compare it with and any carbon figure is a sum of all the errors in the detection of the other elements... worthless.  You need to get Spectral AA analysis for all elements or you need to get Leco analysis for carbon, sulphur and then use XRF for Phosphrous, Silicon, vanadium, manganese etc.  XRF is still not very accurate so the Spectral analysis is much better.  We are talking about very small amounts here.  You only need 0.05% Phosphorous for the ingot to develop cold shortness and not much sulfur to get hot shortness.

 

Grey cast iron increases the silicon level in the ingot which can cause formation of graphite in the ingot so white is definitely best...

Share this post


Link to post
Share on other sites

To add to what Tim said:  You may want to ask if they can run an OES (Optical Emission Spectrometry), as that is the most common form of testing that is going to be quick and easy (cheap) that will still tell you what you need to know.  Even then it may not be 100% accurate, as calibration to an unknown specimen gets difficult.  Many XRF do not read P, Si, Al, and similar light elements (think Ca and above are a no-go).  And any form of cast iron is going to be very much a grab bag of chemistry; Forrest Gump would be amazed at what the phrase "you never know what you're gonna get" can really mean.  

Share this post


Link to post
Share on other sites
4 hours ago, Jerrod Miller said:

You may want to ask if they can run an OES (Optical Emission Spectrometry),

 

AA stands for Atomic Absorbtion and it is a kind Optical Emissions Spectrometry.... Just the old time word for it :)

Share this post


Link to post
Share on other sites

So I'm a bit confused still on if I had to give them an ideal list of elements to look for what is typical to look for besides.

 

Carbon sulphur phosphorus silicon vanadium manganese aluminum copper calcium. Thanks guys I'll be sending some pieces off for analysis within the next week. My plan was to test puck one which failed and puck four which was made with all known materials to see if I calculated carbon close to correct. As well as my consolidated bloom iron to know what I'm working with there.

Share this post


Link to post
Share on other sites

So the pieces are out for testing and if all goes well I should be able to get the atomic absorption test done and possible oes as well to confirm results as this is not a steel this company will be familiar with. They are mostly focused on types of stainless alloys but my understanding is it is quite a large company. 

 

My friend is going to get these tests done "off the cuff" so to speak. I ended up sending a piece of my orishigane from bloom iron. The bloom iron I used for the orishigane and also the most successful wootz puck to date I was able to forge it to a .5x 1.25 by about 6inch long so far and only one or two small cracks I've needed to address. 

 

One comment was brought up to me that I haven't been doing so far. Before the roast does anyone grind their puck to remove any pock marking from the crucible and/or the cap on the top where the glass and top meet. 

 

Thanks

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...