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Joining the madness...


Bill Schmalhofer
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Please check out this explanation of the Ellingham Diagram from MIT.  

 

One thing I neglected to mention is that the Ellingham-Richards chart is all very dependent on exposure to free oxygen.  Inside a solid mass of metal you still rely on diffusion for things to move, then at the surface you have the opportunity for these reactions.  A liquid state allows much faster movement of elements to get to the surface.  From there you have to have free oxygen to reach the metal.  With induction melting we can keep this from happening with the SPAL process, where we drip liquid argon onto the liquid bath.  The argon expands greatly and displaces all oxygen, therefore no oxides!  The bigger reason this is often done is to keep the nitrogen out.  

 

Borax is sodium tetraborate decahydrate, Na2B4O7*10H2O, with the Na2B4O7 being the important bit.  Apply the principles of the chart above to the Na and B in borax and you will see that both like oxygen more than iron; or at least you would if they were on that chart.  But their reaction is definitely below iron, so they will preferentially strip the oxygen from iron oxide if the conditions are right (temperature and partial pressures).  This would also be true for lines above the iron line, but not necessarily any below the iron line, and keep in mind that the lines aren't all parallels to each other, so different things will be preferential in different conditions.  

 

BTW, there are also diagrams for things besides oxides, like sulfides.  Neat stuff.  

 

Carbon boils happen at a variety of temperatures, depending on the chemistry of the bath.  It generally happens when there is too much rust (iron oxide, and note that different forms of iron oxide have different lines on the chart) in the base charge so the reaction starts.  We stop the reaction by throwing a little ferrosilicon or aluminum in the bath to preferentially react with the oxygen.  No oxygen in the bath means the carbon isn't able to convert to CO.  

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That's just too cool, Jerrod!  Thanks for the explanation.  I'm stuck in the 19th century, science-wise, when it comes to smelting/remelting.  

 

And "Liquid Argon Drip" would be a great name for metal band...

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5 hours ago, Alan Longmire said:

And "Liquid Argon Drip" would be a great name for metal band...

Second that!:lol:

 

OK so no borax! Maybe that's what I was actually watching - not steel turning liquid but all the slag and extra borax leaking out. Still was really cool to see. Just wish I could have videoed it.

6 hours ago, Jerrod Miller said:

BTW, there are also diagrams for things besides oxides, like sulfides.  Neat stuff. 

VERY neat stuff. Again, second Alan's comment "That's just too cool".

I was wondering where Na and B fell on the graph. Do they fall above or below Cr?

 

This is a serious rabbit hole that I'm going to have to go down - but not tonight. Been up for 17 hours on 4 hours of sleep.

 

Thanks to you both for all the information.

 

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Na is way low on the graph, should be lower than Ca; very reactive stuff.  B looks to be just below and parallel to Mn.  Keep in mind though we aren't interested in just Na and B.  We have to consider a reaction/state that is lower energy than Na2B4O7.  So it is not going to be 4/3B+O2 = 2/3B2O3, We are going to be looking at something like Na2B4O7 + 1/2O2 = 2NaO + 2B2O3, or something along those lines, not too familiar with boron oxides.  At any rate that would be a completely different line.  It could even break down into something else that is some version of NaxByOz before dropping again to separate Na and B oxides.  And the difference between those energy states may mean that there is now something else in between.  

Ellingham diagram for oxides. | Download Scientific Diagram

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As the late Larry Harley once said to the late Al Pendray during a crucible smelt (direct reduction of ore in a sealed crucible), "It's more than just a bunch of fat old men watching a fire..." :lol:

 

I'm lucky to have been standing beside them at the time.

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Thanks Jerod

 

the MIT definition helps when explaining the graph is upside down. I keep wanting to add solid  carbon to the CO/CO2 ratios at those temperatures..I am not sure if that is the case or the numbers are just an actual measurement of added quantities.

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  • 5 months later...

So colder weather is upon us and I now have a chance to fire back up the hearth furnace. During the break away from this I made a new base for holding the bricks.1_IMG_0218.jpg

It's made from cast-o-lite 3000 with a core (not shown) of inswool 2600. Molded spaces for the bricks to fit them nice and tight to make it easier to get the wire around without having to struggle. Worked so well I almost didn't need the wire. Used it today for its maiden voyage and it worked beautifully.

 

Had planned on 5 runs but due to mishaps with an experiment I tried, I only got four completed runs in. The experiment was to try and seed in a small amount of rice sized anthracite coal into the burn. Seemed to be going OK until I pulled the puck from the furnace. It was riddled with little bits of coal and broke apart when I hit it with a hammer. So the second run was actually running the material from the first run again - WITHOUT coal.

 

Starting material for the first three runs was grinder swarf packed tightly in 6 oz tomato paste cans. Was able to pack 150-200 grams of swarf in each can. Made the runs as 1 kg total loads. Yield was 571 g (no surprise with having to run it twice), 777 g and 726 g. The fourth run was the mild steel bar cut-offs from all my damascus billets. Total load was 1020 g and final yield was 941 g. There were good omens on my last run because as I was just starting the first charge I noticed two adult Bald Eagles flying over me. Was really cool. I wasn't able to get pictures of them, but my wife did.

 

Final pucks run order from top to bottom.

3_IMG_0226.jpg

 

All of them packed nice and tight when consolidated on the stump.

 

And the spark tests:

 

#1

5_IMG_0228.jpg

 

#2

6_IMG_0230.jpg

 

#3

7_IMG_0232.jpg

 

and #4

8_IMG_0236.jpg

 

The nicest part is these don't seem to be bi-polar this time. I don't know if it was a case of the base being so insulated it helped keep the heat in, or if it was because I had angled the tuyere at a bit steeper angle to keep more of the charcoal glowing -  or a combination of both. Regardless, I now have just over 3 kg of what appears to be (relatively speaking) homogeneous high carbon steel to work with.

 

Just have to wait for a relatively warm day to consolidate them.

 

Edited by Bill Schmalhofer
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Nice run Bill!

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“So I'm lightin' out for the territory, ahead of the scared and the weak and the mean spirited, because Aunt Sally is fixin’ to adopt me and civilize me, and I can't stand it. I've been there before.”

The only bad experience is the one from which you learn nothing.  

 

Josh

http://www.dosgatosdesignsllc.com/#!

https://www.youtube.com/channel/UCdJMFMqnbLYqv965xd64vYg

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As I was digging through my stuff, I "found" the 3.5 Kg of "wrought iron" pucks that I had made when I was doing the demo at Conner Prairie. Had completely forgotten about this stuff. It was made chiefly of bottle caps and it didn't turn out very good (read high carbon - sparks as pure iron)) as I think we were using a poor set up (indestructible, heat impervious bricks that were a major heat sink - they were still hot after 3 hours of "cooling down"). But wrought does have its place in things. Needless to say, I have a LOT of consolidating to do...

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  • 6 months later...
Posted (edited)

Finally got some time to try to consolidate the high carbon pucks from my last hearth furnace run. Had very variable results.

 

Starting material (not in the same order as the bars).

1_Pucks.jpg

 

Noticed something strange on the largest of the pucks. It has been sitting in a fairly cool dry environment since November and it has developed these white crystals on the surface. Only this one had it and all the pucks were stored together. Any thoughts?

2_White crystals.jpg

 

6 hours later, the variable results:

3_bars.jpg

 

From RIGHT to LEFT.

 

First puck did NOT want to weld to itself. No matter what I did, it just wanted to crumble on me. But it does still spark nicely. To me the sparks look like little explosions not the branched sparks we "normally" see. 

4_spark 1.jpg

 

Second one was welding fine, but I got hasty and screwed up the third fold weld and had some cracks form. Looks like a bit of carbon loss. Will see if I can break this apart and clean it up.

5_spark 2.jpg

 

Third bar was acting a bit like the first but not quite so bad. Got two folds on this one and decided to put it down instead of fighting it. Sparks are nice though, looking like some pretty high carbon. Thinking of trying to clean this up too and mixing it with the the second bar.

6_spark 3.jpg

 

Fourth bar (the one that came from the puck with the white crystals) acted beautifully. Consolidated down to a bar nicely and then was able to get four rounds of welding done (8 layers). Ended up with a bar about 8 x 1.5 x 0.25 inches and all the edges, and the flats that I checked, spark like this picture. Very happy with this and I think I will move this forward into a knife (unless there is a consensus that it is still maybe a bit high in carbon and should be welded one or two time more).

 

7_spark 4.jpg

 

As a final note, I checked all the edges of the three bars that made bars, and they all seem to be homogenous (basically the sparking looked the same no matter which edge was tested). On the whole, am pretty happy with how these are turning out. 

 

Edit:  The match up between the hearth runs and the bars:  Run 3/ "bar"1; Run 1 / Bar 2; Run 2/ Bar 3; Run 4/ Bar4 

Edited by Bill Schmalhofer
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20 minutes ago, Bill Schmalhofer said:

white crystals on the surface.

 

Maybe you fluxed that one with a bit of borax?  That's what it looks like when it leaches off an overfluxed weld, anyway...

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1 minute ago, Alan Longmire said:

 

Maybe you fluxed that one with a bit of borax?  That's what it looks like when it leaches off an overfluxed weld, anyway...

I don't think it could be. The only time I use borax now is when I'm welding these billets together after making them into a initial bar. I usually cut hot an fold when doing these (thus the need for some flux), but other than that, I have become a flux-less forge or furnace (also except for axes...). Maybe material from the fire bricks? No idea what they are made of...

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There’s a lot of crazy chemistry out there….once when some magnesium snuck into my aluminum scrap I ended up with this bizarre growth on the slag I scooped off the top….it looked like mold growing on the metal ( video is sped up)

 

 

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I'd recommend taking that bar to a higher layer count to help decarburize and also homogenize it a little more. I tend to shoot for 12 folds with this material for Japanese work, 8 for Viking age stuff. I think Kevin Cashen did a test with the stuff that found after about 4 folds you even out carbon content in a bar. When you continue to fold you lose carbon content by exposing the surfaces to oxygen, then as you continue folding the average carbon goes down little by little. I find that a bar that sparks like you're second or first photo in your recent post is a good candidate for hardening, but it is hard to judge from just pictures. Maybe the best bet is to cut a small coupon of your 8 layer bar, and forge something small from it. Harden in water and see what happens, then adjust from there. 

 

Either way good luck with it! This material is not easy but it is very rewarding to work with 

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Posted (edited)
4 hours ago, Emiliano Carrillo said:

I'd recommend taking that bar to a higher layer count to help decarburize and also homogenize it a little more. I tend to shoot for 12 folds with this material for Japanese work, 8 for Viking age stuff. I think Kevin Cashen did a test with the stuff that found after about 4 folds you even out carbon content in a bar. When you continue to fold you lose carbon content by exposing the surfaces to oxygen, then as you continue folding the average carbon goes down little by little. I find that a bar that sparks like you're second or first photo in your recent post is a good candidate for hardening, but it is hard to judge from just pictures. Maybe the best bet is to cut a small coupon of your 8 layer bar, and forge something small from it. Harden in water and see what happens, then adjust from there. 

 

Either way good luck with it! This material is not easy but it is very rewarding to work with 

Thanks for the advice. I stopped at 4 folds (16 layers actually - math was never my strong suit :blink:) because every thing was going so well I didn't want to mess it up by "doing one more weld". I will take your expert opinion and run it through a few more times. I actually was worried it may have still been a bit high in carbon.

 

Any advice on the first puck that just seemed to want to crumble? 

 

Also, I have about 3.5 Kg of material from hearth furnace runs that all spark as almost pure iron. Any advice on consolidating them? I'm thinking I'm going to consolidate them into one bar and use it for a couple of ax / hawk bodies.

Edited by Bill Schmalhofer
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  • 1 month later...

Good stuff here Bill. This is a great project.

“So I'm lightin' out for the territory, ahead of the scared and the weak and the mean spirited, because Aunt Sally is fixin’ to adopt me and civilize me, and I can't stand it. I've been there before.”

The only bad experience is the one from which you learn nothing.  

 

Josh

http://www.dosgatosdesignsllc.com/#!

https://www.youtube.com/channel/UCdJMFMqnbLYqv965xd64vYg

J.States Bladesmith | Facebook

https://www.facebook.com/dos.gatos.71

https://www.etsy.com/shop/JStatesBladesmith

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