A different way to make steel by...

[Randy S]

Hi Ramir

The clay I used was a clay we have around here in abundance. It's a sticky red clay with some layers of sand in it. I've made pots from it and fired them in the kiln with good results. It used to be used here a lot to make bricks for the coke ovens.

I'm not sure if the pottery clay you mentioned would hold up to the heat, but personally I'd try it and see.

 

Randy

[Skip Williams]

I had a try at this over the weekend and consider my efforts to be a success!

...

Thanks gents for bringing this to us!

Randy

 

Randy,

Perfectly done. It always amazes me that this works, it's just too simple.

 

Thanks to Don for keeping this forum going. This is our small donation in return for all the great information you all have presented here over the last few years.

Edited October 9, 2008 by ferrognome

[Ramir]

Thanks, Randy. I have asked because I had a doubt about thermal stability of usual red clay. If to consider that in the centre the temperature reaches 1600C.... Possibly the temperature in front of walls is more low if your furnace made from usual clay has not melted Very remarkable design of the furnace, my congratulations to the author of idea!

[Greg Thomas Obach]

nice furnace Randy !

and efficient too ! ( i think )

 

did much of the bore get thinner... or is there enough to fire it more...

 

Rolling green hills, wrought iron, refractory clay... Randy, you live in a fantastic place...!

 

it snowed abit here, yesterday .... ( wheres that lousy global warming people are bragging about... ???)

 

 

G

[Randy S]

Thanks Greg

There was some erosion inside the furnace but it could easily be used again as is. I'll add another sacrificial liner and have another go at it soon.

 

 

Randy

[matt venier]

I was curious about something. If this method can work with rebar/mid steel which could have a monkey mix of alloying elements in it. would it work with higher carbon steel like 1065/W1/1095 or would the extra carbon get you into making cast iron? I'm just thinking I have a lot of scrap/offcuts and stuff I bought when I was young and foolish about making hamons(1065).

 

Matt

Edited October 9, 2008 by matt venier

[Skip Williams]

would it work with higher carbon steel like 1065/W1/1095 or would the extra carbon get you into making cast iron?

 

Hi Matt,

Good question.

 

No one really knows the answer. This furnace design (with the angled blow hole) is totally brand new and Randy Skidmore and I are the only two folks who have run experiments with it. There are a half dozen folks in Europe who are experimenting with similar furnaces all using a horizontal blow hole. The current opinion from Europe is that the carbon content might be self limiting somewhere around 1 percent.

 

Come join the steel making revolution and try this yourself.

[matt venier]

Hey Skip

Let Me tell you I all ready have all the makings to do a Jesus style smelt, IE: 100lbs of iron oxide powder, Portland cement, vermiculite, white sand to make fire bricks, all kinds of black iron pipe for air supply, ETC. I've been waiting for some cooler weather and some free time. Now that this concept has come along I've been rethinking how I'm going to approach this. I figure a bunch of small experiments would be the smarter way to go than doing an all or nothing big smelt. Do you think I could use the Spanish red iron oxide that I've all ready bought in a furnace like yours? I'll post pics when I get mine built.

 

Matt

Edited October 10, 2008 by matt venier

[Skip Williams]

Do you think I could use the Spanish red iron oxide that I've all ready bought in a furnace like yours?

 

Matt,

You already have all of the materials, run the full sized Jesus style smelt. It'll work and you'll be happy you did it. Jesus is making great steel this way. This little furnace was designed for melting iron and converting it into steel and it does its job well, but I don't think it'll work with iron ore, the air is blowing so fast that the Spanish Red will end up all over the ground and all over you.

 

With the red oxide that is left over after the Jesus smelt you can try to master a teeny tiny bloomery like the one here http://iron.wlu.edu/reports/Teenytiny.htm

[Randy S]

Here is the steel I made in the little furnace after I flattened, broke it up and welded the pieces together. I did things pretty much as Jesus did but only folded it to about 80 layers.

 

http://i313.photobucket.com/albums/ll369/R_Skid/100_1728.jpg

 

The carbon is a little low, but I started with wrought iron which had no carbon. I've got some ideas for the next try

 

Randy

[Matt Bower]

Please forgive a probably dumb question from a guy with almost no forge welding experience. I've seen a number of online tamahagane demonstrations and all of them -- including this one -- contain one aspect that I don't really understand: the iron/steel chunks are covered in scale after the initial smelting/forging process, and that scale doesn't seem to be cleaned off before they're welded up into a billet. Yet apparently they still weld. How does that work? I've always read that cleanliness is really important in forge welding. I realize that the flux in the billet will help remove the oxide layer, and the clay coating (if present) will help prevent further oxidation. Even so, this all seems to fly in the face of everything I've read. Can someone enlighten me here?

[Jesus Hernandez]

Cool looking steel in that blade Randy.

 

Please forgive a probably dumb question from a guy with almost no forge welding experience. I've seen a number of online tamahagane demonstrations and all of them -- including this one -- contain one aspect that I don't really understand: the iron/steel chunks are covered in scale after the initial smelting/forging process, and that scale doesn't seem to be cleaned off before they're welded up into a billet. Yet apparently they still weld. How does that work? I've always read that cleanliness is really important in forge welding. I realize that the flux in the billet will help remove the oxide layer, and the clay coating (if present) will help prevent further oxidation. Even so, this all seems to fly in the face of everything I've read. Can someone enlighten me here?

 

Matt, what you call "scale" is in actuality "slag" from the smelting process that remains attached to the steel. In other words: flux. The steel that comes from this types of processes is self-fluxing for the first few forge-welding cycles. Once it becomes consolidated into a bar it behaves like "regular" steel from the mill and it will require more care in keeping the surfaces clean and the addition of borax or other flux.

[Matt Bower]

Thanks, Jesus. That makes absolutely perfect sense. How do you keep those flux layers from forming inclusions? Do they just get extruded from the steel during the repeated welding and forging cycles, like much of the slag in wrought iron?

[Jesus Hernandez]

Thanks, Jesus. That makes absolutely perfect sense. How do you keep those flux layers from forming inclusions? Do they just get extruded from the steel during the repeated welding and forging cycles, like much of the slag in wrought iron?

 

I would say yes to that but I will qualify the answer by saying that I am not sure that all of the slag gets out of the billet.

[Jziegenbein]

that's awesome! definitely need to try that sometime soon, once i get my forge built.....

[Monty]

Fellas what a great thread!

Till now the idea of smelting my own steel seemed too difficult to attempt on my own. However this thread has made everything seem a lot more simple and achievable.

 

I like that "direct" approach on that other link that Skip posted. Plenty of fun to be had here , methinks!

[Skip Williams]

Here is the steel I made in the little furnace after I flattened, broke it up and welded the pieces together. I did things pretty much as Jesus did but only folded it to about 80 layers.

 

 

The carbon is a little low, but I started with wrought iron which had no carbon. I've got some ideas for the next try

 

Randy

 

Randy,

I have a few ideas for you but I'll wait to post them, you may prefer to solve this problem on your own.

 

Aristotle's Meteorology says this about making steel (translation by Radomir Pleiner)

 

... wrought iron indeed will melt and grow soft (like water) and then solidifying again, and this is the way in which steel is made. For the dross (the slag) sinks to the bottom and is removed from below, and by repeated subjection to this treatment the metal is purified and steel is produced. They do not repeat this process often, however, because of the great wastage and loss of weight in the iron that is purified. but the better quality of the iron, the smaller the amount of impurity.

 

Back in those days they though that steel was the pure form of iron and wrought iron was impure. To some extent they were correct, wrought iron contained 5-10% fayalitic slag. Melting and separating the slag from the iron allows the iron to absorb and retain carbon.

[Randy S]

" repeated subjection to this treatment the metal is purified and steel is produced"

 

This is what I was thinking... spark the steel after breaking it up and run the lower carbon pieces through again.

I also built my furnace shorter, only about 8" deep inside. I think a deeper furnace would have helped bring the carbon content up due to more time in the stack.

But then maybe it just needed to sit longer in the bottom of the furnace to gain more carbon?

I need to build a few furnaces and experiment some more.....

 

Thanks again Skip, this kind of process is very interesting to me.

 

Randy

[Skip Williams]

This is a photo of some high carbon steel that was made in this furnace from soft iron rod. The total ingot weighs 750gm and the whole ingot sparks the same, short small traces that burst into a super feathery shower within 4-6 inches from the wheel.

 

I don't have any metallurgy books here at home so I'm not sure what the image is telling me. anybody?

 

 

Photo details

The ingot was cut with an abrasive wheel.

The exposed face was honed on water stones from 320 grit to 8000 grit.

Polished with Chromium oxide

The sample was then etched for 5 minutes in dilute HCl

The image was taken with a hand held digital camera positioned over the eye piece of a dissecting microscope.

Edited November 13, 2008 by ferrognome

[Jesus Hernandez]

Skip,

 

That looks very similar to this photo taken at a lesser magnification from one of my bloomery smelts a while back:

 

 

I think that it is an indication that the metal was liquid at one point followed by slow cooling allowing for carbide segregation.

 

Very cool picture!

 

 

 

Edited to say: Oops! I was not paying attention to the scale on your picture. Let's see what those with metallurgical knowledge think.

Edited November 13, 2008 by Jesus Hernandez

[Skip Williams]

Jesus,

Thanks for confirming what I'm thinking. I see the same cementite on the macro scale as you do, the cementite needles in this ingot are visible without magnification, at least to a younger eye. A big difference in our steels is that this ingot solidified in about 10 minutes while your tatara steel probably had a lot longer cooling time in the furnace so my needles are shorter.

 

Now for some fun.

I did a little image analysis with Adobe Photoshop to calculate the carbon content of this steel. It looks like maybe 15% cementite. When the numbers are run through the calculator I find that this steel is 1.6% percent carbon.

 

A selected area in the steel. Same image with the cementite colored red

[Dmitry.M]

When the numbers are run through the calculator I find that this steel is 1.6% percent carbon.

Could you tell us how you estimated the carbon content in the cementite? As far as I remember there are several cementite types with different carbon-iron ratio. Is there some formula? And what carbon content you use for calculations for the "black" pattern on the picture?

[Skip Williams]

Dmitry,

The cementite is 6.7% carbon. I assumed that everything else is pearlite, the number I used is .77% carbon.

 

.85 * .77 + .15 * 6.7 = 1.7% (plus or minus .1%)

 

There are several sources of error with my method that are likely to throw the result off by a couple tenths of a percent either way. Firstly the quality of the image isn't very high, I'll fix that with my next camera purchase. Second, I'm using a 'calibrated eyeball' to judge what is cementite and what is not. I'll have to try this with a couple of known samples of 1.2% to 1.6% steel before I can assert its accuracy.

 

Here's a picture of the ingot I'm working on

Edited January 8, 2009 by Skip Williams

[Dmitry.M]

Thank you , ferrognome. I tired something very similar, but my eyeballing was not so good. So I gave up on this method.

 

Do you know any place to send the sample for the spectrometer analisys? The cheaper - the better...

[matt venier]

Well I built a little furnace and had two runs with it and had some pretty good results. I built mine a little bigger than skips, a 6" bore and almost 14" high. I would show you pictures but my choices of refractory on hand were few and the furnace didn't survive the second run ( as a side note, portland cement, sand and some vermiculite will not hold up to getting the ingot out ) but out of two runs I got these.

 

ingot #1 2lbs mix of high carbon and low carbon

 

ingot #2 3lbs almost all high carbon with a couple of smaller separate chunks of high carbon I ran the furnace a lot harder and let it burn longer before getting the ingot out.

 

So at this point I have 5+ pounds of steel and I very happy! I going to build a new furnace, so I'm wondering what refractory ( bought or home brewed) would be best to hold up to the rigors of ingot removal, and my other problem is the amount of sparks that come shooting out of this thing. I'm running my air supply pretty hard and there's a lot of velocity, could I open up the blow hole and get more air with less pressure? or should I make the stack taller? Thank you Skip for sharing this idea with the forum I enjoy being able to experiment with this without having to deal with large cash outlay for charcoal and ore.

 

Matt