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Scott A. Roush

Crucible steel... Preliminary opinions?

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I have a project in which I need to make a blade from an old cast iron plow share from a customer's farm so I did an experiment in a crucible with the broken pieces of plowshare and taconite pellets. And a dash of pure nickel.

 

I just got this out of the crucible a few hours ago and am wondering what the experienced folks think of the surface appearance. The outside sparks like low-medium carbon..

 

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11121775_10204908561972975_1951213652623

 

10271504_10204908561812971_2002608654481

 

Just curious what people think before I start cutting it or forging it. It's so beautiful to me that I really don't even want to mess with it.

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My experience is that the outside may not spark like commercial steel bar. That you have those sparks at all is promising for a knife, but the challenge now (which I'm not nearly experienced enough to offer advise on) is to get it to a point of being able to forge it. Thermal cycling, gentle heat, gentle blows, 1/8" at a time, is the general target I understand as appropriate... have fun!

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Thanks Christopher.

 

I'm curious about what the surface texture can say about the quality of a melt. The beautiful waves and there are also linear structures.

 

I did just cut the cake in half and am etching it right now.

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Getting a first right puck out is exhilarating, but don't succumb to the thrill, its even more thrilling try to forge it. Yours looks just fine, with plenty of straight dendrites, and a bubbly appearance which probably means you managed to get rid of the air in the melt. Dendrites are carbide needles, that are teh straight lines you see there. Actually looks like some good ones others have posted! I guess the advice would be to take it low and slow, i.e. keep it below about 960 C and move it real slow so it doesn't get stressed, but can't say more, as we have hit a wall at that point here in Greece! Good luck!

 

P.S. Let your hammer pound, and in any case you can remelt it, now that you've got the hang of it?

Edited by Athan Koumantos

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Getting a first right puck out is exhilarating, but don't succumb to the thrill, its even more thrilling try to forge it. Yours looks just fine, with plenty of straight dendrites, and a bubbly appearance which probably means you managed to get rid of the air in the melt. Dendrites are carbide needles, that are teh straight lines you see there. Actually looks like some good ones others have posted! I guess the advice would be to take it low and slow, i.e. keep it below about 960 C and move it real slow so it doesn't get stressed, but can't say more, as we have hit a wall at that point here in Greece! Good luck!

 

P.S. Let your hammer pound, and in any case you can remelt it, now that you've got the hang of it?

 

Music to my ears! I can see the dendrites coming up in my etch now...

 

And yes... I can remelt after I buy a new crucible and make a new furnace. :D This was their last stand. I did a bunch of direct ore reductions before attempting this that were pretty hard on my stuff.

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So what would I have gotten here if I had not put in that little slug of pure nickel?

 

Up until now I've sort of placed all of this crucible stuff in the back of my mind. But these results compel me. Time to LEARN.

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Hot Damn Scott!

That sure is purdy!

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Thank you...

 

Well I've done some thermocycling and will plan to try it under the hammer later today.

 

Another point of interest.... I really took no effort to slow cool other than to leave it in the furnace and vaguely close up the holes. My furnace was on it's last legs and had developed so many breaches that I really didn't achieve much by trying to close it up. So... makes me interested in the slow cooling that you hear so much about. I think I saw a reference in Mitchel's thread as this being one of the differences between 'wootz' and 'bulat'.

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If Jeff Pringle were to get on and comment on this, he would say few if any of his ingot are "slow cooled". As to whether this makes any difference, I'm not sure. Once everything's liquid, and killed of oxygen, I think you want to go to solid right away. The old stories are probably not much than a reflection of the types of furnaces they were using, and a lack of urgency we tend to live with. If you're doing 20 of these in a larger, charcoal-burning furnace, you might stay away for a day or two until everything cools down and you can reach in there with your hands. I'm willing to bet 5 cents that it's not a major force in the type of steel one gets, having seen some excellent patterns deeply reminiscent of the old ones being produced in modern furnaces, and removed right away.

 

As for the nickel you added, it's just one more element in your mix. I find (in using nickel-rich meteoric iron) that it tends to inhibit corrosion nicely. There was some debate earlier in whether it slows down carbon migration in a layered billet, but in a fully melted environment, I suppose it will just give you some interesting contrast and machinability qualities you wouldn't have had without it. I wouldn't suggest it's "better" or "worse" one way or the other, just different. I like the pattern that's showing up in your etch, and can't wait to see this forged out. Good luck!

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Scott,

Go slow and hope for a lot of resistance to forging...once that leaves it is too late. If you are forging at a relatively high temperature ( but a safe one ) it is easy with some tools to add to much energy to the metal during forging...this will take it to an unsafe zone and the metal will fail. Do not hang around at one spot while forging move around to distribute that energy ( = heat). If you are thinking of pressing it you will have to take the tiniest bites you can and the piece should always stay in compression under the dies. I would not start off with a machine forging until at leat 10 -15 cycles of hand forging.

 

Good luck

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Thanks guys.... I appreciate it. Very excited to start forging.

 

As to the nickel.... So Christopher do you think it's presence is related to or affecting the pattern? I've started accumulating some research papers.... including the one on 'impurities'.. that one seems relevant. Hope to learn more soon...

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The chemistry always matters, in that it affects what you see. But a wide variety of chemistries work, and there isn't one single recipe that makes the "perfect wootz." Even in antiquity, there were lots.

 

I think (and my own efforts reflect this) that keeping the inputs simple, and getting the melting and forging down consistently, is the way to begin. Once one can master the forging of an ingot, and the ingots are coming out pretty much the same, then it's time to play around with what goes in there, and see what differences you get, both in appearance, and in how it works under the hammer.

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Thanks Christopher.

 

Well... The puck, as Jan says, certainly resists forging. More so than any material I've ever encountered. A hand hammer barely even affects it. This COULD be due to my paranoia regarding forging too hot. I would never forge as cool as I was this particular piece. My TC was reading 750- 800 C.. but it is a bit higher and further back in the forge than where I was keeping the ingot.

 

I couldn't resist taking a little bite with my press and I immediately cracked it. But fortunately it was a shallow crack and I ground it away.

 

Anyway.. Other than thermocycling through my light, cold hammering I achieved nothing.

 

Tomorrow I will try again and weld a handle on.. I was struggling with holding the piece.

 

I'm also starting to question my evaluation of the spark pattern. I assumed that the longer streams with subdued fireworks was lower carbon steel... but now I'm wondering if the pattern falls more in line with 'malleable iron' as they are more orange than white in color. Could be due to the nickel present as well...

The chemistry always matters, in that it affects what you see. But a wide variety of chemistries work, and there isn't one single recipe that makes the "perfect wootz." Even in antiquity, there were lots.

 

I think (and my own efforts reflect this) that keeping the inputs simple, and getting the melting and forging down consistently, is the way to begin. Once one can master the forging of an ingot, and the ingots are coming out pretty much the same, then it's time to play around with what goes in there, and see what differences you get, both in appearance, and in how it works under the hammer.

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I did some more forging and came to the realization that it can't be THIS hard to forge. I mean... hand hammering was doing nothing despite a bit higher heat. So I decided that since I have the other half of this ingot I might as well do some destruction. So I forced the issue under the power hammer with a piece and it fell to pieces. The grain was HUGE and looked much like cast iron does when trying to forge it.. and this despite the 10 or so thermocycle heats. So I then did some more careful spark test comparisons and my ingot seems to fall in the 'malleable iron' category.

 

So... it seems like from what I've been reading that it isn't out of the ordinary to work an ingot that is this high in carbon by slowly bringing it down via roasting, thermocycling and careful hammering? At what point is it worth pursuing? Or would it be best for me to break it all up and re-melt with a little more iron (and maybe a vanadium source)??

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And... here is that nickel I added. :D

 

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Okay folks.... I'm really struggling with the forging.. which I expected. It's not like I haven't been warned. :) But I'm trying to get a feel for how much these ingots should actually move in the early stages. I'm keeping my forging temps in the 700 - 800 C and nothing happens at all. It's like hitting black heat. Is this what is expected for a high carbon wootzy ingot?

 

The first half is in pieces.. mostly because I felt like it was a good idea to push boundaries and see what I could get away with. You simply cannot use the press after 5 or 6 heats. I know this now. I still have one larger chunk of this particular piece that seems to be without cracks. I found a reference to a Verhoeven article detailing his use of iron oxide for decarburizing the outer layers of his ingots. Basically covering the ingot with iron oxide and soaking at 1200 C for 10 hours. So.. I've done this except not as long. I had a much smaller piece so I gave it only 2 hours. I left it in the furnace to cool and resume forging tomorrow. But.. was this even necessary? Is it best to just keep light hammering cycles going until the piece starts to move??? Hammering with nothing happening seems to me to be just a way of continuing thermocycling and facilitating the decarburization process.

 

Anyway... I'm hoping to figure this out before moving on to the other half of this ingot. My intuition tells me that I should consider a re-melt due to the slug of nickel found right in the middle of the ingot. But other than that.. the inside is so clean and free of voids. So...?

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Going back through and reading everything here and elsewhere that I've gotten advice.. somehow I've missed the '1/8" rule'... so slow moving indeed. I apologize for sort of re-asking that in the above post.

 

I've given it a shot most of this day and have made almost no progress... I've had a few pieces break off again and I've been able to get those to move a little easier.... but I'm rapidly losing material. I suppose there is a point at which you just have too much carbon?

 

One thing I'm trying to understand. Wootz and related materials are very high carbon steels.. but you are basically shooting for something that is closer to cast iron in the actual ingot and then through either thermocycling, 'roasting' and very, very slow forging... you bring the carbon down. Am I interpreting this correctly? I mean.. could you just skip the light forging and and just do many, many thermocycles to achieve the same goal??

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Forging it out is difficult, I've never had much success with it either, I usually start off slow cool, then towards the end, I start getting restless and going hotter and hitting harder, and "well maybe I'll just gently draw it out on the press" it always fails. I think, just like everything else, it requires experience with the material, and in this case, it's difficult to start over :( not sure if "extra" thermocycling will help out, some ingots are just difficult

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Sorry to hear about the difficulties. I'm still fighting with a piece of iron I made last year. I think that's just because of my improper anvil (15lb piece of rail turned on end sitting on a 6x6 with about an inch by 3 inches I think) and my inexperience. I'd be more than willing to send it to you if you wanted to fool with it lol.

 

It's a shame about the nickel not behaving right either.

Edited by M. Cochran

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First let me say seeing all the work you have done I am confident you will get a handle on crucible steel. It is definitely a tedious process. I am currently forging my first decent ingot after roughly 20 forging cycles its just now squaring up some. I could not get the ingot to move until I bumped it up to around the 1700F range and moved to a 4Lb hammer, still working it slow though. I think decarbing is more for just a skin to try to keep cracks from starting, than reducing the overall carbon content. Just a thought maybe if the better section of ingot does forge out you could do a jelly roll with thin wrought stock and stuff all the ingot crumbles in between and weld it in a press. Looking forward to what this becomes!

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First let me say seeing all the work you have done I am confident you will get a handle on crucible steel. It is definitely a tedious process. I am currently forging my first decent ingot after roughly 20 forging cycles its just now squaring up some. I could not get the ingot to move until I bumped it up to around the 1700F range and moved to a 4Lb hammer, still working it slow though. I think decarbing is more for just a skin to try to keep cracks from starting, than reducing the overall carbon content. Just a thought maybe if the better section of ingot does forge out you could do a jelly roll with thin wrought stock and stuff all the ingot crumbles in between and weld it in a press. Looking forward to what this becomes!

Thanks Brandon. Yes.. I've been thinking of doing something like you suggest with the crumbles. Something like teko-gane. But didn't think to roll it up!

 

Well... after doing some research.. I'm starting to wonder about the cast iron in the plowshare. I haven't found a source indicating if grey cast iron was being used for plowshares in the 19th century... but I suppose that grey iron may have been more appropriate in terms of toughness. I see information regarding 'chilling' the edge to reduce carbon and things like that. And the spark testing is confusing.. it doesn't seem to fall perfectly in any category according to the charts.

 

But if it does turn out to be grey iron? Is it even worth pursuing?

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Oh well... :-) I've received help privately. I have a new plan now.

 

Thanks for listening and thanks to those who have offered some advice.

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Another attempt using the cast iron plowshare but wrought iron nails instead of taconite. :-) Might as well make things easier on myself.

 

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That is a nice looking ingot! Does this one have nickel in it as well? I hope it makes it through the forging!

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