Cast iron and wrought iron

[icykarma]

Now I'll put this forward now, I don't know much about blacksmithing. It's only become a very recent hobby and interest of mine so I have a lot to learn. I'm lucky to have a relatively decent amount of mine-able (from the perspective of a poor man with too much time on hand) amount of magnetite on my property. Because of this I've picked up blacksmithing and swordsmithing. This morning I had an interesting idea that's been bugging me all day. In the same way that a katana is made with "low" and "high" carbon steel, could not a sword also be made of cast and wrought iron? Say you put a bunch of pieces of cast iron between two slabs of wrought iron, forge weld them, and fold them a bunch of times. Would this make a practical blade? Would it be possible to do? I know people say cast iron is too brittle to forge, but I just find it requires a much lighter hand to shape. But even if you can shape it to a sword it is too brittle to be useful, so why not combine wrought and cast iron? What do you think?

[dablacksmith]

true cast iron has a lot of carbon and is brittle and would be real hard to forge weld... having said that it would work if you could get it to weld... basically by doing the same as any damascus and folding and folding.it really isnt practical tho...there are much easier ways to get carbon in your damascus billet even using junk... as far as having mineable ore it really dosent pay unless your going to go way big .... i know there are smiths making theyre own steel but its just for ego and fun not practical at all ... ive seen this prosess and the cost for the amount of steel is really high .. were talking 100+ dollars per lb plus labor ... much cheaper easier and better product to buy steel.

[icykarma]

Eh, money isn't an issue for me. As I said, I'm poor. Cost effective is very different in my eyes. I have all that I need to make it. I can make my own charcoal/coke, mine my own ore, and forge my own tools. $0 plus hours of time making the materials vs $7.50 an hour 40+ hours a week plus the month or longer it would take to have enough money to buy the materials plus actually forging what I want? Tell me which is more cost effective for a poor man.

[MLMartin]

I'm would think that it would make a pretty poor blade. Many types of cast iron just crumble to bits when heated to forging temp. Also cast iron will not hold much of a edge, cast iron is full of carbon but its not homogenous with the iron. The carbon is in little pockets and not mixed cleanly with the iron. Wrought iron has little to no carbon so wont hold a edge ether. If you can get the two to laminate I'm not sure what you would end up with.

If you do want to make steel for blades you can however make your own blister steel. This would go along the lines of taking wrought iron and ground up carbon rich material, and heating them together for long periods of time. Folks have talked about this on this site before. I'm sure you can get some good information here on making blister steel.

I think if you want to make your own steel, making blister steel would be the a better option than using cast iron

[icykarma]

Thanks man, good solid advice. I think I may just try this out just to see if it can be done and what I can get. You never know, it might become the next craze! (joking...sorta) That's sort of what I was wondering about. The action of repeatedly folding does just that, spreads the carbon throughout the blade/tool/etc, right? It may not work like that since I can't be the first one to think of trying this out.

[icykarma]

The wrought iron being fairly soft and giving (the elasticity of the blade) with the cast iron being very sharp, but brittle. The combining of the two and distribution of carbon from the cast iron would make a blade with properties of both but still inferior to steel. At least, that's what's going through my head with this. From what I read about katanas they're just doing the same thing with different types of steel.

[dablacksmith]

Eh, money isn't an issue for me. As I said, I'm poor. Cost effective is very different in my eyes. I have all that I need to make it. I can make my own charcoal/coke, mine my own ore, and forge my own tools. $0 plus hours of time making the materials vs $7.50 an hour 40+ hours a week plus the month or longer it would take to have enough money to buy the materials plus actually forging what I want? Tell me which is more cost effective for a poor man.

as far as buying steel ... 7.50 a hr will buy you a lot of steel for a days work ... does your property run to fireclay? how about a good blower?making your own steel is neat but dont pretend its anywhere cost effective ... steel runs a buck or two a pound and the work involved in making your own just to make a run is a few hours after everythings setup ! its not a question you would ask if you ever saw the work it takes to make your own steel...especially if you havnt done much (or any) smithing..good luck

[icykarma]

Kid, don't test waters you haven't been in. A life of factory jobs and construction working makes steel making a fun past time. This isn't a place to question what I do or why I do it. Leave it at that.

[David Einhorn]

Mr. Icykarma, I believe what people are trying to politely tell you is that trying to use the material called "cast iron" by metalworkers to make blades is a complete waste of your time no matter what process you use. This is because cast iron in its basic structure is weak, and combining it with other layers of metal will never make up for that weakness .... unless you plan on re-smelting the iron and changing its basic structure.

Using condescension for people trying to help you does not improve matters.

[icykarma]

Half the posts mine, one who explains something politely, two who criticize me. Very polite indeed...people these days. You still haven't given me what I've asked several times. If katanas use different grades of steel that are also hard and brittle and combine them to create a katana can you not do this with cast/wrought iron? You say cast iron is structurally weak but does not combining it with wrought iron strengthen it? Why not? Have you tried this combination yourself and gotten results that would say it won't work? I'm not trying to be condescending but I find it hard to believe people who just say "well that's how it is!" I've dealt with many such people who were wrong throughout my life.

[David Einhorn]

....weak but does not combining it with wrought iron strengthen it? Why not? Have you tried this combination yourself and gotten results that would say it won't work? ...

Absolutely not. In no way can simply layering wrought iron with cast iron would it strengthen cast iron. Cast iron is structurally little itty bitty balls of iron that barely hold together. Wrought iron and steel are basically comprised of threads of iron that interweave to form structurally sound bars and flats. Cast iron is like glass while wrought and steel are like plywood. Layering plywood between layers of glass does not prevent the layers of glass from being very fragile. We know this by knowing the molecular structure of the various forms of iron, and also from years of experience. People are trying to advise you based on their understanding of the molecular structure of the metals mentioned and their years of experience. How would we know that gluing layers of thin plywood between layers of glass would not prevent the layers of glass from fracturing if the resultant sword was smacked against a hard object ... logic, the plywood would flex resulting in the glass fracturing. Sandwiching cast with wrought, the same would happen, the wrought would flex while the cast layers would fracture. You would have to change the basic structure of cast iron into something else before it could be used in a blade.

People are just trying to save you from wasting your time. Layering will not work. If you want to try it for yourself you have our blessing and our best wishes. This is my best effort to explain it. If my best effort is inadequate then I apologize but can only conclude that a more understandable and convincing explanation would be beyond my ability.

[Steve Sells]

There is one use I know of for that combination. Use 75% to 80% wrought and 20% to 25% cast iron, Melt them, as in liquify in a crucible, into a uniform mass. Adding in some carbide formers like chrome alloy steel will help. this will make an interesting blade steel.

[icykarma]

Well, yes, the glass is still weak but is very sharp. If formed right and with just the right amount being shown and protected then it is darn deadly. You seem not to be able to expand to the view I see it as. From what I can tell cast iron is harder then steel but so brittle that it doesn't really make it advantageous. Just as exposing a thin layer of sharp glass could slice most people with ease and no damage to the glass, would it not be worth making? Have the right ratio of cast iron folded on a single edged side would give an extremely hard (while I admit brittle, but humans aren't hard to cut) yet mostly protected cast iron edge. Am I wrong?

[icykarma]

Sorry if the last post is a bit condescending...old age gives you a sharp (pun intended) tongue at times.

[fciron]

Umm, I'm not sure what the cast/wrought discussion has to do with mining your own ore. If you want to make your own steel from your own ore, why not refine it directly into steel or iron rather than into cast iron?

I believe you'd be interested in the bloomery process or the traditional Japanese method of making steel, both of which produce forgeable metal. Refining ore into cast iron before making it into steel is a very recent development in the history of metalwork.

If you have forged material that you thought was cast iron in the past then I think you're mistaken about the metal. It could have been cast steel, malleable iron or even drop-forged steel.

Since you have mentioned katanas several times as the sole example of 'damascus' type steel I'm going to suggest that you look up a few knife forums and do a lot more research on damascus and pattern-welded steel. (I don't do that work, but I believe D Fogg knives has a very popular forum where people discuss stuff like bloomery steel-making and pattern-welding.) There are a lot of people out there doing very innovative work and katanas are just the razor-sharp tip of the iceberg.

Last but not least, if you've got a crazy idea that you think might work and no one believes in it then the best thing you can do is try it and take pictures. Trying to convince online skeptics is a pointless activity, and I've noticed that trying to dissuade online idealists is just as unrewarding. Perhaps that's why so few people have posted.

[Nakedanvil - Grant Sarver]

Would have taken less time to just go out to the forge and try it. Vaguely remember something, somewhere that strips of iron with a small gap were dipped into molten cast iron. Kept at a good heat the carbon will migrate from the higher to lower content material. Often when making steel by one of the bloomery processes there are areas that qualify as cast iron. The whole thing is drawn, folded and welded several time to homogenize everything. Get off the computer, quit day-dreaming and get your butt out to the forge. Then you can come back here and show these guys what-for.

[Bentiron1946]

Being a fellow that likes a good fire I say good for you and go for it. All that can happen it you will fail the first time out and as you stated you will have lost nothing but some time and as you have stated you got lots of that. I have seen some videos on You Tube where fellows in Africa are making there own iron blooms and then forging them out into such things as hoes, adzes, knifes and other such things with reasonable success. With enough time you will be successful in you endeavor. I eagerly look forward to pictures of your failures and successes. Don't let the nay sayers get to you, listen to your heart and God's speed to you. B)

[icykarma]

Thank you guys for the encouragement. I'll post some pics in a week or two.

[David Einhorn]

...and protected then it is darn deadly. You seem not to be able to expand to the view I see it as. ... iron folded on a single edged side would give an extremely hard (while I admit brittle, but humans aren't hard to cut) yet mostly protected cast iron edge. Am I wrong?

As long as the sword does not come in contact with something hard causing the blade to flex, such as another sword or knife, bone or muscle. Anything that causes flex will then break the blade. Cutting is one thing, but having a blade to reuse again later... well that is another consideration.

As for age, well I have been a hobbyist-smith for over 38 years so I am not exactly young.

[bigfootnampa]

I think you might want to consider the whole chemistry of cast iron before committing your time to a project such as this. Please also consider that for each and every one of us mortal beings, life and the time of our lives, represent very limited resources... we ALL ought to keep that in mind as we choose the ways in which we will spend our hours. I am wondering if you have considered which type of cast iron you might want to use for your experiments? Gray, white, malleable or ductile? Or perhaps some more exotic formulation? Here is a link to help decode the differences, in case you can't really tell.

Cast Iron

The idea of mixing wrought iron and cast iron to make steel is certainly not unworkable (not new either as the Chinese were doing it around 200 AD). The question is whether pattern welding is a reasonable method for creating such alloys. I think you'll find that it has been done and is doable... but not real easily done.

Here is another link to the most informative article that I have ever read on the whole subject of pattern welded steels:

The Road to Damascus

[icykarma]

If you want to offer your knowledge do so with patience and humility, please. I don't think the whole blade would break as the edge will contain most of the cast iron and even that will be folded with a fair amount of wrought iron. As the wrought iron is softer and more giving it should make the edge last longer then just cast iron while still having a sharp edge, but we'll just see. This is just a project for fun to see if the concept would work, that's all.

[icykarma]

I don't think any of you realize I'm not doing this to create steel. I'm doing this to see if this combination would be comparable to a steel blade without all the hassle of making steel itself.

Edit* "some of you"

[pkrankow]

The finished blade will be high carbon steel if you do it "right," around .8% carbon.

Cast iron is an iron/carbon alloy with over 2% carbon. Steel is an iron/carbon alloy with less than 2% carbon. Wrought iron typically has less than 0.1%

Knife making steel has around .8% carbon in it as the properties of this percentage is very simple to work with.

As carbon content goes up iron becomes "hot short" or will want to crumble and break at heat. This is in part because carbon reduces the melting point of iron.

Traditional wrought iron is iron that has had the majority of the carbon burned out of it, making it very simple to work with. This either started with a bloom, somewhere around 2% carbon, or with pig iron (a form of cast iron), with over 4% carbon.

I recommend that you start looking at some phase diagrams for iron/carbon as well as doing some research on the topic of iron and steel making. There are a large number of out of print books available for free download that cover all aspects of this during the 1800's and up until the Bessemer process of making steel became the norm.

Good luck. I am sure you can be successful at this.

Phil

[Ed Steinkirchner]

In my experience cast iron isn't brittle because it is hard, it is brittle because of the small pockets of carbon causing points at which a fracture can form. Cast iron will not hold an edge like carbon steel. So essentially, using WI and CI would yield a blade that has brittle, yet soft, spots and a soft and tough base. Unless the carbon migrates enough to make them both into High carbon steel by taking some of the C in cast iron and giving it to the wrought iron, the blade will have 2 soft bases, 1 of which is brittle, and no edge holding. If you do try this you run the risk of not only burning your shop down, but splashing molten cast iron on yourself. I only say this because the high welding temp of WI will be above the melting point of the CI and when hit, SPLATTER!
I'm not saying don't try, I'm saying be Incredibly careful.

Good luck

Ed Steinkirchner

[pkrankow]

I just recalled a technique described for making trade knives during colonial times. The smith would forge out a knife blade from wrought iron, then use a thin piece of cast iron with the wrought iron blade at welding heat take the heated cast iron and "crayon" the cast onto the wrought, effectively making a layer of hardenable steel on one side of the blade. The blade was then chisel edge sharpened to maximize the life of this very thin layer.

These knives were considered very cheap and were used for Indian trade.

Phil