wrought iron

[Alfie]

I was just idly reading through some wikipedia entries on early smelting techniques, and saw an article on the refining of pig iron.
M thought was that if you can accidently 'burn off' carbon in steel by taking it above welding temperature (I have 'killed' the hardenability of some knife steels by getting them too hot), could you not hold mild steel at that heat for a predescribed time at a temperature above welding heat, thus making a 'wrought iron' ish material.
I am pretty confident I am wrong, but It was puzzling me, so I thought I would put it before y'all.
Alfie

[KevinD]

I've wondered the same thing. I'm looking forward to some more informed responses.

[ptree]

Wrought iron also has silicon and graphite stringers/inclusions that are a large part of its nature. Just burning out the carbon will not add the silicon and graphite.

[dablacksmith]

you could do this and get something similar to what is called "pure iron" .. not sure what the bonus would be tho.... mild or lo carbon steel works well enuf and dosnt have the problems wrought can have .(wrought iron has a grain and can split along the grain.) i just dont see tgoing thru the hours it will take to get the carbon out for marginal gain... mind as well buy the "pure iron"!

[Quenchcrack]

Wrought iron is the product of a bloomery furnace. This furnace is a precursor to the modern blast furnace but it lacked any way to force air (and thus oxygen) into the furnace. Because of that, it did not get hot enough to actually liquify the metal. Iron was produced by reacting iron oxide with carbon monoxide that resulted from burning coke or coal in a low oxygen environement. What resulted was a big blob of metal mixed with the melted limestone, silica from the iron ore, and irregular inclusions of carbon. The entire mass had to be pulled out of the furnace and worked (thus the name "wrought) into a useable form. The working squeezed out some of the impurities but much of the silica stayed and the extra carbon got oxidized away. Wrought iron is basically pure iron mixed with silica stringers. While the bloomery process is the simplest and oldest method, the puddling process uses cast iron from a blast furnace and mechanically entrains slag into it while decarburizing the iron to produce what is also called wrought iron.

Edited January 1, 2009 by Quenchcrack

[bipolarandy]

Quenchcrack, you must try these newfangled things people are reading, they are called books...
Alfie, short answer, yes, long answer , not in your shop. Around the late 1700's a prosess called Puddling was developed in which the raw pig iron from a blast furnace was fed into a large rectangular furnace that had a fire box off to one side, normaly heated by coke or charcoal, the pig iron used had around 3-4 % carbon and high amounts of silicon, phosphorus and manganese, so not quite mild steel. So, once all the bar have melted in the fire pot, the mass is stired around and oxidized untill most of the silicon has boiled away, then the phosphorus, carbon and slag are removed in the same way. Once all the impurities have been removed, the iron is taken out of the furnace at and rolled in a mill or forged into bars. You could say, its a silmilar idea to the bessemer converter, only all the work is being done in one furnace, And later on when hand-puddling became obsolete this same prosess was scaled up and could make wrought iron in 5000-8000 pound batches at once.

[Ten Hammers]

Well, assuming that Quenchcrack is a metallurgist, i will assume he has read a few books. Thanks for the explanation Bob, it clears up a few things.

[Glenn]

Quenchcrack, you must try these newfangled things people are reading, they are called books...

bipolarandy, this is can be read as a personal attack.

Quench, has a degree in metallurgy and is employed as a metallurgist, maybe you should present your credentials and or site reverences to back up your posts. That way we can read the original sources for information.

[bipolarandy]

Sorry Glenn, It was ment as a joke. I was just responding to quenchcracks assumption that wrought iron can only be made in a bloomery.
http://en.wikipedia.org/wiki/Puddling_(metallurgy)
PUDDLING

[Steve Sells]

I don't see much of anything at that link, except a request for adding to it.

Also Wiki is not a primary reference for anything. When anyone 2 through 120 yrs old can post with out any credentials, or verification of fact. Its a nice place to get fast info, but without backup of real knowledge and verifiable facts, its just a chalkboard most anyone can write on.

so to your second link:
Even tho I would take the side of a metallurgist over a dictionary, at least Websters is a credible source :)

Edited January 1, 2009 by steve sells

[bipolarandy]

darn, thats why I dont use Wiki...hehe Puddling (metallurgy) - Wikipedia, the free encyclopedia

[divermike]

I was reading last night in the "edge of the anvil" that slag is still in the wrought iron, I'm assuming that is what these guys are listing as impurities, all I know is I have not yet mastered getting the stuff I have to become workable to any degree, but looking at what yellin could do with it once it is double refined, I'm not about to give up.

[bipolarandy]

i couldn't find a searchable copy online , but this my reverence.
An Introduction to the Metallurgy of ... - Google Book Search

[Quenchcrack]

When wrought iron was originally made in a bloomery, there was no blast furnace to liquify the iron and no pig iron could be made. It came out as a semi-solid as I explained in my first post. The working of that semi-solid produced wrought iron. The process you describe does not produce wrought iron as the silicon appears to have been removed while the iron was in a liquid state, a state that wrought iron does not achieve.

[Quenchcrack]

I went to this site: anvil's ring iron smelting article rather than Wackypedia for reasons already mentioned. I learned there is indeed a way to create wrought iron from cast iron. However, that is not the bloomery process. The blast furnace came much later in time and could produce large tonnages of cast iron which was recombined with the high-silica slag to form a variety of wrought iron. I don't know how holding mild steel at a temperature above the welding temperature would re-introduce the silicate stringers that make wrought iron what it is.

Edited January 1, 2009 by Quenchcrack

[Dan P.]

To clarify; You cannot make wrought iron by decarbing mild steel in a forge. I have made a simulacrum of wrought iron by melting mild steel in a charcoal fire and consolidating the crud found at the bottom, but that's a whole other waste of time!

And because I cannot help myself- The vast, vast majority of the wrought iron that ever existed on this planet was made by decarbing cast iron. The ore was reduced in a blast furnace, then converted into a workable material via the puddling process. That is a simple fact.

[Quenchcrack]

OK, referring back to the original question about making mild steel into wrought, most of us do not have a blast furnace in our back yard and could not make cast iron to feed into a puddling furnace. If we had a puddling furnace. However, there are a sizeable number of smiths (especially bladesmiths) who operate simple bloomery furnaces and produce wrought iron as they did 160 years ago. This seems then, to be the only logical way to make wrought iron if you wanted to make the real stuff at home. I would not argue that the greatest tonnage of wrought was made with cast iron. Many thanks to the people who corrected my mistake.

Bipolarandy: would you mind explaining what you meant with this reply to Alfie?: "Alfie, short answer, yes, long answer , not in your shop." Are you saying he could hold mild steel at welding temperature to make wrought?

Edited January 1, 2009 by Quenchcrack