Turning steel back into pure iron?

[Will W.]

Hello everyone. 

I've had this question rattling around in my head for a few days now. My research has pulled up no answers however. Basically all available information talks about turning iron into steel, not reversing the process.

Is it possible to take a low carbon steel (basic mild steel is what I had in mind) and decarburize it to the point where it is pure iron again?

The process, in my mind, would consist of getting the piece up to ~welding heat in an oxiding fire to intentionally decarburize it. I'm not sure if the result would be *pure* iron, however, as the fuel would likely add very small amounts of carbon, even after burning through the majority of it. 

I realize it would be much more simple to just get iron from somewhere (either buying pure iron or using wrought,) but I'm just curious if it's possible. 

I use charcoal as my fuel, by the way. 

Thanks in advance!

[ThomasPowers]

well you would probably scale away the iron trying to oxidize all the carbon out of it.  As you can buy "steel" with vanishing small amounts of carbon in it it would probably be cheaper and easier to do it that way.  (There used to be a vendor of "4 ought iron"  which IIRC was .0000X% C

[Frosty]

I believe Pure Iron was bought out a few years ago but don't know if it's still available. If you want to do it yourself look into the Bessimer or (Basic Oxygen Process?)

Melting steel in a charcoal fire excess oxy or not will more likely make cast iron.

Frosty The Lucky.

[Will W.]

23 hours ago, ThomasPowers said:

well you would probably scale away the iron trying to oxidize all the carbon out of it.  As you can buy "steel" with vanishing small amounts of carbon in it it would probably be cheaper and easier to do it that way.  (There used to be a vendor of "4 ought iron"  which IIRC was .0000X% C

True. I figured after a certain point, all of the carbon would have scaled away, leaving behind only the iron. Didn't figure on them going down together (so to speak.)

I guess I may be better off trying to locate some wrought iron. There are plenty of old farms in my area. I'll see if I can offer my "clean up services" to them. 

Don't get me wrong, I still want to try this. There's almost no way to tell if I have a burnt piece of mild or pure iron left over, but still, good chance to learn something, I guess. 

22 hours ago, Frosty said:

If you want to do it yourself look into the Bessimer or (Basic Oxygen Process?)

Melting steel in a charcoal fire excess oxy or not will more likely make cast iron.

I knew a little bit about the Bessemer process before, but your post made me research it, and I learned quite a bit. That alone deserves a thank you. 

There's no way I want to melt steel though. That's way too dangerous, considering my set up. 

[WayneCoeArtistBlacksmith]

Speaking of your "clean up service", a blacksmith that I know in North Georgia saw an old barn just full of old stuff and trash.  Thinking that he might find something worth while in the barn he decided that he would offer $250.00 for the contents.  He went up to the house and knocked.  When the older lady came to the door he said,, "Mam, I'll clean out your barn for $250.00."  She said, "Just a moment, young man, and I will get my check book."

That story still gets told around blacksmith meetings.

Wayne

[ThomasPowers]

Don't assume your wrought will be very low carbon!  (much is but not all---remember they have been quench hardening wrought iron swords since around the first century AD.  Read "The Celtic Sword" Radomir Pleiner for some examples of early ferrous sword metallurgy also "The Metallography of Early Ferrous Edge Tools and Edged Weapons", Tylecote & Gilmour)

[Will W.]

14 hours ago, WayneCoeArtistBlacksmith said:

When the older lady came to the door he said,, "Mam, I'll clean out your barn for $250.00."  She said, "Just a moment, young man, and I will get my check book."

Lol that's a pretty funny story, thanks for sharing. 

 

Thomas

I do not know very much about wrought iron, so thanks for the knowledge. I'll have to see if I can get my hands on the books you mention as well. 

[rockstar.esq]

Will W.

Based on steel I've unintentionally burnt, I can't imagine the fireworks involved in trying to "render" the carbon out!  The little bit of charcoal I've used sends up "fire fleas" something fierce. 

To my mind, this is a bit like breaking concrete to recover the gravel. 

[Philip Typaldos Waters]

I'm pretty sure the steel is going to scale away like several other posters mentioned.

The carbon and steel atoms both are happy to "burn" and you'll probably wind up with a lot if iron oxide at the end of your attempt.

Historically wrought iron would also have had varying levels of silica slag mixed in with the iron as well. This is what gives wrought iron it's noted rust resistance and fiberous structure. Later wrought iron would have had less or even negligible amounts of silica slag.

If you want the low slag wrought iron the very low carbon steel is probably your best bet and you can buy that. If you want higher silca slag wrought iron burning out the carbon in mild steel wouldn't get you what you want even if it worked.

I'd really like to try smelting my own at some point.

[ThomasPowers]

Look into the Byers process where pretty much at the end of the Wrought Iron Era they made it by taking molten Bessemer/kelly steel and added slag to it and mixed it hydraulically...