Red short

[silverclaws]

Ok, I have just found a description of what my lump of sea recovered iron chain does when heating to red heat and attempting forging, it crumbles, and yes at the visible grain lines, called I believe red short in metalsmithing terms, high sulphur bearing metal. As to where this sulphur came from, could it be in the metal as it was forged, or did it come later by being immersed in estuary mud for a hundred years or two, I don't know.

Though I can use the metal like this for another purpose, that of wonderfully organic looking jewellery, I would like to know, is there a process that can be applied to increase the plastic properties of the metal and reduce the crumbling at red heat.

Hmm, come to think of it, exactly how old is this chain, was it not the invention of the reverberatory furnace by one of the Darby's in the eighteenth century that first was able to create iron without high levels of sulphur included. If my chain was first forged and it included the high sulphur content, it might be pre 1800's.

But, is there any way to make the stuff more plastic in a basic forge ?

Edited October 10, 2009 by silverclaws
reverbatory and refractory aren't the same thing, it's been a long time since school

[David Einhorn]

Your best bet is to try forging it at a white welding heat or close to white heat. The lower the quality of the wrought iron the hotter you will likely need to forge it.

[matt87]

This may echo UnicornForge a little...

I've not yet got around to forging wrought, but the received wisdom is to work it as hot as you can; it's not steel so it burns at a higher temperature -- white is typically mentioned.

[irnsrgn]

low quality wrought like in iron wagon tires, needs to be hammered at an orange heat several times to draw out the flux used to refine it, then you can work it at higher heats, if you work wrought to cold (red) it will split. have you spark tested it, it could by an off chance, be cast iron, as it crumbles when trying to forge it?

[silverclaws]

Spark Test ?

I assume the metal is wrought, with all the already gone to earth crumbly bit burned off in the forge, and one link sand blasted, I can see the way the thing was made, it has a clear scarf joint at one end I assume to be fire welded. But to be honest, I am not au fait with many hot working processes, as my normal discipline, is non ferrous metals, silver, copper, brass etc. All I know about a spark test, is for deciding whether a piece of metal has carbon in it, by watching the sparks from a grinder.

I will try and post a photo of one of the links tommorrow, in the hope the visual appearance might give some clues. One bit of metal I did manage to forge out of it, is not with me at the moment, that sits in a drawer at college. I will get that and post a photo after Monday.

One thing I have discovered though, this stuff is fairly corrosion resistant, as, bare metal just hanging around develops a skin of rust in no time, especially in my place, it being damp, ( constant battle to keep my burnishers pit free ) but the forged bit hasn't started to rust, though the chain link I have here, has rusted a bit in places, but no way as much as I would have thought it would have done.

[orgtwister]

may be its some type of bog iron but then again im not an expert but i've seen bog iron laying around for years that really aint rusting bad i know they used bog iron for stuff on old ships like rivits and washers

[David Einhorn]

Old wrought iron tends to have silica in it. When the iron rusts down to a layer of glass formed by the silica, the glass stops the rusting, thus the strand-like texture when the rust is removed. If the glass is broken, the rusting is likely to progress further.

[Mark Emig]

I secon Unicorn forge's opinion. When forging wrought iron I start at a white heat-near welding temperature-when the surface looks wet and glassy- and more importantly stop forgeing in the mid orange range. If true wrought iron is forged too cold it will almost always split, crumble and generally behave badly.
Mark Emig

[Dave Budd]

Silverclaws, I see you are in the Devonshire Countryside. If you like you can bring a lump over to my forge sometime and we can see if there is some sense to be made of it

I don't claim to be an expert (I'm not arrogant enough to claim expertise in anything I do), but I do work with various wrought irons and steels regularly so I may have used something that reacts similarly :)

[Mark Emig]

I second Unicorn forge's opinion. When forging wrought iron I start at a white heat-near welding temperature-when the surface looks wet and glassy- and more importantly stop forgeing in the mid orange range. If true wrought iron is forged too cold it will almost always split, crumble and generally behave badly.
Mark Emig

[Mark Emig]

One other quick note as to the quality of wrought iron. You can almost always tell the quality of wrought iron by what it was used for. For instance, wagon wheels were low quality iron, as all a wagon tire had to do was resist abrasion. Chains are almost always high quality iron, as chain needs to be tough and strong to do its job. Bridge iron is another good source for high quality iron also. It sounds like you are just not working the material at the proper temperature as you state that it crumbles at a "red heat". Get it HOT before working it.
Good luck!
Mark Emig

[ThomasPowers]

A few misconceptions: What Abraham Darby accomplished was the commercial smelting of iron from ore using coke instead of charcoal---all charcoal iron was very low in sulfur; but when they tried smelting with coal the high levels of sulfur made the metal unusable. So the iron for the previous 1000 or so years was very low sulfur (though sometimes high in phosphorous).

Also the definition of wrought iron is that it's a composite material of a usually a clean iron and ferrous silicates---if it doesn't have the silicates it's not wrought iron! The lower quality wrought irons do tend to have a greater percentage of silicates and those in larger form.

[Charles]

Forge it driping you will need to basicly always reweld every heat or it will be hot short it is normal to forge wrought like this dont be frightened to get it hot it will be very soft and easy to work should come up like new good luck

[silverclaws]

A bit belated, but I now have a picture of the stuff in question. The picture shows one of the ''as found '' links, minus a bit, one of the links after burning off the rust in the forge, and final bit, the straight piece, is one of my first attempts at forging the stuff, one can notice where the crumbling has started and I backed off. Another piece I had, it just crumbled away into bits which when cool, just looked like bits of orangey brown earth. Just to note, the straight bit on the photograph, has not rusted since I did it, back in the spring. All I did with it post forge, was sand blast it and scrub it with a wire brush, the finish is as is, a light grey bordering on silver and rust free.

Edited December 19, 2010 by Moderator42

[ThomasPowers]

Rust damage may be so severe that the first thing you need to do is to re-consolidate the wrought iron by forge welding it back together