[TheForge] Pure Iron vs. Cast Iron

Fri Mar 28 06:38:20 EST 2008

Ekaterina,

Pure iron is just that plain iron. No alloy and No carbon.  (Carbon is 
really an alloy element but we don't think that way most times.)  As we 
start to add carbon to iron we get steel.  Low carbon is around 0.2 of 1 
percent carbon -- mild steel.  This is also sometimes called points of 
carbon or 20 points.  Most high carbon steel today is around 1 percent 
carbon (100 points.)  We often also call this a tool steel.  W1 for example 
is 1 percent carbon.  Medium carbon steels are around a 1/2 percent carbon 
0.5 of 1 percent or 50 points.  Steels may also have lots of different 
alloying elements added greatly changing their strength and other 
characteristics.  Steels can have a maximum of 2 percent carbon -- above 2 
percent carbon, we have the cast irons.  Up to I believe the max the iron 
can "hold" is 6.67 percent carbon.  Your ductile iron is one form of the 
"cast irons".  Gray cast iron another.

Historically there was a very common product called "wrought iron" sometimes 
today called "real wrought iron".  It like "pure iron" had almost zero 
carbon, maybe a very small amount.  But it did have Silicon Oxide stringers 
in it from the manufacturing / refining process.  To confuse things even 
more -- it was made from cast iron or pig iron by removing the carbon.  Same 
is true today for the manufacture of raw steel -- it starts out a liquid 
cast iron from a blast furnace -- also a lot of recycled steel is added.

Hope that helps a little.

Dave Smucker

----- Original Message ----- 
From: "Ekaterina Harrison" <ekaterina at wildblue.net>
To: <theforge at mailman.qth.net>
Sent: Friday, March 28, 2008 12:50 AM
Subject: [TheForge] Re: File Making, sniffing up wrought iron

> Hi All,
>
> I must admit that some of this is going over my head. <sigh> Perhaps  this 
> was already answered and I missed it.
> I have spent a few years working in various foundries and have poured 
> some ductile iron. However, I really did not get a chance to find out  as 
> much as I had wanted to about the various aspects of iron. Perhaps 
> somebody here can answer this - What is the difference between iron  that 
> is cast and what you are referring to as pure iron?
>
> Ekaterina
>
> On Mar 27, 2008, at 8:26 PM, theforge-request at mailman.qth.net wrote:
>
>>
>> Message: 2
>> Date: Thu, 27 Mar 2008 14:10:52 -0400
>> From: "David E. Smucker" <davesmucker at hotmail.com>
>> Subject: Re: [TheForge] Re: File Making, sniffing up  wrought iron
>> To: "Sponsored by ABANA" <theforge at mailman.qth.net>
>> Message-ID: <BAY137-DAV227345FD9B7D86414EDBCADFE0 at phx.gbl>
>> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
>> reply-type=response
>>
>> Frosty,  I believe the pure iron made today is being made via an 
>> electric
>> arc furnace.  It is really being produced as "transformer iron" for  use 
>> in
>> some types of transformer and other magnetic devices.  It is  produced in
>> sheet form.  This is quite a bit of this produced but not as much as 
>> some of
>> the other transformer irons with high Si content.  (Pure Si, not the 
>> oxide.)
>> The blacksmithing pure iron was (is) produced by taking some heats  of 
>> this
>> material and running it to bar stock.
>>
>> To the best of my knowledge there are no Bessemer Furnaces still in
>> operation.  (Air Blast)  There are a lot of Basic Oxygen Furnaces 
>> operating
>> producing about 60 % of the worlds raw steel.  Some have called BOF  the 
>> "son
>> of Bessemer" as the blast is now Oxygen vs. Air.  The BOF can take a 
>> feed of
>> about 1/3 scrap vs. little or no scrap in the Bessemer.  In the BOF  you
>> don't have to heat the N2, so you can melt scrap instead.
>>
>> Dave
>> ----- Original Message -----
>> From: "Jerry Frost" <akfrosty at mtaonline.net>
>> To: "Sponsored by ABANA" <theforge at mailman.qth.net>
>> Sent: Thursday, March 27, 2008 1:27 PM
>> Subject: Re: [TheForge] Re: File Making, sniffing up wrought iron
>>
>>
>>> This leads me to delve back into the recollections that I was  mistaken
>>> about regarding when wrought was last produced in the US. (lousy 
>>> sentence
>>> but understandable I hope)
>>>
>>>> From what I recall reading; after the bessemer process
>>> became wide spread, production of wrought fell off sharply and mild 
>>> steel
>>> became more and more the norm for construction and other things  wrought
>>> was used for. Still, there was a large market for wrought iron and  for 
>>> a
>>> period bessemer processed pure iron was sold as wrought, later  specific
>>> amounts of silica was added to make "bessemer wrought." (I'm using a
>>> descriptive phrase here, that's almost certainly not what it was 
>>> actually
>>> called)
>>>
>>> Again, my memory is probably not clear so I'm sure details are  wrong. 
>>> I've
>>> looked through my bookmarks and read myself cross-eyed but can't  find 
>>> the
>>> link I probably lost it in the last crash.
>>>
>>> Anyway, I strongly doubt fresh wrought is being produced the way  they 
>>> did
>>> it 150 years ago. The ore or scrap is probably refined and purified  via
>>> the Bessemer process and silica added back in to make up "wrought". 
>>> It's
>>> them refined under rolls rather than hammers.
>>>
>>> Pure iron is probably taken out of the process before alloying  agents 
>>> are
>>> added and actually requires less labor, materials and fuel to  produce. 
>>> But
>>> as all small batch products costs more.
>>>
>>> I'll go sit quietly now.
>>>
>>> Frosty
>>> -------------------------------
>>> If it ain't forged
>>> it ain't real.
>>> Wrought iron is.
>>> The FrostWorks
>>>
>>> Meadow Lakes, AK.
>>>
>>>
>>> From: "Andrew Vida" <osan at netlabs.net>
>>>
>>>> The front page is interesting in that mewonders if they have  confused
>>>> pure iron with wrought.  To wit, it states:
>>>>
>>>> "Pure Iron is a high-purity iron that is very ductile and the 
>>>> preferred
>>>> material for forging and decorative metal work. While very popular  in 
>>>> the
>>>> first half of the 20th century, its use was reduced by the  development 
>>>> of
>>>> new steel alloys and high production costs."
>>>>
>>>> I do not recall pure iron being popular in the era up to 1950, but
>>>> perhaps I am mistaken.  Also, referring to it as "ductile" rather  than
>>>> malleable leads me to suspect.  Wrought iron is ductile (uni-axial
>>>> deformable) whereas pure iron is malleable (multi-axially  deformable).
>>>>
>>>> Just an observation.
>>>>
>>>> -Andy
>>>>
>>
>
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