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Re: different iron alloys (was Re: What is the best free software for creating & editing PDFs nowadays)

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Kragen Javier Sitaker <kragen@canonical.org> writes:

> Sam Plusnet <not@home.com> writes:
>> On 31/08/2026 09:11, Bertel Lund Hansen wrote:
>>> I question that. Wikipedia has an article about cast iron and
>>> another one about steel. Though both kinds have iron plus
>>> impurities, their properties are sufficiently different to earn
>>> different names - and more important, different uses.
>>> 
>> Iron may 'suffer' from impurities, whilst steel contains carefully
>> controlled 'impurities' which are selected to give it the preferred
>> properties.
> 
> It's quite a bit more confusing than that.
> 
> References to unqualified "iron" before the 19th century, and sometimes
> thereafter, almost invariably refer to wrought iron.
> 
> Wrought iron (which is no longer manufactured commercially, not since
> Thomas Walmley and Sons shut down the Aston Forge in Bolton in England
> in 01973) overlaps with mild steel in composition, but has a different
> macrostructure, with slag inclusions giving it a fibrous structure and
> reducing its susceptibility to corrosion.

It's common for blacksmiths to refer to the material they work with
for ordinary work -- ornamental, sculptural, horseshoes, general
whatever -- as "iron" altough they all know it's "mild steel", not
wrought iron or pure iron.  Most smiths have some degree of
familiarity with iron alloys with differing properties.  Those making
cutlery, tools, machine parts, anything where heat treatment is part
of the regime, become very knowledgeable about alloys.

A noteworthy point about how "iron" -- mild steel -- is sold: Up to
sometime in the last 50 years, m/s was designate by SAE numbers that
indicated the amount of carbon in the material offerd for sale.  SAE
1010 had ten points of carbon. SAE 1040 had forty points.  Blacksmiths
routinely looked for SAE 1010 or SAE 1020 because the strenth was
suitable for most all uses and te lower carbon content meant it was
easier to forge.

But currently, steel is sold with a different rating (I forget the
institutional source) but the number isn't based on the carbon
content.  It's based on the tensile strength, a factor much more
inportant to structural engineers.  But the result is that the ease of
hand-forging isn't predictable from the numerical designation by the
vendor.  Malleability can vary from similarly designated batch to
batch while the tensile strength still meets the standard.

> In the specific case of *cast* iron, "iron" *also* "contains carefully
> controlled impurities which are selected to give it the preferred
> properties".  In fact, the main impurity in both cases is carbon.  Cast
> iron has quite a bit more of it (over 2%) than steel; low-carbon "mild"
> grades of steel can have as little carbon as wrought iron does.  Roughly
> speaking, the usual ferrous grades are something like this:
> 
> - 0-0.1% carbon: wrought iron
> - 0.05-0.3% carbon: mild steel
> - 0.3-2.1% carbon: carbon steel
> - 2.1-4.5% carbon: cast iron
> - 3.5-4.7% carbon: pig iron (rarely seen outside foundries)
> 
> Also, if you have 10.5% or more of chromium, it's "stainless steel",
> even if it has no carbon.
> 
> Cast iron normally also contains silicon to improve its casting
> properties.
> 
> From the perspective of anyone who has studied this stuff, the above is
> a terrible oversimplification, since there are hundreds of grades of
> steels, with dramatically different properties, and different pieces of
> steel may even have the same composition but dramatically different
> properties due to heat treatment.
> 
> This is almost certainly off-topic for alt.usage.english at this point,
> but which of the still-active newsfroups would be best for it?

alt.crafts.blacksmithing or rec.crafts.metalworking (which is fairly
busy but mostly frequented by machinists.)


-- 
Mike Spencer                  Nova Scotia, Canada

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Re: different iron alloys (was Re: What is the best free software for creating & editing PDFs nowadays) Mike Spencer <mds@bogus.nodomain.nowhere> - 2026-09-13 18:31 -0300

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