Railroads and the Transformation of the Iron and
Steel Industry
The Basics
Iron and steel only differ by the amount of carbon they contain.
Steel is an intermediate alloy between Wrought Iron that contains less
than 1 percent carbon and Pig Iron that contains between 2 and 4 percent
carbon. Steel contains approximately 1 to 2 percent carbon.
Essentially wrought iron was made until about 1300AD. There are
iron implements found in Egypt that date to about 3000BC and the technique
of hardening iron weapons by heat treatment was known to the Greeks by
1000BC. In the ancient method a mass of iron ore and charcoal was heated
in a forge or furnace having a forced draft. The ore was reduced to a
sponge of metallic iron filled with a slag composed of metallic impurities
and charcoal ash. The sponge of iron was removed while still incandescent
and beaten with heavy sledges to drive out the slag and to weld and
consolidate the iron. This produced iron containing 3 percent slag
particles and .1 percent other impurities. By accident this technique
could occasionally produce steel.
After 1400AD larger furnaces were used with an increased draft.
This resulted in the iron taking on more carbon forming
pig iron (so called because it was usually cast in stubby,
round ingots known as "pigs").
Iron ore,
coke, and
limestone form the "charge".
The coke gives off carbon monoxide as it burns that in turn combines with
the iron oxides in the ore reducing them to metallic iron. The limestone
also is a source of carbon monoxide and serves as a flux to combine with
the infusible silica in the ore to form fusible calcium silicate. The
calcium silicate and other impurities form the slag that
floats on top.
Diagram of a Blast Furnace c. 1940
Railroads and the Iron Industry
In 1874 railroads used about 150 tons of iron per mile (rails
and rolling stock). Prior to the Civil War the American iron industry was
simply inadequate to supply the needs of the railroads.
Between 1840 and 1860 over 60 percent of railroad rails were
imported from England. Indeed, before the Civil War a major activity in
the American iron business was re-rolling used rails! That
is, re-heating the worn iron rails (mostly British) and re-rolling them so
that they could be laid back down.
The American iron industry was so poor that an inferior batch
of iron in Wales was dubbed "American" iron. However, by 1890
all this had changed. Pig iron production almost tripled between 1880 and
1890 and by 1910 the U.S. output was 27 million tons compared to Britain’s
10 million tons of pig iron. By the outbreak of World War I, the U.S.
produced more steel than Britain and Germany combined. By 1900 steel rails
were less than $20 a ton and almost all the railroad rails in the U.S. were
steel. What happened?
Andrew Carnegie.
