The history of making steel

Iron was in limited use long before it becamequench-hardened steel, with only a few, probably
possible to smelt it. The first signs of iron useornamental, bronze weapons.
come from Ancient Egypt and Sumer, whereDuring the Han Dynasty (202 BC–AD
around 4000 BC small items, such as the tips of220), Chinese ironworking achieved a scale and
spears and ornaments, were being fashionedsophistication not reached in the West until the
from iron recovered from meteorites About 6%eighteenth century. In the first century, the Han
of meteorites are composed of an iron-nickelgovernment established ironworking as a state
alloy, and iron recovered from meteorite fallsmonopoly and built a series of large blast furnaces
allowed ancient peoples to manufacture smallin Henan province, each capable of producing
numbers of iron artifacts.several tons of iron per day. By this time, Chinese
Meteoric iron was also fashioned into tools inmetallurgists had discovered how to puddle molten
precontact North America. Beginning around thepig iron, stirring it in the open air until it lost its
year 1000, the Thule people of Greenland begancarbon and became wrought iron. (In Chinese, the
making harpoons and other edged tools fromprocess was called chao, literally, stir frying.)
pieces of the Cape York meteorite. TheseAlso during this time, Chinese metallurgists had
artifacts were also used as trade goods withfound that wrought iron and cast iron could be
other Arctic peoples: tools made from the Capemelted together to yield an alloy of intermediate
York meteorite have been found in archaeologicalcarbon content, that is, steel. According to legend,
sites more than 1000 miles (1600 km) away.the sword of Liu Bang, the first Han emperor,
When the American polar explorer Robert Pearywas made in this fashion. Some texts of the era
shipped the largest piece of the meteorite to themention "harmonizing the hard and the soft" in the
American Museum of Natural History in New Yorkcontext of ironworking; the phrase may refer to
City in 1897, it still weighed over 33 tons.this process.
The name for iron in several ancient languagesSteelmaking in India and Sri Lanka
means "sky metal" or something similar. In distantPerhaps as early as 300 BC, although certainly by
antiquity, iron was regarded as a precious metal,AD 200, high quality steel was being produced in
suitable for royal ornaments.southern India also by what Europeans would later
Iron axehead from Swedish Iron Age, found atcall the crucible technique. In this system,
Gotland, Swedenhigh-purity wrought iron, charcoal, and glass were
The Iron Agemixed in crucibles and heated until the iron melted
Beginning between 3000 BC to 2000 BCand absorbed the carbon. One of the earliest
increasing numbers of smelted iron objectsevidence of steel making comes to us from
(distinguishable from meteoric iron by their lack ofSamanalawewa area in Sri Lanka where
nickel) appear in Anatolia, Egypt and Mesopotamiathousands of sites were found. (Ref. Juleff, 1996).
(see Iron: History). The oldest known samples ofExport
iron that appear to have been smelted from ironThe resulting high-carbon steel, called in Persian
oxides are small lumps found at copper-smeltingand wootz by later Europeans, was exported
sites on the Sinai Peninsula, dated to about 3000throughout much of Asia. The famous Damascus
BC. Some iron oxides are effective fluxes forswords were possibly made of steel imported
copper smelting; it is possible that small amountsfrom India.
of metallic iron were made as a by-product ofA solid pillar of curiously rust-resistant
copper and bronze production throughout theiron—often mistakenly characterized as
Bronze Age.being made of steel— forged or cast in
In Anatolia, smelted iron was occasionally used forthe 4th century AD, and which has stood for
ornamental weapons: an iron-bladed dagger with amany centuries next to the Qutab Minar in the
bronze hilt has been recovered from a HatticQutb complex in Delhi, is a testimony of the
tomb dating from 2500 BC. Also, the Egyptianmetallurgical skills of Indian artisans. The metal is
ruler Tutankhamun died in 1323 BC and wasvariously described as cast iron or wrought iron.
buried with an iron dagger with a golden hilt. AnIts resistance to oxidation is theorized to be due
Ancient Egyptian sword bearing the name ofto the formation of a protective patina catalyzed
pharaoh Merneptah as well as a battle axe with anby the a residue of phosphorus in the ore.
iron blade and gold-decorated bronze haft wereSteelmaking in the Middle East
both found in the excavation of Ugarit (seeBy the 9th century, smiths in the Abbasid
Ugarit). The early Hittites are known to havecaliphate had developed techniques for forging
bartered iron for silver, at a rate of 40 times thewootz to produce steel blades of unusual flexibility
iron's weight, with Assyria.and sharpness (Damascus steel).
Iron did not, however, replace bronze as the chiefRecent research has established strong evidence
metal used for weapons and tools for severalsupporting the theory that the distinct surface
centuries, despite some attempts. Working ironpatterns on Damascus steel blades result from a
required more fuel and significantly more laborcarbide-banding phenomenon produced by the
than working bronze, and the quality of ironmicrosegregation of minor amounts of
produced by early smiths may have been inferiorcarbide-forming elements present in the wootz
to bronze as a material for tools. Then, betweeningots from which the blades were forged.
1200 and 1000 BC, iron tools and weaponsFurther, it is likely that wootz Damascus blades
displaced bronze ones throughout the near east.with damascene patterns may have been
This process appears to have begun in the Hittiteproduced only from wootz ingots supplied from
Empire around 1300 BC, or in Cyprus andthose regions of India having appropriate
southern Greece, where iron artifacts dominateimpurity-containing ore deposits.
the archaeological record after 1050 BC.Ironworking in medieval Europe
Mesopotamia was fully into the Iron Age by 900The middle ages in Europe saw the construction
BC, central Europe by 800 BC. The reason forof progressively larger bloomeries. By the 8th
this sudden adoption of iron remains a topic ofcentury, smiths in northern Spain had developed a
debate among archaeologists. One prominentstyle that become known as a Catalan forge, a
theory is that warfare and mass migrationsfurnace about 1 meter (3 feet) tall, capable of
beginning around 1200 BC disrupted the regional tinsmelting up to 150 kg (350 lb) of iron in each
trade, forcing a switch from bronze to iron. Egypt,batch. In succeeding centuries, smiths in the
on the other hand, did not experience such a rapidFrankish empire and later the Holy Roman Empire
transition from the bronze to iron ages: althoughscaled up this basic design, increasing the height of
Egyptian smiths did produce iron artifacts, bronzethe flue to as tall as 5 meters (16 feet) and
remained in widespread use there until aftersmelting as much as 350 kg (750 lb) of iron in
Egypt's conquest by Assyria in 663 BC.each batch. These larger furnaces required more
Iron smelting at this time was based on thedraft than could be provided by human power,
bloomery, a furnace where bellows were used toand forging the large blooms that resulted was
force air through a pile of iron ore and burningalso beyond the capabilities of a single man. To
charcoal. The carbon monoxide produced by thethis end, waterwheels were employed to power
charcoal reduced the iron oxides to metallic iron,the bellows and hammers.
but the bloomery was not hot enough to meltEventually, the scaling up of the bloomery reached
the iron. Instead, the iron collected in the bottoma point where the furnace was hot enough to
of the furnace as a spongy mass, or bloom,produce cast iron. Although the brittle cast iron
whose pores were filled with ash and slag. Themay initially have been a nuisance to the smith, as
bloom then had to be reheated to soften the ironit was too brittle to be forged, the spread of
and melt the slag, and then repeatedly beaten andcannons to Europe in the 1300s provided an
folded to force the molten slag out of it. Theapplication for iron casting: cast iron cannonballs.
result of this time-consuming and laboriousThe oldest known blast furnace in Europe was
process was wrought iron, a malleable but fairlyconstructed at Lapphyttan in Sweden, sometime
soft alloy containing little carbon.between 1150 and 1350. Other early European
Wrought iron can be carburized into a mild steelblast furnaces were built throughout the Rhine
by holding it in a charcoal fire for prolongedvalley: blast furnaces were in operation near Liege
periods of time. By the beginning of the Iron Age,(a city in modern-day Belgium) in the 1340s, and
smiths had discovered that iron that wasat Massevaux in France by 1409.
repeatedly reforged produced a higher quality ofThe first English blast furnace was not built until
metal. Quench-hardening was also known by this1491, when Queenstock furnace was built at
time. The oldest quench-hardened steel artifact isBuxted, followed by one commissioned Henry VII
a knife found on Cyprus at a site dated to 1100at Newbridge, in 1496 in a part of Sussex known
BC.as the Weald. Despite this late start, the
Developments in Chinaproduction of English iron foundries rapidly grew, in
Archaeologists and historians debate whetherno small part due to foreign craftsmen hired by
bloomery-based ironworking ever spread to ChinaHenry to bring the craft of iron casting to England.
from the Middle East. Around 500 BC, however,In 1543, William Levett, an English rector who
metalworkers in the southern state of Wudoubled as a Wealden ironmaster , and Peter
developed an iron smelting technology that wouldBaude, a French craftsman in Henry VIII's
not be practiced in Europe until late medievalemploy, cast the Weald's first one-piece iron
times. In Wu, iron smelters achieved acannon. English iron cannons gained a reputation
temperature of 1130°C, hot enough to befor being superior to, and less expensive than, the
considered a blast furnace. At this temperature,bronze cannons made elsewhere in Europe, and at
iron combines with 4.3% carbon and melts. As aleast initially, efforts to copy them outside the
liquid, iron can be cast into molds, a method farWeald failed. The superiority of English cannons
less laborious than individually forging each piece ofover Spanish ones has been credited as one
iron from a bloom.factor in England's 1588 defeat of the Spanish
Cast iron is rather brittle and unsuitable for strikingArmada.
implements. It can, however, be decarburized toIn 1619, Jan Andries Moerbeck, a Dutch
steel or wrought iron by heating it in air forironmaster, began importing Wealden iron ore for
several days. In China, these ironworking methodscomparison to the ore available on the Continent.
spread northward, and by 300 BC, iron was theOne difference he observed was that the English
material of choice throughout China for most toolsore contained some calcareous material, and soon
and weapons. A mass grave in Hebei province,after, Dutch ironmasters introduced the use of
dated to the early third century BC, containslimestone as a flux in the blast furnace. This
several soldiers buried with their weapons andpractice improved the separation of slag from the
other equipment. The artifacts recovered fromcast iron and improved the quality of Continental
this grave are variously made of wrought iron,cast iron.
cast iron, malleabilized cast iron, and