The Epic Interactive Encyclopedia 1998/Epic Interactive Encyclopedia, The - 1998 Edition (1998)(Epic Marketing).iso/M/Metallurgy/INFOTEXT

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The science and technology of producing
metals, which includes extraction, alloying,
and hardening. Extractive, or process,
metallurgy is concerned with the extraction
of metals from their ores and refining and
adapting them for use. Physical metallurgy is
concerned with their properties and
application. Metallography establishes the
microscopic structures that contribute to
hardness, ductility, and strength. Metals can
be extracted from their ores in three main
ways: dry processes, such as smelting,
volatilization, or amalgamation (treatment
with mercury); wet processes, involving
chemical reactions; and electrolytic
processes, which work on the principle of
electrolysis. The foundations of
metallurgical science were laid about 3500 BC
in Egypt, Mesopotamia, China, and India,
where the art of smelting metals from ores
was discovered, starting with the natural
alloy bronze. Later, gold, silver, copper,
lead, and tin were worked in various ways,
although they had been cold- hammered as
native metals for thousands of years. The
smelting of iron was discovered about 1500
BC. The Romans hardened and tempered iron
into steel, using heat treatment. From then
until about AD 1400, advances in metallurgy
came into Europe by way of Arabian chemists.
Cast iron began to be made in the 14th
century in a crude blast furnace. The demands
of the Industrial Revolution led to an
enormous increase in wrought iron production.
The invention by Henry Bessemer of the
Bessemer process in 1856 made cheap steel
available for the first time, leading to its
present widespread use and the industrial
development of many specialized steel alloys.