METAL PROPERTIES, CHAR, USES, AND CODES - OD1643 - LESSON 1/TASK 1
It is possible, by varying the carbon content and by proper heat
treatments, to alter properties from a very soft, workable steel, of
the type used in pressed metal parts, wire, and similar materials, to
hard, strong steel, suitable for use in tools, machinery, and armor,
where great strength and hardness are necessary.
(5) Cast Iron.
Cast iron is produced by melting a certain
quantity or charge of pig iron, limestone, and coke in a cupola
furnace.
It is then poured into sand or alloy steel molds, and
allowed to cool at room temperature. Cast iron is basically an alloy
whose chief elements are iron, silicon, and carbon. The material is
available with a wide range of properties. Pig iron, gray cast iron,
white cast iron, chilled cast iron, and malleable cast iron are all
referred to as cast iron.
(6) Wrought Iron.
This is the oldest form of iron made by man.
It is a metal that contains high purity iron and iron silicate. It
is very low in carbon with the iron silicate or slag distributed
throughout the base metal in fibers. These fibers give the material
a woody or stringy appearance when broken.
(7) Differences Between Cast Irons and Steels.
(a) All the various forms of cast iron, steel, and wrought iron
consist of chemical compounds and mixtures of iron, carbon, and
various other elements in small quantities.
Whether the metal is
classified as cast iron or as one of the steels depends entirely upon
the amount of carbon in it.
The following table illustrates this
principle:
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