METAL PROPERTIES, CHAR, USES, AND CODES - OD1643 - LESSON 1/TASK 1
aircraft structures, railway cars, electrical transmission lines, and
kitchen utensils are made of aluminum.
(b) Capabilities.
Aluminum can be cast-forged, machined, and
welded.
(c) Limitations. Direct metal contact of aluminum with copper
and copper alloys should be avoided. Aluminum should also be used in
low temperature applications.
(2) Chromium.
The chemical symbol for chromium is Cr, and its
ores are chromite and chrome ochre.
(a) Uses.
Chromium is one of the most versatile and widely
used alloys. It is used as an alloying agent in steel and cast iron
and in nonferrous alloys of nickel, copper, aluminum, and cobalt. It
is also widely used in electroplating for appearance and wear, in
powder metallurgy, and to make x-ray targets, mirrors, and stainless
steel.
(b) Capabilities.
Chromium is hard, brittle,
corrosion
resistant, and can be welded, machined, and forged.
(c) Limitations.
Chromium is not resistant to hydrochloric
acid, nor can it be used in the pure state because of its brittleness
and difficulty to work.
(3) Cobalt. The chemical symbol for cobalt is Co, and the chief
ores of cobalt are cobaltite and smaltite.
(a) Uses.
Cobalt is mainly used as an alloying element in
permanent and soft magnetic materials, high-speed tools bits and
cutters,
high-temperature
creep-resisting
alloys,
and
cemented
carbide tool bits and cutters.
It is also used in making insoluble
paint pigments and blue ceramic glazes.
(b) Capabilities.
Cobalt can be welded, limitedly machined,
and cold-drawn.
(c) Limitations.
Cobalt must be machined with cemented carbide
cutters.
(4) C o p p e r .
The chemical symbol
for copper
is Cu.
Most
copper produced today
comes from
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