with an inert gas atmosphere has proven most
Both commercially pure and alloy titanium can
absorb large amounts of cold-work without cracking.
Practically anything that can be deep drawn in
low-carbon steel can be duplicated in commercially
pure titanium, although the titanium may require more
IDENTIFICATION OF TITANIUM.Titanium
metal, pure or alloyed, is easily identified. When
touched with a grinding wheel, it makes white spark
traces that end in brilliant white bursts. When rubbed
with a piece of glass, moistened titanium will leave a
dark line similar in appearance to a pencil mark.
Copper and Copper Alloys
Most commercial copper is refined to a purity of
99.9 percent minimum copper plus silver. It is the only
reddish-colored metal, and it is second only to silver in
electrical conductivity. Its use as a structural material is
limited because of its great weight. However, some of
its outstanding characteristics, such as its high electrical
and heat conductivity, in many cases overbalance the
Because it is very malleable and ductile, copper is
ideal for making wire. In aircraft, copper is used
primarily for the electrical system and for instrument
tubing and bonding. It is corroded by salt water, but is
not affected by fresh water. The ultimate tensile strength
of copper varies greatly. For cast copper, the tensile
strength is about 25,000 psi; and when cold-rolled or
cold-drawn, its tensile strength increases, ranging from
40,000 to 67,000 psi.
BRASS.Brass is a copper alloy containing zinc
and small amounts of aluminum, iron, lead, manganese,
magnesium, nickel, phosphorous, and tin. Brass with a
zinc content of 30 to 35 percent is very ductile, while
that containing 45 percent has relatively high strength.
Muntz metal is a brass composed of 60 percent copper
and 40 percent zinc. It has excellent corrosion-resistant
qualities when in contact with saltwater. Its strength can
be increased by heat treatment. As cast, this metal has
an ultimate tensile strength of 50,000 psi and can be
elongated 18 percent. It is used in making bolts and nuts,
as well as parts that come in contact with salt water.
Red brass, sometimes termed bronze because of its tin
content, is used in fuel and oil line fittings. This metal
has good casting and finishing properties and machines
BRONZES.Bronzes are copper alloys containing
tin. The true bronzes have up to 25 percent tin, but those
below 11 percent are most useful, especially for such
items as tube fittings in aircraft.
Among the copper alloys are the copper aluminum
alloys, of which the aluminum bronzes rank very high
in aircraft usage. They would find greater usefulness in
structures if it were not for their strength/weight ratio as
compared with alloy steels. Wrought aluminum bronzes
are almost as strong and ductile as medium-carbon steel,
and possess a high degree of resistance to corrosion by
air, salt water, and chemicals. They are readily forged,
hot- or cold-rolled, and some react to heat treatment.
These copper-based alloys contain up to 16 percent
of aluminum (usually 5 to 11 percent) to which other
metals such as iron, nickel, or manganese maybe added.
Aluminum bronzes have good tearing qualities, great
strength, hardness, and resistance to both shock and
fatigue. Because of these properties, they are used for
diaphragms and gears, air pumps, condenser bolts, and
slide liners. Aluminum bronzes are available in rods,
bars, plates, sheets, strips, and forgings.
Cast aluminum bronzes, using about 89 percent
copper, 9 percent aluminum, and 2 percent of other
elements, have high strength combined with ductility,
and are resistant to corrosion, shock, and fatigue.
Because of these properties, cast aluminum bronze is
used in gun mounts, bearings, and pump parts. These
alloys are useful in areas exposed to salt water and
Manganese bronze is an exceptionally high-
strength, tough, corrosion-resistant copper zinc alloy
containing aluminum, manganese, iron, and
occasionally nickel or tin. This metal can be formed,
extruded, drawn, or rolled to any desired shape. In rod
form, it is generally used for machined parts. Otherwise
it is used in catapults, landing gears, and brackets.
Silicon bronze is composed of about 95 percent
copper, 3 percent silicon, and 2 percent mixture of
manganese, zinc, iron, tin, and aluminum. Although not
a bronze in the true sense of the word because of its small
tin content, silicon bronze has high strength and great
corrosion resistance and is used variably.
BERYLLIUM COPPER.Beryllium copper is
one of the most successful of all the copper-based alloys.
It is a recently developed alloy containing about 97
percent copper, 2 percent beryllium, and sufficient
nickel to increase the percentage of elongation. The
most valuable feature of this metal is that the physical
properties can be greatly stepped up by heat