Copper becomes hard when worked but can be
has the general working characteristics of copper but
must be worked cold.
softened easily if you heat it cherry red and then cool
it. Its strength, however, decreases rapidly at
These and the many other copper alloys
temperatures above 400F.
commonly used by the Navy have certain physical
and mechanical properties (imparted by the various
Pure copper is normally used in molded or shaped
alloying elements) that cause one alloy to be more
forms when machining is not required. Copper for
effective than another for a given application.
normal shipboard use generally is alloyed with an
Remember this if you go to the metal storage rack and
element that provides good machinability.
select a bronze-looking metal without regard to the
Brass. --Brass is an alloy of copper and zinc.
specific type. The part you make may fail
Complex brasses contain additional alloying agents,
prematurely in spite of the skill and attention to detail
such as aluminum, lead, iron, manganese, or
that you use to machine it.
phosphorus. Naval brass is a true brass containing
NICKEL ALLOYS.--Nickel is a hard, malleable,
about 60 percent copper, 39 percent zinc, and 1
and ductile metal. It is resistant to corrosion and
percent tin added for corrosion resistance. It is used
therefore often is used as a coating on other metals.
for propeller shafts, valve stems, and marine
Combined with other metals, it makes a tough strong
hardware.
alloy.
Brass used by the Navy is classified as either
Nickel-Copper.--Nickel-copper alloys are
leaded or unleaded, meaning that small amounts of
stronger and harder than either nickel or copper. They
lead may or may not be used in the copper-zinc
have high resistance to corrosion and are strong
mixture. Lead improves the machinability of brass.
enough to be substituted for steel when corrosion
Bronze. --Bronze is primarily an alloy of copper
resistance is of primary importance. Probably the
and tin, although several other alloying elements are
best known nickel-copper alloy is Monel. It contains
added to produce special bronze alloys. Aluminum,
approximately 65 percent nickel, 30 percent copper,
nickel, phosphorous, silicon, and manganese are the
and small percentages of iron, manganese, silicon,
most widely used alloying metals.
and cobalt. Monel is used for pump shafts and
internal parts, valve seats and stems, and many other
Gunmetal. --Gunmetal, a copper-tin alloy,
applications requiring both strength and corrosion
contains approximately 86-89 percent copper, 7 1/2-9
resistance.
percent tin, 3-5 percent zinc, 0.3 percent lead, 0.15
percent iron, 0.05 percent phosphorous, and 1 percent
K-Monel.--K-Monel is essentially the same as
nickel. As you can see by the rather complex analysis
Monel except it contains about 3 percent aluminum
of this bronze alloy, the term copper-tin is used only
and is harder and stronger than other grades of Monel.
to designate the major alloying elements. Gunmetal
K-Monel stock is very difficult to machine. You can
bronze is used for bearings, bushings, pump bodies,
improve the metal's machinability considerably by
valves, impellers, and gears.
annealing it immediately before machining. K-Monel
is used for the shaft sleeves on many pumps because
Aluminum Bronze. --Aluminum bronze is
of its resistance to the heating and rubbing action of
actually a copper-aluminum alloy that does not
the packing.
contain any tin. It is made of 86 percent copper, 8
1/2-9 percent aluminum, 2 1/2-4 percent iron, and 1
There are several other nickel alloys that you may
percent of miscellaneous alloys. It is used for valve
find in Navy equipment. Inconel; Inconel-X; and H,
seats and stems, bearings, gears, propellers, and
S, R, and KR Monel are a few of the more common
marine hardware.
alloys.
Copper-Nickel.--Copper-nickel alloy is used
ALUMINUM ALLOYS.--Aluminum is being
extensively aboard ship because of its high resistance
used more and more in ship construction because of
to saltwater corrosion. It is used in piping and tubing.
light weight, easy workability, and good appearance.
In sheet form it is used to construct small storage
Pure aluminum is soft and not very strong. When
tanks and hot water reservoirs. Copper-nickel alloy
alloying elements such as magnesium, copper, nickel,
and silicon are added, however, a much stronger metal
may contain either 70 percent copper and 30 percent
nickel or 90 percent copper and 10 percent nickel. It
is produced.
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