treatment. K-Monel has been successfully used for
occasionally nickel or tin. This metal can be formed,
gears, chains, and structural members in aircraft that
extruded, drawn, or rolled to any desired shape. In rod
are subjected to corrosive attacks. This alloy is
form, it is generally used for machined parts. Otherwise
nonmagnetic at all temperatures. K-Monel can be
it is used in catapults, landing gears, and brackets.
successfully welded.
Silicon bronze is composed of about 95 percent
copper, 3 percent silicon, and 2 percent mixture of
Magnesium and Magnesium Alloys
manganese, zinc, iron, tin, and aluminum. Although not
a bronze in the true sense of the word because of its
Magnesium, the world's lightest structural metal, is
small tin content, silicon bronze has high strength and
a silvery-white material weighing only two-thirds as
great corrosion resistance and is used variably.
much as aluminum. Magnesium does not possess
sufficient strength in its pure state for structural uses;
BERYLLIUM COPPER.--Beryllium copper is
but when it is alloyed with zinc, aluminum, and
one of the most successful of all the copper-based
manganese, it produces an alloy having the highest
alloys. It is a recently developed alloy containing about
strength/weight ratio.
97 percent copper, 2 percent beryllium, and sufficient
nickel to increase the percentage of elongation. The
Magnesium is probably more widely distributed in
most valuable feature of this metal is that the physical
nature than any other metal. It can be obtained from
properties can be greatly stepped up by heat
such ores as dolomite and magnesite, from
treatmentthe tensile strength rising from 70,000 psi in
underground brines, from waste liquors of potash, and
the annealed state to 200,000 psi in the heat-treated
from seawater. With about 10 million pounds of
state. The resistance of beryllium copper to fatigue and
magnesium in 1 cubic mile of seawater, there is no
wear makes it suitable for diaphragms, precision
danger of a dwindling supply.
bearings and bushings, ball cages, spring washers, and
Magnesium is used extensively in the manufacture
nonsparking tools.
of helicopters. Its low resistance to corrosion has been a
factor in reducing its use in conventional aircraft.
Monel
The machining characteristics of magnesium
Monel, the leading high-nickel alloy, combines the
alloys are excellent. Usually the maximum speeds of
properties of high strength and excellent corrosion
machine tools can be used with heavy cuts and high
resistance. This metal consists of 67 percent nickel, 30
feed rates. Power requirements for magnesium alloys
percent copper, 1.4 percent iron, 1 percent manganese,
are about one-sixth of those for mild steel. An excellent
and 0.15 percent carbon. It cannot be hardened by heat
surface finish can be produced, and, in most cases,
treatment; it responds only to cold-working.
grinding is not essential. Standard machine operations
can be performed to tolerances of a few ten-thousandths
Monel, adaptable to castings and hot- or
of an inch. There is no tendency of the metal to tear or
cold-working, can be successfully welded and has
drag.
working properties similar to those of steel. It has a
tensile strength of 65,000 psi that, by means of
Magnesium alloy sheets can be worked in much the
cold-working, may be increased to 160,000 psi, thus
same manner as other sheet metal with one exception
entitling this metal to classification among the tough
the metal must be worked while hot. The structure of
magnesium is such that the alloys work harden rapidly
chains, for operating retractable landing gears, and for
at room temperatures. The work is usually done at
structural parts subject to corrosion. In aircraft, Monel
temperatures ranging from 450F to 650F, which is a
has long been used for parts demanding both strength
disadvantage. However, compensations are offered by
and high resistance to corrosion, such as exhaust
the fact that in the ranges used, magnesium is more
manifolds and carburetor needle valves and sleeves.
easily formed than other materials. Sheets can be
sheared in much the same way as other metals, except
K-Monel
that a rough flaky fracture is produced on sheets thicker
than about 0.064 inch. A better edge will result on a
K-Monel is a nonferrous alloy containing mainly
sheet over 0.064 inch thick if it is sheared hot.
nickel, copper, and aluminum. It is produced by adding
a small amount of aluminum to the Monel formula. It is
Annealed sheet can be heated to 600F, but
corrosion resistant and capable of hardening by heat
hard-rolled sheet should not be heated above 275F. A
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