Tungsten has about the same electrical conductivity and resistivity, coefficient of thermal expansion, and about the same resistance to corrosion by mineral acids as molybdenum. Tungsten is high strength at temperatures above 2,000°F, but because the melting point is higher, it retains significant strength at higher temperatures. The elastic modulus for tungsten is about 25% higher than that of molybdenum, and its density is almost twice that of molybdenum. All commercial unalloyed tungsten is produced by powder-metallurgy methods; it is available as rod, wire, plate, sheet, and some forged shapes. For some special applications, vacuum-arc-melted tungsten can be produced, but it is expensive and limited to relatively small sections.
Several tungsten alloys are produced by liquid-phase sintering of compacts of tungsten powder with binders of nickel-copper, iron-nickel, iron-copper, or nickel-cobalt-molybdenum combinations; tungsten usually comprises 85 to 95% of the alloy by weight. These alloys are often identified as heavy metals or machinable tungsten alloys. In compact forms, the alloys can be machined by turning, drilling, boring, milling, and shaping; they are not available in mill product forms because they are unable to be wrought at any temperature.
Applications
Typical Applications include weights and counterbalances for aircraft control surfaces and rotor blades, guidance platforms, counterbalances for fly wheels, turbines and engine crankshafts, vibration damping governors, filaments, and fuse masses. Other applications include radiation shielding, gyro rotors, weapons including armor piercing applications, and high temperature tooling.
Alloy Type
(%)
90 W
6 Ni 4 Cu
90 W
7 Ni 3 Fe
92.5 W
5.25 Ni 2.25 Fe
92.5 W
Balance Ni, Fe, Mo
93 W
Balance Ni, Fe, Mo
95 W
3.5 Ni 1.5 Cu
95 W
3.5 Ni 1.5 Fe
97 W
2.1 Ni .9 Fe
MIL-T-21014
Class 1
Class 1
Class 1
-
-
Class 3
Class 3
Class 4
SAE-AMS-T-21014
Class 1
Class 1
Class 2
-
-
Class 3
Class 3
Class 4
AMS 7725 C
7725 C
7725 C
--
--
--
--
--
--
ASTM B777-87
Class 1
Class 1
Class 2
-
-
Class 3
Class 3
Class 4
Typical Density
(g/cc)
17.1
17.1
17.5
17.6
17.7
18
18
18.5
Typical Density
(lbs/in3)
0.614
0.614
0.632
0.636
0.639
0.65
0.65
0.668
Typical Hardness RC
24
25
26
30
32
27
27
28
Ultimate Tensile Strength Min
(ksi)
110,000
120,000
114,000
120,000
125,000
110,000
120,000
123,000
0.2% Offset Yield Strength Min
(ksi)
80,000
88,000
84,000
90,000
95,000
85,000
90,000
85,000
Minimum % Elongation
(1" gage length)
6
10
7
4
4
7
7
5
Proportional Elastic Limit
(PSI)
45,000
52,000
46,000
55,000
60,000
45,000
44,000
45,000
Modulus of Elasticity
(x106psi)
40 x 106
45 x 106
47 x 106
52 x 106
53 x 106
45 x 106
50 x 106
53 x 106
Coefficient of Thermal Expansion x10-6/0C
(20-400C)
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