Limiting Chemical Composition, %

Nia - 50.0-55.0
Cr - 17.0-21.0
Fe - Remainder
Nbb - 4.75-5.50
Mo - 2.80-3.30
Ti - 0.65-1.15
Al - 0.20-0.80
Coc - 1.0 max.
C - 0.08 max.
Mn - 0.35 max.
Si - 0.35 max.
P - 0.015 max.
S - 0.015 max.
B - 0.006 max.
Cu - 0.30 max.
aPlus Co.
bPlus Ta.
cIf determined.

Typical Mechanical Properties
(Precipitation Hardened)

Rupture Strength (1000 h)

Physical Constants and Thermal Properties

Density, Ib/in3 •••••• 0.296
g/cm3 •••••• 8.19
Melting Range, °F •••••• 2300 – 2437
°C •••••• 1260 – 1336
Specific Heat, Btu/lb •°F •••••• 0.104
J/kg • °C •••••• 435
Curie Temperature, °F •••••• -170
°C •••••• -112
Permeability at 200 Oersted (15.9 kA/m) •••••• 1.0011
Coefficient of Expansion,
70 – 200°F, 10-6 in/in • °F •••••• 7.2
21 – 93°C, μm/m • °C •••••• 13.0
Thermal Conductivity, Btu • in/ft2•h•°F •••••• 79
W/m• °C•••••• 11.4
Electrical Resistivity, ohm• circ mil/ft •••••• 751
μΩ•m •••••• 1.25

Specifications and Designation

UNS N07718
ASTM B 637, B 670
ASME Boiler Code Sections I, III
SAE AMS 5589, 5590, 5596,
5597, 5662-5664, 5832
Werkstoff Nr. 2.4668
WL Nr. 2.4668
MIL-N-24469
NACE MR-01-75
AECMA Pr EN 2404, 2405, 2407, 2408,
2952, 2961, 3219
AFNOR NC 19 Fe Nb

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