Product Description
A nickel-chromium-cobalt superalloy age hardened by the precipitation of a gamma prime second phase. Alloy 740H exhibits excellent high temperature strength in the age-hardened condition up to 1500°F (815°C). With its high contents of chromium and cobalt, alloy 740H offers excellent resistance to oxidation, carburization and sulfidation at elevated temperatures. Alloy 740H is targeted for use as advanced power production boiler tubes.
STANDARD PRODUCT FORMS
Bar, seamless tubes.
MAJOR SPECIFICATIONS
Contact Special Metals
LIMITING CHEMICAL COMPOSITION, %
Nominal
C..................... 0.03
Ni............. Balance
Cr.................... 25.0
Mo.....................0.5
Co................... 20.0
Al.......................1.0
Ti.......................1.8
Nb.....................2.0
Mn.................. 0.30
Fe......................0.7
Si.......................0.5
C..................... 0.03
Ni............. Balance
Cr.................... 25.0
Mo.....................0.5
Co................... 20.0
Al.......................1.0
Ti.......................1.8
Nb.....................2.0
Mn.................. 0.30
Fe......................0.7
Si.......................0.5
PHYSICAL CONSTANTS AND THERMAL PROPERTIES
Density, Ib/in3..........................................................................0.291
g/cm3......................................................................... 8.05
Melting Point, °F......................................................2350 – 2484
°C......................................................1288 – 1362
Specific Heat, Btu/lb •°F.....................................................0.108
J/kg •°C........................................................... 449
Electrical Resistivity, ohm • circ mil/ft...........................702.7
μΩ•m...............................................1.168
Thermal Conductivity, Btu • in/ft2• h•°F........................... 72.9
W/m•°C........................................... 10.2
Coefficient of Expansion, 10-6 in/in•°F (μm/m•°C)
70-200°F (21–93°C)...................6.84 (12.38)
Young’s ModulusA, 103 psi........................................................32
GPa........................................................... 221
Shear’s ModulusA, 103 psi..................................................... 11.5
GPa...............................................................79
Poisson’s RatioA....................................................................... 0.35
Magnetic Permeability..................................................... <1.005
ARoom temperature, as aged.
g/cm3......................................................................... 8.05
Melting Point, °F......................................................2350 – 2484
°C......................................................1288 – 1362
Specific Heat, Btu/lb •°F.....................................................0.108
J/kg •°C........................................................... 449
Electrical Resistivity, ohm • circ mil/ft...........................702.7
μΩ•m...............................................1.168
Thermal Conductivity, Btu • in/ft2• h•°F........................... 72.9
W/m•°C........................................... 10.2
Coefficient of Expansion, 10-6 in/in•°F (μm/m•°C)
70-200°F (21–93°C)...................6.84 (12.38)
Young’s ModulusA, 103 psi........................................................32
GPa........................................................... 221
Shear’s ModulusA, 103 psi..................................................... 11.5
GPa...............................................................79
Poisson’s RatioA....................................................................... 0.35
Magnetic Permeability..................................................... <1.005
ARoom temperature, as aged.
TYPICAL MECHANICAL PROPERTIES

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