Alloy IN-738


Alloy IN-738

Alloy IN-738* is a vacuum melted, vacuum cast, precipitation hardenable nickel-base alloy possessing excellent high temperature creep-rupture strength combined with hot corrosion resistance superior to that of many high-strength superalloys of lower chromium content. It is designed to provide the gas turbine industry with an alloy which will have good creep strength up to 1800*F combined with the ability to withstand long-time exposure to the hot corrosive environments asso-ciated with the engine.

Alloy IN-738 exhibits tensile properties superior to and elevated temperature stress-rupture properties comparable to those of the widely used Alloy 713C along with substantially better sul-fidation resistance.

Two versions of Alloy IN-738 are produced: a high carbon version designated IN-738C and a low carbon version designated IN-738LC. The data reported in this bulletin were obtained primarily on high carbon (C) material. Where data are reported for the low carbon (LC) modification, they will be so indicated.

The greatest use for Alloy IN-738 is in the industrial gas turbine industry for engine parts required to withstand high temperature and stress combined with hot corrosion and sulfidation resistance. Applications of the alloy primarily are for gas turbine and jet engine components, such as blades, vanes and integral-wheels.

Chemical composition:

Element              Range                Nominal
Carbon             0.15-0.20                0.17
Cobalt              8.00-9.00                8.50
Chromium        15.70-16.30            16.00
Molybdenum      1.50-2.00               1.75
Tungsten           2.40-2.80               2.60
Tantalum           1.50-2.00               1.75
Columbium (Niobium) 0.60-1.10        0.90
Aluminum           3.20-3.70               3.40
Titanium             3.20-3.70               3.40
Aluminum + Titanium 6.50-7.20         6.80
Boron                0.005-0.015            0.010
Zirconium            0.05-0.15               0.10
Iron                     0.05 max              LAP†
Manganese           0.02 max              LAP
Silicon                  0.30 max              LAP
Sulfur                  0.015 max             LAP
Nickel                   Balance            Balance (61)


0.293 Ib/cu in. (8.11 g/cu cm)

Melting Range
2250-2400°F (1230-1315°C)

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