Inconel 903 Alloy

General Characteristics of Inconel 903 Alloy

This is a precipitation hardening high-temperature alloy with a low coefficient of thermal expansion and high strength at temperatures up to around 1200ºF (650ºC.) The alloy has high hot hardness and good thermal fatigue resistance.

Chemical Analysis
C Carbon
0.05 max
Mn Manganese
0.50 max
S and P Sulfur and Phosphorus
0.015 max
Si Silicon
0.50 max
Ni Nickel
38.0/40.0 x
Cr Chromium
0.50 max
Co Cobalt
Cu Copper
0.50 max
Al Aluminium
Ti Titanium
Cb + Ta Columbium + Tantalum
B Boron
0.008 max


The alloy finds use in casings, seals and other gas turbine engine components, hot-work die equipment such as extrusion dies, punches and mandrels and in high-pressure hydrogen environments. It finds use also in steam turbine blades, rocket thrust chambers and die casting dies.


Forging should be started at temperatures in the region of 2050ºF (1120ºC) and finished slightly below 1600ºF (870ºC.) Finish forging should be carried out at a temperature below 1700ºF (925ºC) and should involve a goodly reduction down to just below 1600ºF (870ºC.)
These low finishing temperatures provide a deformed grain structure, a requirement for stress-rupture ductility.

Heat treatment

Parts are treated at 1550/1600ºF (845/870ºC) for 1 hour and air cooled, with water or oil quenching suggested for large section sizes.
Aging is carried out at 1325ºF (720ºC) for 8 hrs followed by cooling at 100ºF/hr (56ºC/hr) to 1150ºF (620ºC) holding for 8 hrs and air cooling.


The alloy may be machined in either the solution-treated or age-hardened condition. Slow speeds and lots of power are required. Stock in the age-hardened condition yields a better surface finish.


The alloy may be readily welded by those processes used for precipitation-hardening materials. Welded areas and heat-affected zones may show relatively low 1200ºF (650ºC) tensile and stress rupture ductility.

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