Nimonic Alloy 90

Chemical Analysis
C Carbon
0.20 max
Mn Manganese
1.00 max
Si Silicon
1.00 max
Fe Iron
1.50 max
Cr Chromium
18.00 – 21.00
Co Cobalt
15.0 – 21.0
Al Aluminum
1.0 – 2.0
Ti Titanium
2.0 – 3.0
S Sulfur
0.015 max
Ni Nickel

General characteristics of Nimonic Alloy 90

This is a precipitation-hardenable nickel-chromium-cobalt alloy with strengthening additions of titanium and aluminum. The alloy has high stress-rupture strength and is creep resistant to 1690ºF(920ºC.)


Nimonic 90 alloy is used in extreme stress applications such as turbine blades, hot working tools, exhaust reheaters and high-temperature springs.


The alloy should be forged between 2100 and 1850ºF (1150 and 1010ºC) after which process it may be air cooled or water quenched, depending upon the size and intricacy of the forged part.

Heat treatment

For bar material the following heat treatment is recommended :

Solution treat at 1975ºF (1080ºC) for 8 hours and air cool or oil/water quench.

Precipitation treat at 1290ºF (700ºC) for 16hours and air cool.


The alloy should be in the fully heat-treated condition prior to machining operations. Machining should be carried out under strict conditions as specified by Special Metals Corporation, who should be consulted regarding detailed procedures.


Nimonic 90 alloy sheet may be welded by any resistance process. For material up to 5mm (0.2in.) thick, TIG or MIG processes are satisfactory. Above this thickness micro-cracking may occur in the weld and the heat-affected zone. Electron beam, friction, inertia and flash-butt welding are all satisfactory for material over 5 mm thick.

Welding should be done on solution-treated material and post-weld heat treatment is necessary to achieve optimum properties.

Further advice, if required, is available from Special Metals Corporation.


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