# Nimonic 90: Properties and Applications in High-Temperature Environments
## Introduction to Nimonic 90
Nimonic 90 is a nickel-chromium-cobalt alloy that belongs to the family of superalloys. Developed in the mid-20th century, this material has become a cornerstone in industries requiring materials that can withstand extreme temperatures while maintaining structural integrity.
## Chemical Composition
The unique properties of Nimonic 90 stem from its carefully balanced chemical composition:
– Nickel (Ni): ~55-60%
– Chromium (Cr): ~18-21%
Keyword: nimonic 90
– Cobalt (Co): ~15-21%
– Titanium (Ti): ~2-3%
– Aluminum (Al): ~1-2%
– Carbon (C): ≤0.13%
– Iron (Fe): ≤2%
– Manganese (Mn): ≤1%
– Silicon (Si): ≤1%
## Key Properties
### High-Temperature Strength
Nimonic 90 maintains excellent mechanical properties at temperatures up to 815°C (1500°F). Its yield strength and creep resistance make it ideal for applications where other materials would fail.
### Oxidation Resistance
The chromium content provides outstanding oxidation resistance, forming a protective oxide layer that prevents further degradation at high temperatures.
### Corrosion Resistance
Nimonic 90 exhibits good resistance to various forms of corrosion, including:
– Sulfidation
– Carburization
– Nitridation
– Chloride-induced stress corrosion cracking
### Thermal Stability
The alloy maintains dimensional stability under thermal cycling conditions, making it suitable for components that experience frequent temperature changes.
## Mechanical Properties
Property | Value
Tensile Strength (Room Temp) | 1000-1200 MPa
Yield Strength (Room Temp) | 700-900 MPa
Elongation | 15-25%
Hardness (Rockwell C) | 30-40
## Heat Treatment
Nimonic 90 typically undergoes the following heat treatment process:
1. Solution treatment at 1080°C (1975°F) for 8 hours, followed by air cooling
2. Aging at 700°C (1290°F) for 16 hours, followed by air cooling
This treatment optimizes the alloy’s mechanical properties and microstructure.
## Applications
### Aerospace Industry
Nimonic 90 is widely used in gas turbine engines for:
– Turbine blades
– Combustion chambers
– Afterburner components
– Exhaust systems
### Power Generation
In power plants, the alloy finds application in:
– Gas turbine components
– Steam turbine blades
– High-temperature fasteners
– Heat exchangers
### Industrial Processing
Other industrial applications include:
– Furnace components
– Heat treatment fixtures
– Chemical processing equipment
– Nuclear reactor components
## Fabrication and Machining
Working with Nimonic 90 requires special considerations:
### Machining
The alloy is difficult to machine due to its high strength and work hardening tendency. Recommended practices include:
– Using carbide tools
– Maintaining sharp cutting edges
– Applying generous coolant flow
– Using slow speeds and heavy feeds
### Welding
Nimonic 90 can be welded using:
– Gas tungsten arc welding (GTAW)
– Electron beam welding
– Resistance welding
Post-weld heat treatment is typically required to restore properties.
## Comparison with Other Superalloys
While similar to Inconel 718 and Waspaloy, Nimonic 90 offers:
– Better creep resistance than Inconel 718 at temperatures above 650°C
– Superior oxidation resistance compared to Waspaloy
– More cost-effective for certain applications
## Future Developments
Research continues to enhance Nimonic 90’s capabilities through:
– Improved heat treatment processes
– Surface modification techniques
– Composite material development
– Additive manufacturing applications
## Conclusion
Nimonic 90 remains a critical material
