# 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 applications requiring exceptional performance at elevated temperatures. Its unique composition and mechanical properties make it indispensable in industries where conventional materials would fail under extreme thermal and mechanical stress.
## Chemical Composition and Microstructure
The chemical composition of Nimonic 90 plays a crucial role in its high-temperature capabilities:
– Nickel (Ni): 55-60% (base element)
– Chromium (Cr): 18-21%
– Cobalt (Co): 15-21%
– Titanium (Ti): 2.0-3.0%
– Aluminum (Al): 1.0-2.0%
– Iron (Fe): ≤2.0%
– Carbon (C): ≤0.13%
– Manganese (Mn): ≤1.0%
– Silicon (Si): ≤1.0%
The alloy’s microstructure consists of a gamma (γ) matrix with gamma prime (γ’) precipitates, which contribute significantly to its strength at high temperatures through precipitation hardening.
## Mechanical Properties
Nimonic 90 exhibits remarkable mechanical properties that make it suitable for demanding applications:
### Room Temperature Properties
– Tensile Strength: 900-1100 MPa
– Yield Strength: 600-750 MPa
– Elongation: 20-30%
– Hardness: 250-300 HB
### Elevated Temperature Properties (700-800°C)
– Tensile Strength: 600-800 MPa
– Creep Resistance: Excellent
– Fatigue Strength: Superior to most conventional alloys
## Thermal Properties
The thermal characteristics of Nimonic 90 contribute to its performance in high-temperature environments:
– Melting Range: 1320-1365°C
– Continuous Service Temperature: Up to 920°C
– Thermal Expansion Coefficient: 13.5 × 10⁻⁶/°C (20-1000°C)
– Thermal Conductivity: 11.2 W/m·K at 20°C
Keyword: nimonic 90
## Key Advantages
Nimonic 90 offers several distinct advantages over other high-temperature materials:
– Exceptional creep resistance under stress at elevated temperatures
– Outstanding oxidation and corrosion resistance
– Good fabricability and weldability compared to other superalloys
– Excellent fatigue resistance in cyclic loading conditions
– Stable microstructure at high operating temperatures
## Manufacturing and Processing
The production and processing of Nimonic 90 require specialized techniques:
### Forming Processes
– Hot working: Preferred method for shaping at 1050-1150°C
– Cold working: Possible but requires intermediate annealing
– Machining: Challenging due to work hardening; requires rigid setups
### Heat Treatment
– Solution treatment: Typically at 1080°C followed by rapid cooling
– Aging: Performed at 700-800°C to optimize γ’ precipitation
### Joining Methods
– Gas tungsten arc welding (GTAW) with matching filler metal
– Resistance welding for thin sections
– Brazing using nickel-based filler alloys
## Applications in High-Temperature Environments
Nimonic 90 finds extensive use in various industries where high-temperature performance is critical:
### Aerospace Industry
– Turbine blades and vanes in gas turbine engines
– Combustion chamber components
– Afterburner parts
– Exhaust systems
### Power Generation
– Gas turbine components
– Steam turbine blades
– Nuclear reactor components
– Heat exchangers in power plants
### Industrial Applications
– High-temperature fasteners and bolts
– Furnace components
– Chemical processing equipment
– Glass manufacturing tools
## Comparison with Other Superalloys
When compared to similar materials, Nimonic 90 offers a
