# NIMONIC Alloy 263 UNS N07263: Properties and Applications

## Introduction to NIMONIC Alloy 263

NIMONIC Alloy 263 (UNS N07263) is a nickel-chromium-cobalt superalloy known for its excellent high-temperature strength and oxidation resistance. Developed by Rolls-Royce in the 1960s, this alloy has become a preferred material for demanding aerospace and industrial applications.

## Chemical Composition

The chemical composition of NIMONIC Alloy 263 plays a crucial role in its performance characteristics:

– Nickel (Ni): 50-55%

– Chromium (Cr): 19-21%
– Cobalt (Co): 19-21%
– Molybdenum (Mo): 5.6-6.1%
– Titanium (Ti): 1.9-2.4%
– Aluminum (Al): 0.3-0.6%
– Carbon (C): ≤0.08%
– Boron (B): ≤0.005%
– Iron (Fe): ≤0.7%

## Mechanical Properties

NIMONIC Alloy 263 exhibits impressive mechanical properties across a wide temperature range:

– Tensile Strength: 950-1200 MPa at room temperature
– Yield Strength: 550-850 MPa at room temperature
– Elongation: 20-30% at room temperature
– Creep Resistance: Excellent performance up to 850°C (1562°F)
– Fatigue Resistance: Superior high-cycle fatigue properties

## Physical Properties

The physical characteristics of this alloy include:

– Density: 8.36 g/cm³
– Melting Range: 1290-1350°C (2354-2462°F)
– Thermal Conductivity: 11.2 W/m·K at 20°C
– Electrical Resistivity: 1.18 μΩ·m at 20°C
– Coefficient of Thermal Expansion: 13.5 μm/m·K (20-100°C)

## Heat Treatment

Proper heat treatment is essential for optimizing the properties of NIMONIC Alloy 263:

– Solution Treatment: 1150°C (2102°F) for 2 hours, followed by air cooling
– Aging Treatment: 800°C (1472°F) for 8 hours, followed by air cooling
– Stress Relieving: 700-750°C (1292-1382°F) for 4 hours

## Key Advantages

NIMONIC Alloy 263 offers several significant advantages:

– Exceptional high-temperature strength
– Outstanding oxidation resistance up to 1000°C (1832°F)
– Good resistance to thermal fatigue
– Excellent fabricability and weldability
– Superior creep-rupture properties
– Good corrosion resistance in various environments

## Applications

Due to its unique combination of properties, NIMONIC Alloy 263 finds applications in several demanding industries:

### Aerospace Industry

– Gas turbine engine components
– Combustion chambers
– Afterburner components
– Exhaust systems
– Turbine casings

### Power Generation

– Gas turbine components
– Heat exchangers
– High-temperature fasteners
– Steam turbine parts

### Industrial Applications

– Chemical processing equipment
– Heat treatment fixtures
– Nuclear reactor components
– High-temperature springs

## Fabrication and Machining

Working with NIMONIC Alloy 263 requires special considerations:

– Machining: Requires rigid setups, sharp tools, and proper cooling
– Welding: Can be welded using TIG, MIG, and resistance welding methods
– Forming: Hot forming is preferred above 1000°C (1832°F)
– Forging: Performed in the temperature range of 1050-1150°C (1922-