NIMONIC Alloy 263 UNS N07263: Properties and Applications

# NIMONIC Alloy 263 UNS N07263: Properties and Applications

## Introduction to NIMONIC Alloy 263

NIMONIC Alloy 263, also known by its UNS designation N07263, is a nickel-chromium-cobalt alloy that offers a unique combination of high-temperature strength, oxidation resistance, and fabricability. This alloy is part of the renowned NIMONIC series, which has been widely used in aerospace and industrial applications for decades.

## Chemical Composition

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

– Nickel (Ni): 51% (base)
– Chromium (Cr): 20%
– Cobalt (Co): 20%
– Molybdenum (Mo): 5.9%
– Titanium (Ti): 2.1%
– Aluminum (Al): 0.4%
– Carbon (C): 0.04-0.08%
– Boron (B): 0.005%
– Iron (Fe): ≤0.7%
– Manganese (Mn): ≤0.6%
– Silicon (Si): ≤0.4%

## Mechanical Properties

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

### Room Temperature Properties

– Tensile Strength: 950-1200 MPa
– Yield Strength (0.2% offset): 550-750 MPa
– Elongation: 20-30%
– Hardness: 250-320 HB

### Elevated Temperature Properties

At 700°C (1292°F):

– Tensile Strength: ~650 MPa
– Creep Strength (1000h rupture): ~200 MPa

## Physical Properties

The physical characteristics of NIMONIC Alloy 263 include:

– Density: 8.36 g/cm³
– Melting Range: 1315-1365°C (2400-2490°F)
– Thermal Expansion Coefficient: 13.5 μm/m°C (20-100°C)
– Thermal Conductivity: 11.7 W/m·K (20°C)
– Electrical Resistivity: 1.18 μΩ·m (20°C)

## Key Features and Advantages

NIMONIC Alloy 263 offers several distinct advantages:

– Excellent high-temperature strength and creep resistance
– Good oxidation resistance up to 1000°C (1832°F)
– Superior thermal fatigue resistance
– Good fabricability and weldability compared to other high-temperature alloys
– Resistance to carburization and nitridation
– Stable microstructure at elevated temperatures

## Applications of NIMONIC Alloy 263

Due to its exceptional properties, NIMONIC Alloy 263 finds applications in various demanding industries:

### Aerospace Industry

– Combustion chambers and liners
– Afterburner components
– Exhaust systems
– Turbine casings

### Power Generation

– Gas turbine components
– Combustor cans
– Transition ducts
– Heat exchangers

### Industrial Applications

– High-temperature fasteners
– Furnace components
– Chemical processing equipment
– Nuclear reactor components

## Fabrication and Processing

NIMONIC Alloy 263 can be processed using standard techniques:

### Forming

– Hot working: 1050-1200°C (1922-2192°F)
– Cold working: Possible with intermediate annealing

### Heat Treatment

– Solution treatment: 1150°C (2102°F) followed by rapid cooling
– Aging: 800°C (1472°F) for 8 hours (optional for some applications)

### Welding

– Recommended methods: TIG, MIG, and resistance welding
– Post-weld heat treatment often required

## Comparison with Similar Alloys

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