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NIMONIC Alloy 263 UNS N07263: Properties and Applications

Introduction

NIMONIC Alloy 263 (UNS N07263) is a nickel-chromium-cobalt alloy known for its exceptional high-temperature strength and corrosion resistance. Developed for demanding aerospace and industrial applications, this alloy combines excellent mechanical properties with weldability and fabricability, making it a preferred choice for critical components.

Chemical Composition

The chemical composition of NIMONIC Alloy 263 is carefully balanced to optimize its performance:

• Nickel (Ni): 51% (primary base element)
• Chromium (Cr): 20% (provides oxidation resistance)
• Cobalt (Co): 20% (enhances high-temperature strength)
• Molybdenum (Mo): 5.9% (improves creep resistance)
• Titanium (Ti): 2.2% (contributes to precipitation hardening)
• Aluminum (Al): 0.6% (works with Ti for strengthening)
• Carbon (C): 0.06% max
• Iron (Fe): 0.7% max

Key Properties

NIMONIC Alloy 263 offers a unique combination of properties that make it suitable for extreme environments:

Mechanical Properties

At room temperature:

• Tensile Strength: 950-1200 MPa
• Yield Strength: 550-750 MPa
• Elongation: 30-40%

At elevated temperatures (700°C/1292°F):

• Retains approximately 70% of room temperature strength
• Excellent creep resistance

Physical Properties

• Density: 8.36 g/cm³
• Melting Range: 1330-1360°C (2426-2480°F)
• Thermal Conductivity: 11.2 W/m·K at 20°C
• Electrical Resistivity: 1.25 μΩ·m at 20°C

Corrosion Resistance

NIMONIC Alloy 263 demonstrates excellent resistance to:

• Oxidation at high temperatures
• Carburization and nitridation
• Stress corrosion cracking

Heat Treatment

The alloy typically undergoes a two-stage heat treatment process:

1. Solution Treatment: 1150°C (2100°F) followed by rapid cooling
2. Aging: 800°C (1470°F) for 8 hours, air cooling

This treatment optimizes the precipitation of gamma prime phase (Ni3(Al,Ti)) for maximum strength.

Fabrication and Welding</h2