# Alloy 907 UNS N19907: Properties and Applications

## Introduction to Alloy 907 UNS N19907

Alloy 907, also known as UNS N19907, is a nickel-iron-based superalloy designed for high-temperature applications. This alloy exhibits excellent mechanical properties and resistance to thermal expansion, making it a popular choice in industries requiring materials that can withstand extreme conditions.

## Chemical Composition

The unique properties of Alloy 907 stem from its carefully balanced chemical composition:

– Nickel (Ni): 38-45%
– Iron (Fe): Balance
– Cobalt (Co): 12-16%
– Niobium (Nb): 4.5-5.5%
– Titanium (Ti): 1.3-1.8%
– Aluminum (Al): 0.7-1.2%
– Silicon (Si): ≤0.5%
– Manganese (Mn): ≤0.5%
– Carbon (C): ≤0.06%

## Mechanical Properties

Alloy 907 offers an impressive combination of mechanical properties:

– Tensile Strength: 1100-1300 MPa (160-190 ksi)
– Yield Strength: 800-1000 MPa (116-145 ksi)
– Elongation: 10-20%
– Hardness: 30-40 HRC
– Fatigue Strength: Excellent at elevated temperatures

## Physical Properties

The physical characteristics of Alloy 907 include:

– Density: 8.22 g/cm³ (0.297 lb/in³)
– Melting Range: 1315-1365°C (2400-2490°F)
– Thermal Expansion Coefficient: 11.5 × 10⁻⁶/°C (20-100°C)
– Thermal Conductivity: 11.7 W/m·K (at 100°C)
– Electrical Resistivity: 1.15 μΩ·m

## Key Features and Advantages

Alloy 907 stands out due to several important characteristics:

– Excellent high-temperature strength and creep resistance
– Good oxidation resistance up to 815°C (1500°F)
– Low thermal expansion coefficient
– Superior fatigue resistance
– Good weldability and fabricability
– Resistance to thermal shock

## Common Applications

Due to its unique properties, Alloy 907 finds use in various demanding applications:

### Aerospace Industry

– Jet engine components
– Turbine blades and disks
– Afterburner parts
– High-temperature fasteners

### Power Generation

– Gas turbine components
– Steam turbine parts
– Nuclear reactor components
– Heat exchangers

### Industrial Applications

– High-temperature fasteners
– Pressure vessels
– Chemical processing equipment
– Oil and gas components

## Heat Treatment

Proper heat treatment is crucial for optimizing Alloy 907’s properties:

– Solution Annealing: 980-1010°C (1800-1850°F), followed by rapid cooling
– Aging Treatment: 720-760°C (1325-1400°F) for 8-16 hours, air cooling

## Fabrication and Machining

While Alloy 907 can be challenging to machine, following proper techniques yields good results:

– Use rigid machine setups and sharp tools
– Employ positive rake angles
– Maintain adequate coolant flow
– Consider using carbide or ceramic cutting tools
– Annealed condition is preferred for machining operations

## Corrosion Resistance

Alloy 907 offers good resistance to:

– Oxidation at high temperatures
– Carburization
– Sulfidation
– Chloride stress corrosion cracking

However, it’s not recommended for highly reducing environments or strong acids.

## Comparison with Similar Alloys

Alloy 907 compares favorably with other high-temperature alloys:

– Better thermal expansion characteristics than Inconel 718
– Superior creep resistance compared to Waspaloy
– Higher strength