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Invar Alloy

Invar Alloy

Invar, otherwise known as FeNi36 (64FeNi in the US), is a nickel-iron alloy known for its consistent thermal expansion coefficient (α or CTE). Its name, Invar, signifies its resistance to temperature-induced fluctuations.

Equivalent grades

• Invar Alloy
• UNS k93600
• ASTM F1684
• FeNi36
• Invar 36

Chemical Composition Reference


Physical Property Reference

• Density: 8.05 g/cm³

• Youngs Modulus: 141 GPa

• Yield Strength: 483 MPa

• Thermal Conducitivity: 10.4 W/K·m

• Specific Heat: 0.515 J/g-°C

Stock & Dimensions

Our warehouse has a large number of stock to provide you with a variety of products in different sizes, and can also customize the size according to your needs.
• Bar: 0.5~600mm Diameter
• Coil: 0.5~150mm Thick
• Plate: 0.5~200mm Thick
• Pipe: 6~630mm External Diameter; 0.5~40mm Wall Tick
• Available in specific sizes

Product Forms

We provide you with a variety of product forms, including but not limited to:
• Bar/Rod
• Pipe/Tube
• Coil/Strip
• Plate/Sheet/Circle
• Wire
• Fitting (Flange, Elbow, Tee...)
• Customize

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Invar Alloy

Essential details
Like other nickel/iron compositions, Invar is a solid solution; that is, it is a single-phase alloy. In one commercial version it consists of approximately 36% nickel and 64% iron. Common grades of Invar have a coefficient of thermal expansion (denoted α, and measured between 20 °C and 100 °C) of about 1.2 × 10−6 K−1 (1.2 ppm/°C), while ordinary steels have values of around 11–15 ppm/°C. Extra-pure grades (<0.1% Co) can readily produce values as low as 0.62–0.65 ppm/°C. Some formulations display negative thermal expansion (NTE) characteristics. Though it displays high dimensional stability over a range of temperatures, it does have a propensity to creep.


- Composite molds for the aerospace industry

- Bimetal thermostats

- Clock balance wheels

- Containers and transfer lines for LNG tankers

- Echo boxes and filters for mobile telephones

- Electrical circuit breakers & transformers

- Electron gun components

- High voltage transmission lines

- Laser components

- Magnetic shielding

- Radar and microwave cavity resonators

- Scientific instruments

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