Alloy 36 (Invar®) Strip (UNS K93600)

Alloy 36 (Invar®) is a nickel-iron alloy containing approximately 36% nickel and balance iron. It is known for its exceptionally low coefficient of thermal expansion up to 400°F (204°C), making it an ideal material for precision components, glass-to-metal sealing applications, and electronic assemblies requiring dimensional stability. We manufacture Alloy 36 strip and wire to ASTM F30 requirements for demanding electronic and industrial applications.

Why Is Alloy 36 Used for Controlled Thermal Expansion?

Alloy 36 minimizes dimensional changes caused by temperature fluctuations. It’s extremely low thermal expansion helps prevent stress between dissimilar materials, supporting long-term reliability in hermetic sealing, instrumentation, and precision electronic applications.

What Is the Chemical Composition of Alloy 36?


Element Composition
Nickel (Ni) 36.0%
Manganese (Mn) 0.1%
Carbon (C) 0.005%
Iron (Fe) Balance

What Are the Physical and Mechanical Properties of Alloy 36?


Property Value
Density 0.291 lb/in3
Specific Gravity 8.05
Tensile Strength 65,000 psi
Yield Strength 38,000 psi
Elongation 35%
Hardness 130 HV
Elastic Modulus 20.5 × 106 psi

What Are the Thermal Expansion Properties of Alloy 36?


Temperature Range Coefficient
30-300°C / 86-572°F 5.5 × 10-6 m/m/°C
30-400°C / 86-752°F 8.4 × 10-6 m/m/°C

Where Is Alloy 36 Used?

  • Hermetic electronic packages
  • Precision instruments
  • Electronic lead frames
  • Sensors and controls
  • Glass-to-metal seals
  • Dimensional stability applications

Among standard nickel-iron sealing alloys, Alloy 36 (Invar®) is recognized for having the lowest thermal expansion and is widely used in precision electronic and instrumentation applications.

Alloy 36 maintains exceptionally low thermal expansion up to approximately 400°F (204°C).

Yes. Alloy 36 is commonly used in precision instruments, measuring devices, and electronic components where dimensional stability is critical.

Yes. Alloy 36 is commonly used in glass-to-metal sealing applications because its expansion characteristics help reduce stress between glass and metal components.

Alloy 36 is available in thicknesses from 0.002" to 0.080" and widths up to 14" (355.6 mm). Custom sizes are available upon request.
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