Kovar® is a registered trademark of Carpenter Technology Corporation.

Chemistry By % Weight

C 0.02% Max
Co 17%
Fe Balance
Mn 0.3%
Ni 29%
Si 0.2%

Typical Mechanical Properties

Ultimate Tensile Strength 75,000 PSI
Yield Strength 50,000 PSI
Elongation @ Break 30%
Modulus of Elasticity 20,000 KSI
Poisson’s Ratio 0.317

Typical Physical Properties

Density 0.302 lbs/cu in
Melting Point 1450° C
Electrical Resistivity @ RT 4.9 Microhm-cm
Thermal Conductivity @ RT 17.3 W/m-K
Coefficient of Thermal Expansion
Linear at 20° C
3.26 µin/in-°F
At 250° 2.85 µin/in-°F
At 500° C 3.42 µin/in-°F

Kovar® is a vacuum melted Fe-Ni-Co low expansion alloy that has its chemical composition controlled to tight tolerances assuring precise and uniform thermal expansion properties. Kovar is commonly used for making hermetic seals in hard glass. It has also found wide application in power tubes, microwave tubes, diodes and transistors.


H. Cross Company can provide Kovar in wire, ribbon, strip, sheet and foil sizes to suit your particular needs. Please refer to our Typical Dimension and Tolerances page for general size ranges of products. If you do not see the size range you are interested in please Contact Us by email or phone us with your specific requirements.