Electrical Steel / KOVAR

KOVAR is a nickel-cobalt ferrous alloy that has minimal thermal expansion characteristics similar to borosilicate glass. The material provides a reliable and predictable rate of contraction and expansion within specific temperature ranges. Kovar was created to provide the glass-to-metal seal required for electronic elements to be sealed to hard glasses during assembly. This alloy is used in products such as vacuum systems for chemistry and other scientific fields, as well as electronic equipment like light bulbs, vacuum tubes, high-power transmitting valves, and transistor leads / headers. (UNS #K94610)

Chemical Makeup

Element Min Max
Carbon, C - 0.04
Manganese, Mn - 0.5
Silicon, Si - 0.2
Chromium - 0.2
Molybdenun - 0.2
Nickel, Ni - 29
Copper, Cu - 0.2
Cobalt, Co - 17
Magnesium, Mg - 0.1
Aluminum, Al - 0.1
Titanium, Ti - 0.1
Zirconium, Zr - 0.1
Ti+Al+Mg+Zr - 0.2

Common Applications

  • Aerospace Aerospace
  • Power Generation Power Generation
  • Industrial Industrial


  • Minimal Thermal Expansion
  • Glass To Metal Seal

We stock KOVAR to the following specifications:

  • AMS-I-23011 CL 1
  • ASTM-F-15
  • MIL-I-23011 CL 1

Click on a cross-section to see the sizes we stock:

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