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Kovar - UNS K94610 Sheet

Kovar (Alloy K) Sheet is a nickel-iron-cobalt controlled-expansion alloy containing 29% nickel.

The chemical composition is well controlled so as to provide low, uniform, thermal expansion property for this alloy. The following sections will discuss in detail about super alloy KOVAR.

Kovar ASTM F15, UNS K94610 Sheet is a controlled expansion alloy. It is a Nickel Iron alloy with 29% Nickel, 17% Cobalt and the remaining balance is Iron. The expansion characteristics of Nilo k (Kovar) match both borosilicate (or Pyrex) glasses and alumina ceramics, making it one of the most popular of the controlled expansion alloys for hermetic sealing applications (Glass to Metals Sealing). Nilo K (Kovar) is produced to ensure good properties for machining and deep drawing, and is a porosity free product.

Kovar (Nilo K) Sheet not only has thermal expansion similar to glass, but its nonlinear thermal expansion curve can often be made to match a glass, thus allowing the joint to tolerate a wide temperature range. Chemically, it bonds to glass via the intermediate oxide layer of nickel oxide and cobalt oxide; the proportion of iron oxide is low due to its reduction with cobalt. The bond strength is highly dependent on the oxide layer thickness and character.The presence of cobalt makes the oxide layer easier to melt and dissolve in the molten glass. A grey, grey-blue or grey-brown color indicates a good seal. A metallic color indicates lack of oxide, while black color indicates overly oxidized metal, in both cases leading to a weak joint.


  • Resists erosive wear
  • Good impact & thermal shock resistance
  • Resists heat & oxidation
  • Abrasion & corrosion resistant
  • Resists seizing & galling
  • Good strength
  • Meets UNS R30006 specifications


  • Automobile Industry
  • Construction
  • Pharmaceutical/Chemical Industry
  • Oil & Gas Industry

Also see 15-5 stainless steel plate


  • UNS : K94610
  • Specifications : MIL-I-23011 CL 1, ASTM F15, AMS 7727
  • International Specifications: Werkstoff Nr. 1.3981 DIN 17745 AFNOR NF A54-301 S.E.W. 385

Chemical Composition

Kovar Chemical Composition (Basic Density 8.36)
Weight % Ni Fe Co C Mn Si Al Cr Mg Zr Ti Cu Mo
Alloy K
29.0 53.0 17.0 0.04 max 0.50 max 0.20 0.10 max 0.20 max 0.10 max 0.10 max 0.10 max 0.20 max 0.20 max

Mechanical Properties

Material Condition Yield Strength (0.1% Offset) Tensile Strength Elongation %
psi MPa psi MPa
Alloy K
Annealed 49,000 340 75,000 520 42

Calico Metal Alloys LLP export products to countries like UAE, Bahrain, Italy, Indonesia, Malaysia, United States, Mexico, Chine, Brazil, Peru, Nigeria, Kuwait, Jordan, Dubai, Thailand (Bangkok), Venezuela, Iran, Germany, UK, Canada, Russia, Turkey, Australia, New Zealand, Sri Lanka, Vietnam, South Africa, Kazakhstan & Saudi Arabia.

HASTELLOY, HAYNES and C-22 are registered trade names of Haynes International, Inc., MONEL & INCONEL are registered trade names of INCO family of companies., NITRONIC is a registered trade name of Armco Inc., CARPENTER & 20Cb-3 are registered trade names of Carpenter Technology Corporation., FERRALIUM is a registered trade name of Langley Alloys, LTD.