4J29-Kovar alloy strip Kovar bar/kovar sheet/kovar tube

Product Detail

Common Trade Names:Kovar Alloy,4J29,UNS K94610(FeNi29Co17),29HК Kovar,KV-1,29HК-BИ,Werkstoff Nr.1.3981

This alloy also caleed Glass sealed and controlled expansion alloy,The alloy has a linear expansion coefficient similar to that of silicon boron hard glass at 20-450°C, a higher Curie point, and good low-temperature structural stability. The oxide film of the alloy is dense and can be well wetted by glass . It does not interact with mercury and is suitable for use in mercury-containing discharge meters. It is the main sealing structure material for electric vacuum devices.


Kovar Alloy Chemical Composition
C Cr Ni Mo Si Mn P S Fe Co Cu
≤0.03 ≤0.2 28.5-29.5 ≤0.2 ≤0.3 ≤0.5 ≤0.02 ≤0.02 balance 16.8-17.8 ≤0.2
Kovar Physical properties
Density(g/cm3) Thermal conductivity(W/m·K)   Electrical resistivity(μΩ·cm)
8.3 17 45
Kovar Average expansion coefficient
Alloy Grades


The average linear expansion coefficient a,10-6/ oC
















kovar 5.9 5.3 5.1 5.3 6.2 7.8 9.2 10.2

Kovar  average linear expansion coefficient in line


Alloy Grades Specimen heat treatment system The average linear expansion coefficient α,10-6/ oC
Kovar 20-300 oC 20-400 oC 20-450 oC
In hydrogen atmosphere heated to 900 ± 20 oC, insulation 1h, and then heated to 1100 ± 20 oC, insulation 15min, to not more than 5 oC / min rate of cooling to below 200 oC released -----  4.6-5.2 5.1-5.5

Kovar  typical expansion coefficient    

Alloy Grades The average linear expansion coefficient a,10-6/ oC
 Kovar 20-200oC 20-300 oC 20-400oC 20-450oC 20-500oC 20-600oC 20-700oC 20-800oC
5.9 5.3 5.1 5.3 6.2 7.8 9.2 10.2

Kovar Alloy Available Products in Sekonic Metals

Inconel 718 bar,inconel 625 bar

Kovar Bars & Rods

Round bars/Flat bars/Hex bars,     Size From 8.0mm-320mm, Used for bolts,fastners and other spare parts

welding wire and spring wire

Kovar wire

Supply in welding wire and spring wire in coil form and cut length.

Sheet & Plate

Kovar sheet & plate

Widths up to 1500mm and lengths up to 6000mm,Thickness from 0.1mm  to 100mm.

Kovar seamless tube & Caplliary Tube

Standards size and  customized dimension can be produced by us with small tolerance

inconel strip,invar stirp,kovar stirp

Kovar strip & coil

Soft condition and hard condition with AB bright surface, width up to 1000mm

Why Inconel Kovar ?

1.Kovar has a wide usage in the electronics industry, such as metal parts bonded to hard glass envelopes. These parts are used for such devices as power tubes and X-ray tubes, etc.
2.In the semiconductor industry kovar is used in hermetically sealed packages for both integrated and discrete circuit devices.
3.Kovar is provided in a variety of forms to facilitate efficient manufacturing of various metal parts. It has thermal expansion characteristics matching those of hard glass. Used for matched expansion joints between metals and glass or ceramics.
4.Kovar alloy is a vacuum melted, iron-nickel-cobalt, low expansion alloy whose chemical composition is controlled within narrow limits to assure precise uniform thermal expansion properties. Extensive quality controls are employed in the manufacture of this alloy to ensure uniform physical and mechanical properties for ease in deep drawing, stamping and machining.

Kovar Alloy Application field:

● Kovar alloy has been used for making hermetic seals with the harder Pyrex glasses and ceramic materials.
●This alloy has found wide application in power tubes, microwave tubes, transistors and diodes. In intergrated circuits, it has been used for the flat pack and the dual-in-line package.

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