
ASTM F15 precision alloy kovar material 4J29 round bar rod price per kg
Glass sealed and controlled expansion Kovar alloys
* kovar alloy, ASTM F15, Nilo-K, UNS K94610 (FeNi29Co17), Chinese 4J29
*Specifications:ASTM F15; DIN 17745; S.E.W. 385; Werkstoff Nr. 1.3981; AFNOR NF A54-301
Kovar Alloy, also know as ASTM F-15, NILO K, Pernifer 2918, Rodar, and Dilvar P1 is Nickel-Iron-Cobalt, controlled expansion alloy containing 29% Nickel.
It’s coefficient of expansion (which decreases with rising temperature to the inflection point), matches the expansion rate ofborosilicate glasses and aluminia ceramics.
Applications include glass to metal seals in applications requiring high reliability or resistance to thermal shock, ie.high~power transmitting valves, transistor leads and heaters and photography flash bulbs.
| Trade Name | UNS No. | Specifications | |
Rod | Strip | Wire | Sheet |
| | | | | | | |
| | | | | | | |
| | | | | | | |
| | | | | | | |
| | | | | | | |
| | | | | | | |
| | | | | | | |
| | | | | | | |
Item | 1J33 | 3J01 | 3J9 | 4J29 | 4J32 | 4J33 | 4J45 | FeNi50 | Invar36 |
C | ≤0.05 | ≤0.05 | 0.22-0.26 | ≤0.03 | ≤0.05 | ≤0.03 | ≤0.05 | ≤0.05 | ≤0.1 |
Mn | ≤0.05 | ≤1.00 | 1.80-2.20 | ≤0.5 | 0.2-0.6 | ≤0.5 | ≤0.8 | ≤0.8 | ≤0.5 |
Fe | Rest |
P | ≤0.020 | ≤0.020 | ≤0.03 | ≤0.02 | ≤0.02 | ≤0.02 | ≤0.02 | ≤0.02 | ≤0.006 |
S | ≤0.020 | ≤0.020 | ≤0.020 | ≤0.02 | ≤0.02 | ≤0.02 | ≤0.02 | ≤0.02 | ≤0.04 |
Si | 0.30-0.6 | ≤0.80 | 1.30-1.70 | ≤0.3 | ≤0.2 | ≤0.3 | ≤0.3 | ≤0.3 | ≤0.35 |
Ni | 32.8-33.8 | 34.5-36.5 | 9.0-10.5 | 28.5-29.5 | 31.5-33 | 28.5-29.5 | 44.5-45.5 | 49.5-50.5 | 35-38 |
Al | 1.0-2.0 | 1.00-1.80 | -- | -- | -- | -- | ≤0.1 | ≤0.1 | -- |
Co | -- | -- | -- | 16.8-17.8 | 3.2-4.2 | 16.8-17.8 | - | - | - |
Ti | - | 2.70-3.20 | - | - | - | - | - | - | - |
Cu | - | -- | -- | -- | ≤0.2 | 0.4-0.8 | ≤0.2 | -- | -- |
Cr | -- | 11.5-13.0 | 19.0-20.5 | ≤0.2 | -- | ≤0.2 | -- | -- | -- |
Mo | -- | -- | 1.60-1.85 | ≤0.2 | -- | ≤0.2 | -- | -- | -- |




Kovar (also known as KV-1 or ASTM F15) is a nickel-iron alloy that finds wide applications in the field of electronics due to its thermal expansion coefficient that matches that of borosilicate glass. Here are some of the application areas of Kovar:
1. Electronic device packaging: Kovar is widely used in the packaging of semiconductor devices, integrated circuits, and other electronic components to provide stable packaging and protect electronic components from environmental influences.
2. Optoelectronics: Kovar finds widespread application in lasers, photodetectors, and other optical components due to its excellent thermal expansion coefficient and stability.
3. Aerospace: Kovar is widely used in guidance systems, navigation systems, and other devices in the aerospace field due to its high strength, corrosion resistance, and high-temperature resistance.
In summary, Kovar finds wide applications in the packaging of electronic components or protection of optoelectronic components due to its thermal expansion coefficient that matches that of borosilicate glass.







