Kovar alloy, ASTM F15, Nilo-K,UNS K94610(FeNi29Co17),Chinese 4J29
Kovar Alloy, is a controlled expansion alloy. It is a Nickel Iron alloy with 29% Nickel, 17% Cobalt and the remaining balance is Iron.
Forms: Sheet/Plate, Bar/Rod/Wire/Coil,Capillary/Pipe/Tube

Description

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, coining, stamping and machining.

Application

Kovar alloy has been used for making hermetic seals with the harder Pyrex glasses and ceramic materials. This alloy has found wide use in application where high reliability is a necessity. In power tubes, microwave tubes, transistors, diodes, inter-grated circuits and has been used for the flat pack and the dual-in-line package.

parameter

Cross Reference

Russia	USA	UK	Japan	France	Germany
29HK	Kovar	Nilo K	-	Dilver P0	Vacon 12
29HK-ВИ	Rodar Teachallony Glass 29-17	Teleaseal	-	Dilver P1	Silvar

Typical chemistry

C	P	S	Mn	Si	Cu	Cr	Mo	Ni	Co	Fe
≤
0.03	0.020	0.020	0.50	0.30	0.20	0.20	0.20	28.5-29.5	16.8-17.8	Balance

Physical Properties

Specific gravity		8.36
Density	lb/cu in	0.302
	kg/cu m	8359
Thermal conductivity	Btu-in/ft²/hr/°F	120
	W/m-K	17.3
Curie temperature	°F	815
	°C	435
Melting Point	°F	2640
	°C	1450
Modulus of elasticity	psi x 10(6)	20
	MPa x 10(3)	138
Electrical resistivity	ohm-cir mil/ft	294
	microhm-mm	490

Mechanical Properties

Tensile Strength	Ksi MPa	75 518
Yield Strength	Ksi MPa	40 276
Elongation	% in 2 in	30
Typical Hardness Ann	Rockwell	HRB80
Modulus of Elasticity	Mpsi KMPa	30 207

Average Coefficient of Linear Expansion

Heat Treatment of the Samples	Average Coefficient of Linear Expansion
	20～300℃	20～400℃	20～450°C
Heat to temperature of  900±20℃ in the hydrogen, hold for 1h; re-heat to 1100±20℃, hold for 15 min.; cooled to 200℃ at a rate less than 5℃/min		4.6 t o  5.2	5.1 to 5.5

Mean Coefficient of linear expansion at different temperature, ā/(10^-6/K)

Size Range

Sheet	Thickness:0.10mm~3.50mm, width: ≤300mm
Plate	Thickness:3.5mm~40.0mm, width: ≤500mm
Round wire	Thickness:0.10mm~5.0mm
Flat Wire	Dia 0.5mm~Dia 5.0mm, length≤1000
Rod	Dia 5.0mm~Dia 8.0mm, length≤2000
	Dia 8.0mm~Dia 32.0mm, length≤2500
	Dia 32.0mm~Dia180.0mm, length≤1000
Capillary	OD 8.0mm~1.0mm,ID 0.1~8.0 length≤2500
Pipe	OD 120mm~8.0mm,ID 8.0~129 length≤4000

Condition: (With max tolerance) cold rolled, cold drawn, hot rolled , hot forging ,peeled turned ,bright ,bright annealed