Kovar Alloy

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Introduction:
Kovar alloy has stable performance, mainly applying to the glass sealing of lead wire, chassis, shell holder, etc., in electrical vacuum components, transmitting valve, oscillating tube, ignitron, magnetron, transistor, sealing plug, electric relay and integrated circuit. The glass should match with the expansion coefficient of the alloy in application. Its cryogenic structural stability is strictly tested according to the use temperature. During the processing, proper heat treatment should be conducted to ensure that the material has good deep drawability and high elongation. When using forging material, its gas tightness should be tested strictly.

Supply of Kovar alloy

Shape	Size
Wire	D=0.1~8mm
Strip	W= 5~250mm	T= 0.1mm
Foil	W= 10~100mm	T= 0.01~0.1mm
Rod	D=8~100mm	L=50~1000mm

Grades
UNS K94610, ASTM F15, GB 4J29

Chemical composition (%)

Ni	28.5~29.5	Fe	Bal.	Co	16.8~17.8	Si	≤0.3
Mo	≤0.2	Cu	≤0.2	Cr	≤0.2	Mn	≤0.5
C	≤0.03	P	≤0.02	S	≤0.02

Tensile strength, MPa

State No.	State	Wire alloy	Strip alloy
R	Soft	≤585	≤570
1/4I	1/4 Hard	585~725	520~630
1/2I	1/2 Hard	655~795	590~700
3/4I	3/4 Hard	725~860	600~770
I	Hard	≥850	≥700

Physical property

Density (g/cm³)	8.2
Resistivity under 20℃(Ωmm²/m)	0.48
Resistance temperature coefficient (20℃~100℃)X10-5/℃	3.7~3.9
Curie point, Tc/ ℃	430
Elasticity modulus, E/ Gpa	138

Expansion coefficient

θ/℃	α1/10-6℃-1	θ/℃	α1/10-6℃-1
20~60	7.8	20~500	6.2
20~100	6.4	20~550	7.1
20~200	5.9	20~600	7.8
20~300	5.3	20~700	9.2
20~400	5.1	20~800	10.2
20~450	5.3	20~900	11.4

Heat conductivity

θ/℃	100	200	300	400	500
λ/ W/(m*℃)	20.6	21.5	22.7	23.7	25.4

Heat conductivity

Stress-relief annealing	Be heated to 470~540℃ and preserve heat for 1~2 h. Be cooled in the furnace.
Anneal	Be heated to750~900℃ in vacuum
Holding time	14 min~1h
Cooling methods	Be cooled to 200 ℃ at a speed of no more than 10 ℃/min

Index
nickel alloy, alloy pipe