Kovar®
Kovar is an nickel-iron-cobalt controlled expansion alloy. It is used
for glass, or ceramic to metal seals in electronic and electro-optical
applications. It is magnetic at room temperature.
Machinability
Kovar is readily machined using techniques similar to those used
for stainless steel. The grade is non-hardenable except by cold
working and tends to be soft and gummy. This lack of stiffness
creates the machining problems that exist with the grade, and is
overcome by using slow speeds, high feeds and sharp tools.
Coolants should be used, soluble oil is the coolant of choice.
Machining is improved by machining hardness in the ¼ to ½ hard
cold worked condition. Hot rolled or hot finished surfaces have
some oxide contamination; additional stock removal should be
provided and material should be de-scaled prior to machining.
Chemistry: Typical Analysis
C Mn Si Ni Co Fe
.02 max .30 .20 29.0 17.0 Bal.
Heat Treat Data
Anneal from 1290°F to 2000°F
Typical Anneal-1470°F for 30 minutes.
Not hardenable by heat-treating.
Workability
Readily soft-soldered, brazed or welded.
Physical Properties
Density
0.302/lb cu in.
Specific Electrical Resistance (micro-ohms/cm)
49
Specific Electrical Resistance (ohms/CMF)
294
Thermal Conductivity (watts/cm/°C approx)
0.142
Modulus of Elasticity (psi)
20 x 10³
Curie Point °C (approx)
435
Melting Point °C (approx)
1450
Mechanical Properties
Tensile Strength
75,000 psi
Yield Point
500,500 psi
Proportional Limit
32,300
Hardness
80 RB
Elongation
30%
Thermal Expansion
Temperature Average Coefficient of Expansion
30°C to 200°C 5.5 x 10(-6)
30°C to 300°C 5.1 x 10(-6)
30°C to 400°C 4.9 x 10(-6)
30°C to 450°C 5.3 x 10(-6)
30°C to 500°C 6.2 x 10(-6)
Kovar is an nickel-iron-cobalt controlled expansion alloy. It is used
for glass, or ceramic to metal seals in electronic and electro-optical
applications. It is magnetic at room temperature.
Machinability
Kovar is readily machined using techniques similar to those used
for stainless steel. The grade is non-hardenable except by cold
working and tends to be soft and gummy. This lack of stiffness
creates the machining problems that exist with the grade, and is
overcome by using slow speeds, high feeds and sharp tools.
Coolants should be used, soluble oil is the coolant of choice.
Machining is improved by machining hardness in the ¼ to ½ hard
cold worked condition. Hot rolled or hot finished surfaces have
some oxide contamination; additional stock removal should be
provided and material should be de-scaled prior to machining.
Chemistry: Typical Analysis
C Mn Si Ni Co Fe
.02 max .30 .20 29.0 17.0 Bal.
Heat Treat Data
Anneal from 1290°F to 2000°F
Typical Anneal-1470°F for 30 minutes.
Not hardenable by heat-treating.
Workability
Readily soft-soldered, brazed or welded.
Physical Properties
Density
0.302/lb cu in.
Specific Electrical Resistance (micro-ohms/cm)
49
Specific Electrical Resistance (ohms/CMF)
294
Thermal Conductivity (watts/cm/°C approx)
0.142
Modulus of Elasticity (psi)
20 x 10³
Curie Point °C (approx)
435
Melting Point °C (approx)
1450
Mechanical Properties
Tensile Strength
75,000 psi
Yield Point
500,500 psi
Proportional Limit
32,300
Hardness
80 RB
Elongation
30%
Thermal Expansion
Temperature Average Coefficient of Expansion
30°C to 200°C 5.5 x 10(-6)
30°C to 300°C 5.1 x 10(-6)
30°C to 400°C 4.9 x 10(-6)
30°C to 450°C 5.3 x 10(-6)
30°C to 500°C 6.2 x 10(-6)
Robin Materials Inc
ISO 9001:2000
ISO 9001:2000
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