The Materials You Need When You Need Them

Invar3 (aka Invar 361, Pernifer 362, NILO 364, Invar Steel)

Invar3 (aka Invar 361, Pernifer 362, NILO 364, and Invar Steel) is a low expansion alloy consisting of 36% Nickel, balance Iron. Invar Alloy exhibits extremely low expansion around ambient temperatures, making Invar Alloy particularly useful in applications where minimum thermal expansion and high dimensional stability is required, such as in precision instruments like optoelectronic devices, optical and laser benches, electronics, and other kinds of scientific instruments.

This alloy is available in two variations. One is the conventional Invar alloy, used generally for its optimum low expansion properties. The second is a variation of the basic alloy known as Free-Cut Invar "36"® alloy (UNS K93050 and ASTM F1684). This alloy has shown improved machinability for applications where high productivity is important. It is also a 36% nickel-iron alloy, but with a small addition of selenium to enhance machinability.

Standard Alloy

The conventional Invar alloy used generally for its optimum low expansion properties. It may have a slightly lower coefficient of thermal expansion than Free Cut Invar

Free-Machining Variation

Free-Cut Invar 36 alloy, the world's first free-machining Invar alloy, has been used by machine shops that are producing high volumes of parts like controls for hot water heaters, filters for microwave instruments, precision parts for optical mounting in lenses, etc.

High-production shops have reported the free-machining alloy to be advantageous also when performing several different machining operations, particularly when parts have intricate shapes and/or require working to close tolerances.

Compared with the conventional Invar grade, the downside for Free-Cut Invar 36 alloy is negligible. Its coefficient of thermal expansion is only slightly higher than that of the basic alloy; not enough, generally, to make a difference in part performance.

With the free-machining alloy, there is a minimal loss in both transverse toughness and corrosion resistance. It also may be necessary to clean and passivate the free-cut alloy to remove selenides from the surface.

However, a good case can be made for the free-cut alloy because it machines without a hassle and permits parts productivity gains frequently reaching 250%. From the machinist's point-of-view, it becomes difficult to justify not using the free-machining grade.

Invar Products

Ed Fagan Inc. stocks Invar in a variety of forms and dimensions. Strip, sheet and Plate are stocked as standard alloy. Bar stock is stocked in the Free Machining variety.

Below are most of the standard stock form/sizes. If you do not see the size or form of Invar that you require, please call one of our materials experts; our sales people are very knowledgeable and can assist you. We can cut, slit, shear, or center less grind Invar to your exact specifications, and we also have tremendous versatility when it comes to custom sizes, packages, and unusual materials

Invar Rod (Free Machining Variety)

Invar Rod Diameter

Invar Rod Diameter

.125” Invar Rod

1.125” Invar Rod

.187” Invar Rod

1.250” Invar Rod

.250” Invar Rod

1.500” Invar Rod

.3125” Invar Rod

1.625” Invar Rod

.375” Invar Rod

1.750” Invar Rod

.500” Invar Rod

2.000” Invar Rod

.625” Invar Rod

2.250” Invar Rod

.750” Invar Rod

2.500” Invar Rod

.875” Invar Rod

3.000” Invar Rod

1.000” Invar Rod

6.000” Invar Rod

 

Invar Sheet

Invar Sheet Thickness

Invar Sheet Thickness

.030” Invar Sheet

.062” Invar Sheet

.040" Invar Sheet

.100” Invar Sheet

.050” Invar Sheet

.125” Invar Sheet

 

Invar Plate

Invar Plate Thickness

Invar Plate Thickness

.150” Invar Plate

.875” Invar Plate

.187” Invar Plate

1.000” Invar Plate

.250” Invar Plate

1.500” Invar Plate

.375” Invar Plate

2.000” Invar Plate

.500” Invar Plate

2.500” Invar Plate

.625” Invar Plate

3.000” Invar Plate

.750” Invar Plate

4.000” Invar Plate

 

Invar Applications

Positioning devices • Bimetal thermostats • Advanced composite molds for aerospace industry • Dimensionally stable instruments and optical devices • Containers for LNG tankers • Transfer lines for LNG • Echo boxes and filters for mobile telephones • Magnetic shielding • Small electrical transformers • Metrology devices • Scientific instruments • Electrical circuit breakers • Temperature regulators • Clock balance wheels • Pendulum clocks • Precision condenser blades • Radar and microwave cavity resonators • Special electronic housings • Seals, spacers, and specialized frames • High voltage transmission lines • CRT applications: shadow masks, deflection clips, and electron gun components.

Invar Properties

 

Invar Alloy Physical Properties

Density

lb/cu in

0.291

Specific Gravity

 

8.05

Curie Temp

°F

535

 

°C

279

Melting Point

°F

2600

 

°C

1427

Electrical Resistivity

Micro-ohm-cm

84

 

ohm-cir mil/ft

495

Thermal Conductivity

W/cm °C

0.10

 

BTU-in/sq. ft-hr-

72.6

Specific Heat

Cal/g- °C

0.12

 

BTU/lbm- °F

0.12

Thermal Expansion

ppm / °F (75°F to 842°F)

4.9

 

ppm / °C (25°C to 450°C)

8.9


Invar Mechanical Properties

Tensile Strength

ksi

75

 

MPa

518

Yield Strength

ksi

40

 

MPa

276

Elongation

% in 2 in.

34

Typical Hardness Ann.

Rockwell HRB

80

Modules of Elasticity

Mpsi

20.5

 

kMPa

141


Invar Chemistry

maximum % unless noted

Iron

Bal

Nominal Nickel

36

Nominal Cobalt

0.5

Carbon

0.05

Silicon

0.40

Sulfur

0.015

Chromium

0.25

 

 

Invar Specifications

ASTM F-1684

MIL 1-23011 CL 7

AMS 1-23011 CL 7


Invar Alloy Linear Coefficient of Thermal Expansion

Degree C

 

Degree C

 

30-100

0.8 - 1.6

30-450

8.5 - 9.2

30-150

--

30-475

--

30-200

1.3 - 2.1

30-500

9.7

30-250

--

30-525

--

30-300

4.92

30-550

--

30-325

--

30-600

11.4

30-350

6.2 - 7.0

30-700

12.7

30-375

--

30-800

13.5

30-400

7.8

30-900

13.9

30-425

--

30-1000

--

 

ED FAGAN INC. supplies the highest quality special purpose metals and alloys for Aerospace/Aviation, Defense, Electronics, Magnetic, Medical, Lighting, Optical, Telecommunications, Ceramics, Heat Treating, and other high-technology industries.

1. Trademark Carpenter Technology Corp., Reading PA
2. Trademark ThyseenKrupp-VDM, Germany
3. Trademark Imphy Alloys, France
4. Trademark Special Metals Corporation, USA

Controlled Expansion Alloys

Ed Fagan Inc. stocks a variety of similar alloys for low expansion, controlled expansion, glass-to-metal or ceramic sealing applications that may also satisfy your needs. EFI carries:
Invar
Super Invar
Kovar
42 Alloy
46 Alloy
48 Alloy
52 Alloy

And we also have a large selection of other types of specialty metals and alloys for high technology applications, including:
Electrical/Electronic Nickel
Soft Magnetic Alloys
Refractory Metals and Alloys
Hard to Find Materials