Invar plates
Invar plates
Available in many forms, we can offer a bespoke solution that meets your exact requirements and specification for your Invar 36 application, be it from Plate, Bar, Sheet, Coil or Wire. With over 15 years’ experience, our team has a combined wealth of knowledge about Invar 36 and its different characteristics, so we can guarantee you will find the product that fits your requirements.
|
Property |
Super Invar 32.5 (ASTM F-1684) |
Carpenter Invar 36 (ASTM F-1684) |
Free-Cut Invar 36 (ASTM F-1684) |
Low Expansion 39 (ASTM B-753) |
Low Expansion 42 (ASTM B-753) |
Low Expansion 45 (ASTM B-753) |
Low Expansion 49 (ASTM B-753) |
Glass Sealing 52 (ASTM F-30) |
|
Composition: |
||||||||
|
Carbon (%) |
0.05 |
0.05 |
0.10 |
0.05 |
0.05 |
0.05 |
0.05 |
<0.01 |
|
Manganese (%) |
0.35 |
0.35 |
0.90 |
0.40 |
0.10 |
0.50 |
0.50 |
0.50 |
|
Silicon (%) |
0.30 |
0.30 |
0.35 |
0.25 |
0.20 |
0.25 |
0.40 |
0.25 |
|
Nickel (%) |
32.0 |
36.0 |
36.0 |
39.0 |
42.0 |
45.0 |
47.5 |
50.5 |
|
Other Elements |
Co ≤ 5.25, Fe bal. |
Fe bal. |
Se 0.20, Fe bal. |
Fe bal. |
Fe bal. |
Fe bal. |
Fe bal. |
Fe bal. |
|
Specific Gravity |
8.10 |
8.05 |
8.05 |
8.08 |
8.12 |
8.20 |
8.25 |
8.30 |
|
Thermal Conductivity (W/cm °C) |
10 |
10 |
10 |
11 |
11 |
16 |
17 |
16 |
|
Electrical Resistivity (µΩ-cm) |
80 |
82 |
82 |
71 |
67 |
55 |
48 |
43 |
|
Curie Temperature (°C) |
260 |
280 |
280 |
340 |
380 |
440 |
500 |
530 |
|
Specific Heat (cal/g-°C) |
0.12 |
0.12 |
0.12 |
0.12 |
0.12 |
0.12 |
0.12 |
0.12 |
|
Typical Coefficients of Thermal Expansion (as annealed) (x10-4/°C): |
||||||||
|
25 to 93°C |
0.72 |
1.6 |
1.8 |
2.3 |
5.8 |
7.9 |
8.5 |
10.0 |
|
149°C |
/ |
2.0 |
2.3 |
2.7 |
3.6 |
7.7 |
8.5 |
10.1 |
|
260°C |
/ |
4.1 |
4.5 |
3.2 |
5.4 |
7.4 |
8.5 |
10.2 |
|
371°C |
/ |
7.2 |
7.9 |
5.8 |
5.8 |
7.2 |
8.5 |
10.1 |
|
Tensile Strength (MPa, ksi) |
483 (70) |
517 (75) |
517 (75) |
517 (75) |
517 (75) |
565 (82) |
517 (75) |
517 (75) |
|
Yield Strength (MPa, ksi) |
276 (40) |
276 (40) |
276 (40) |
276 (40) |
276 (40) |
276 (40) |
276 (40) |
276 (40) |
|
Elongation in 2 in. (%) |
30 |
30 |
30 |
30 |
30 |
30 |
30 |
30 |
|
Hardness, Rockwell B Scale |
80 |
80 |
80 |
80 |
80 |
80 |
80 |
80 |
|
Elastic Modulus (GPa, Msi) |
144 (21.0) |
141 (20.5) |
141 (20.5) |
144 (21.0) |
148 (21.5) |
144 (21.0) |
166 (24.0) |
165 (24.0) |
Magnetic Properties and Scientific Significance
The unusual physical properties of Invar-composition alloys have attracted significant scientific interest. In 1960, Sedov and colleagues proposed that the magnetic anomalies in Invar alloys result from "latent antiferromagnetism." This hypothesis suggested that in the gamma phase of FeNi Invar alloy, the exchange interaction energy parameters between neighboring atoms (Ni-Ni and Ni-Fe) have opposite signs, with negative values for Fe-Fe atoms. Experimental evidence later confirmed the potential for antiferromagnetism in the gamma-iron lattice through characteristic temperature-dependent susceptibility measurements and Mössbauer spectroscopy.
Using rotational hysteresis measurements of Fe-Ni alloys, Nakamura estimated that the antiferromagnetically ordered regions demonstrate Néel temperatures (TN) between 35-50°K. Further neutron-diffraction investigations by Dubinin and colleagues confirmed the coexistence of paramagnetic and antiferromagnetic phases within Invar materials.
Thermal Expansion Characteristics
Invar (UNS K93601) and related binary iron-nickel alloys exhibit low expansion coefficients only within a specific temperature range, as illustrated in Figure 1. The thermal behavior can be characterized by several distinct regions:
- Region A to B:High coefficient of expansion at low temperatures
- Region B to C:Decreasing coefficient
- Region C to D:Minimum expansion (the "Invar effect" region)
- Region D to E:Increasing coefficient with rising temperature
- Region E to F:Normal expansion similar to constituent metals
The practical minimum expansivity exists only within the C to D temperature range.
