Low Expansion Coefficient Kovar Tube For Electrical Vacuum Element
(Common Name: Invar, FeNi36, Invar Standard, Vacodil36)
Ualloy-4J36 (Invar), also known generically as FeNi36 (64FeNi in the US), is a nickel-iron alloy notable for its uniquely low coefficient of thermal expansion (CTE or α).
Ualloy-4J36 (Invar) is used where high dimensional stability is required, such as precision instruments, clocks, seismic creep gauges, television shadow-mask frames, valves in motors, and antimagnetic watches. In land surveying, when first-order (high-precision) elevation leveling is to be performed, the Level staff (leveling rod) used is made of Invar, instead of wood, fiberglass, or other metals. Invar struts were used in some pistons to limit their thermal expansion inside their cylinders.
Normal composition%
| Ni |
35~37.0 |
Fe |
Bal. |
Co |
- |
Si |
≤0.3 |
| Mo |
- |
Cu |
- |
Cr |
- |
Mn |
0.2~0.6 |
| C |
≤0.05 |
P |
≤0.02 |
S |
≤0.02 |
|
|
Typical Physical properties
| Density (g/cm3) |
8.1 |
| Electrical resistivity at 20ºC(ohm.mm2/m) |
0.78 |
| Temperature factor of resistivity(20ºC~200ºC)X10-6/ºC |
3.7~3.9 |
| Thermal conductivity, λ/ W/(m*ºC) |
11 |
| Curie point Tc/ ºC |
230 |
| Elastic Modulus, E/ Gpa |
144 |
Coefficient of expansion
| θ/ºC |
α1/10-6ºC-1 |
θ/ºC |
α1/10-6ºC-1 |
| 20~-60 |
1.8 |
20~250 |
3.6 |
| 20~-40 |
1.8 |
20~300 |
5.2 |
| 20~-20 |
1.6 |
20~350 |
6.5 |
| 20~-0 |
1.6 |
20~400 |
7.8 |
| 20~50 |
1.1 |
20~450 |
8.9 |
| 20~100 |
1.4 |
20~500 |
9.7 |
| 20~150 |
1.9 |
20~550 |
10.4 |
| 20~200 |
2.5 |
20~600 |
11.0 |
Typical Mechanical properties
| Tensile Strength |
Elongation |
| Mpa |
% |
| 641 |
14 |
| 689 |
9 |
| 731 |
8 |
Temperature factor of resistivity
| Temperature range, ºC |
20~50 |
20~100 |
20~200 |
20~300 |
20~400 |
| aR/ 103 *ºC |
1.8 |
1.7 |
1.4 |
1.2 |
1.0 |
| The heat treatment process |
| Annealing for stress relief |
Heated to 530~550ºC and hold 1~2 h. Cold down |
| annealing |
In order to eliminate hardening, which be bring out in cold-rolled, cold drawing process. Annealing needs heated to 830~880ºC in vacuum,hold 30 min. |
| The stabilization process |
In protective media and heated to 830 ºC, hold 20min. ~ 1h, quench
Due to the stress generated by quenching, heated to 315ºC,hold 1~4h.
|
| Precautions |
Can not be hardened by heat treatment,
Surface treatment can be sandblasting, polishing or pickling.
Alloy can be used 25% hydrochloric acid pickling solution at 70 ºC to clear oxidized surface
|
FAQ
1. What's the minimum quantity customer can order?
If we have your size in stock, we can provide any quantity you want.
If we do not have, for spool wire, we can produce 1 batch,6m/order.
2. How can you pay for small sample amount?
We have Western union account, wire transfer for sample amount also ok.
3. Customer do not have express account. How will us arrange the delivery for sample order?
Just need to provide your address information, we will check the express cost, you can arrange the express cost together with sample value.
4. What's our payment terms?
We can accept LC T/T payment terms, it also depending on delivery and total amount. Let's talk more in details after getting your detailed requirements.
5. Do you provide free samples?
If you want several meters and we have stock of your size, we can provide, customer need to bear the International express cost.
6. What's our working time?
We will give you reply through email/phone Online contact tool within 24 hours. No matter working day or holidays.
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