Invar 36 is an iron-based nickel alloy with 36 % nickel. A special feature of this material is its low coefficient of thermal expansion below its Curie temperature of 280°C.
It maintains nearly constant dimensions at temperatures below -150°C (-238°F) all the way up to 260°C (500°F) which is critical to cryogenics.
Invar 36 Nickel-iron alloy also referred to as the EN 1.3912 and UNS K93600 alloy.
Invar 36 also has excellent mechanical properties and a low tendency to fatigue in cryogenic environment.
Fields of application are components that require both a high reliability and a high dimensional stability.
For example, Invar 36 is used for space equipment, clocks, valves in engines, bimetallic thermostats, optic and laser systems, and precision instruments.
The chemical composition of Invar 36 Nickel-iron Alloy
| Alloy | % | Ni | Cr | Fe | C | Mn | Si | P | S |
| Invar 36 | Min. | 35 | Balance | 0.2 | |||||
| Max. | 37 | 0.50 | 0.05 | 0.6 | 0.5 | / | 0.001 |
The mechanical properties of Invar 36 Nickel-iron Alloy
| Alloy Grade | Tensile Strength Rm N/mm2 | Yield Strength RP0.2 N/mm2 | Elongation A5 % | Brinell Hardness HB |
| Invar 36 | 490 | 240 | 42 | ≤200 |
Special Properties of Invar 36 Nickel-iron Alloy
FeNi36 represents a nickel-iron alloy with a nickel content of 36%, exhibiting the lowest thermal expansion among all metals and alloys within the temperature range from room temperature to approximately 230°C.
This alloy, FeNi36, possesses ductility, excellent weldability, and machinability comparable to austenitic stainless steel. Notably, it is resistant to stress corrosion cracking.
The average coefficient of thermal expansion (CTE) for FeNi36, spanning 20-100°C, is below 1.3 x 10-6°C-1. It has a Curie point at 230°C, and its density stands at 8.1 kg.m-3.
Uses And Applications of Invar 36 Nickel-iron Alloy
- Telecommunications
- aeronautical and aerospace engineering
- cryogenic engineering (liquefied natural gas tankers)
- The measurement and control instruments work temperature lower than 200ºC, such as temperature regulating device
- Film framework
- Shadow mask
- CRP components of the aviation industry temper die
Conclusion
Invar 36 nickel-iron alloy plays a crucial part in so many of people’s household controls and office appliances.
Other applications for these special alloys are continuing to be found in industry for advanced electronic components, filters in mobile phone networks and even as tank membranes for massive liquefied natural gas transport ships.
Considering these aspects, Invar 36 nickel-iron alloy strip becomes a viable choice after hot and cold roleld and slitting processes similar to austenitic stainless steels strips.
