Electrical Steel / INVAR 36 FM

INVAR 36 FM (Free-Machining) is a 36% nickel-iron alloy, but with a small addition of selenium to enhance machinability. This material has shown improved machinability for applications where high productivity is important. The free-machining alloy is advantageous to high-production shops when producing parts that have intricate shapes and/or require working to close tolerances. INVAR 36 is also known for its unique low expansion properties. The material has a rate of thermal expansion approximately one tenth that of carbon steel at temperatures up to 400 oF (204 oC). This characteristic makes the alloy ideal for products that require minimal dimensional change due to temperature variation and products where motion is desired when the temperature changes. INVAR 36 FM is used to produce electronic devices, aircraft controls, controls for hot water heaters, bimetallic thermostats, optical systems, and laser systems. (UNS K93050)

Chemical Makeup

Element Min Max
Carbon, C - 0.15
Manganese, Mn - 1
Silicon, Si - 0.35
Nickel, Ni 35 36.5
Selenium, Se 0.15 0.25

Common Applications

  • Aerospace Aerospace
  • Power Generation Power Generation
  • Industrial Industrial


  • Great Machinability
  • Low Expansion Properties

We stock INVAR 36 FM to the following specifications:

  • MBO-160-051 CHEM ONLY
  • MIL-S-16598 CHEM ONLY

Click on a cross-section to see the sizes we stock:

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