Invar 36

Invar 36 is a nickel-iron, low-expansion alloy containing 36% nickel. It maintains nearly constant dimensions over the range of normal atmospheric temperatures and has a low coefficient of expansion from cryogenic temperatures to about 500°F. The alloy also retains good strength and toughness at cryogenic temperatures. Invar 36 can be hot and cold formed and machined using processes similar to austenitic stainless steels. Invar 36 is weldable using Filler Metal CF36 which is available in bare wire for both the GTAW and GMAW process.

Invar 36 alloy is available in two variations. The first is the conventional Invar alloy, typically used for its optimum low expansion properties. The second is a variation of the basic alloy known as “Free-Cut” or “Free-Machining” (UNS K93050 and ASTM F1684). This alloy has shown improved machinability for applications where high productivity is important. It is the same 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 Invar 36FM (Free Machining)

Free-Machining Variation:
Invar 36FM alloy, the world’s first free-machining Invar alloy, is typically used by machine shops that produce high volumes of parts such as hot water heater controls, filters for microwave instruments and precision parts for optical mounting in lenses.