Invar 36

Principal Design Features

This is one of the controlled expansion alloys. It has an expansion rate roughly 10 % that of standard carbon steels. Also known as Invar 36 or Alloy 36, the only alloy with lower CTE is Super Invar, or Alloy 32-6, but this alloy is extremely rare and is generally only produced by the mill in heat lot quantities. Note: Recent testing has determined that increased hardness will decrease CTE in all temperature ranges in Invar alloys.


Commonly employed in electronic equipment such as radios, laser systems and thermostats.


This alloy can be machined employing most common methods. It is known to produce “gummy” chips and is best machined at slow speeds with positive and constant feeds.


The alloy is readily formed using most common practices and should not present any unusual problems. For maximum properties, material should be fully annealed after any forming operations.


All common joining techniques can be successfully employed here. When a filler metal is required, it is suggested to use a similar composition alloy, available from the manufacturer.


Heat to 2150 F(1180 C) rapidly and cool rapidly following working. Do not soak at temperature.

Cold Working

This alloy can be cold upset and swaged successfully.


Hold at 1450 F(790 C) 30 minutes for every inch of thickness, followed by air cooling. To obtain maximum dimensional stability, soak at 1500 F(815 C) and water quench. Reheat to 600 F(315 C) for 1 hour and air cool.


This alloy will not respond to hardening by thermal treatment.

Density: 0.293

Specific Gravity: 8.11

Specific Heat: 0.12

Electrical Resistivity: 495

Melting Point: 2600

MoETensile: 21


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