INVAR 36

Type Analysis

Carbon: 0.15Max, Nickel: 36.0 nominal, Iron: Balance, Phosphorus: 0.006Max, Silicon: 0.40Max, Manganese: 0.60Max, Sulfur: 0.004Max, Chromium: 0.25Max, Cobalt: 0.50Max.

Description

Invar 36 is a 36% nickel-iron alloy possessing a rate of thermal expansion approximately one-tenth that of carbon steel at temperatures up to 400°F(204°C).

Applications

This alloy has been used for applications where dimensional changes due to temperature variation must be minimized such as in radio and electronic devices, aircraft controls, optical and laser system, etc.

Invar 36 alloy has also been used in conjunction with high expansion alloys in applications where a motion is desired when the temperature changes, such as in bimetallic thermostats and in rod and tube assemblies for temperature regulators.

Physical Properties

Specific gravity ................ 8.05

Density

lb/cu in ......................... 0.291

kg/cu m ......................... 8055

Thermal conductivity

Btu-in/ft²/hr/°F ................ 72.6

W/m þ K .......................... 10.5

Electrical resistivity

ohm-cir mil/ft ................... 495

microhm-mm ...................... 820

Temperature coefficient of electrical

resistivity

per °F (70/212°F) ............. 0.0006

per °C (21/100°C) ............. 0.0011