Invar 42

Principal Design Features

This is an iron-nickel alloy with controlled thermal expansion properties.


Used for glass-to-metal sealing of components that are enclosed in a glass envelope, such as lamps and electron tubes.


The alloy is readily machinable by conventional techniques.


Ductility and thus formability are very good.


The alloy may be welded by conventional methods.

Heat Treatment

An annealing heat treatment may be used. The alloy is not hardenable by heat treatment.


Forging may be done at 2200 F. As is true of all the high nickel content alloys care should be taken to avoid contamination from sulfur due to long soaking time in a furnace atmosphere.

Cold Working

The alloy has good ductility and is readily cold worked.


Anneal at 1450F (788C) followed by air cooling.


Hardens due to cold working only.

Density: 0.293

Specific Gravity: 8.12

Specific Heat: 0.12

Electrical Resistivity: 494

Melting Point: 2600

MCTE: 0.8

MoETensile: 21.5


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