# 4J36

> Invar 36 — Fe-Ni alloy with near-zero thermal expansion for precision instruments and cryogenic service.

4J36 (Invar 36) is an iron-nickel alloy exhibiting exceptionally low thermal expansion coefficient (≈1.3 × 10⁻⁶/°C) from cryogenic temperatures to 230°C. It is the essential material for precision instrument components, optical benches, LNG tank membranes and composite tooling where dimensional stability under temperature variation is critical.

## Key features

- Near-zero thermal expansion (α ≈ 1.3 × 10⁻⁶/°C)
- Invar 36 standard
- Cryogenic to 230°C range
- Dimensional stability champion
- LNG tank membrane material

## Applications

- Precision optical benches and mounts
- LNG carrier tank membranes
- Composite material tooling
- Laser and optical cavities
- Cryogenic transfer line components

## Standards

- ASTM F1684
- GB/T 14986
- AFNOR NF A54-301