4J32 Super-Invar Alloy Specification
Ultra-Low Expansion Fe-Ni-Co Alloy for Precision Applications
Product Specification
| Standard | GB/T 15018 (China), ASTM F1684 (USA) |
| Material Designation | 4J32 (Fe-Ni-Co), Super-Invar |
| Tolerance | h7-h11 (on request) |
| Melt Method | Vacuum Induction Melting (VIM) |
| Available Forms & Sizes | Plate: 0.1mm – 100mm thick Bar: Φ3mm – Φ250mm Wire: Φ0.05mm – Φ5.0mm Custom profiles upon request |
Chemical Composition (wt%)
| Element | Min (%) | Max (%) |
| Nickel (Ni) | 31.5 | 33.5 |
| Cobalt (Co) | 3.2 | 4.2 |
| Iron (Fe) | Balance | |
| Manganese (Mn) | 0.20 | 0.60 |
| Copper (Cu) | 0.40 | 0.80 |
| Carbon (C) | – | 0.05 |
| Silicon (Si) | – | 0.30 |
| Phosphorus (P) | – | 0.02 |
| Sulfur (S) | – | 0.02 |
Thermal Expansion Properties
| Temperature Range (°C) | Average CTE (×10⁻⁶/°C) | Matching Materials |
| 20 – 100 | 0.8 – 1.8 | Hard glasses, Silicon |
| 20 – 300 | ≈6.6 | DM-308 Glass |
| 20 – 400 | ≈7.2 | Corning 7052 Glass |
| -60 – 80 | Lower than 4J36 | Optical ceramics |
Mechanical Properties (Annealed Condition)
- Tensile Strength: 440-590 MPa
- Yield Strength: 280-390 MPa
- Elongation: ≥25-30%
- Hardness: 135-185 HB
- Elastic Modulus: ≈145 GPa
Applications
- Satellite structural components and optical mounts
- Semiconductor packaging and chip carriers
- Laser alignment systems and interferometer frames
- Microwave tube components and vacuum electronic devices
- Cryogenic equipment for LNG applications
- Precision measurement instruments and standards
Special Processing Notes
- Recommended heat treatment: 840°C±10°C/1h water quench + 315°C±10°C/1h furnace cool
- Avoid slow cooling in 300-550°C range to prevent phase transformation
- Welding: Use TIG or electron beam welding with matching filler material
- Store in dry environment to prevent surface oxidation
