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Invar 36 wire, made from a nickel-iron alloy containing approximately 36% nickel, is renowned for its uniquely low coefficient of thermal expansion. This property makes the wire ideal for applications where dimensional stability is critical over a wide range of temperatures. Industries such as aerospace, electronics, cryogenics, and telecommunications rely heavily on Invar 36 wire for components requiring extreme precision. Its ability to maintain size under thermal fluctuations sets it apart from other metal wires.
Chemical Composition of Invar 36 Wire
The wire retains the same chemical structure as other Invar 36 products to ensure consistent performance across applications:
| Element | Content (%) |
|---|---|
| Nickel (Ni) | 35.0 – 37.0 |
| Iron (Fe) | Balance |
| Carbon (C) | ≤ 0.05 |
| Silicon (Si) | ≤ 0.35 |
| Manganese (Mn) | ≤ 0.60 |
| Sulfur (S) | ≤ 0.02 |
| Phosphorus (P) | ≤ 0.02 |
Key Properties of Invar 36 Wire
Invar 36 wire stands out for its stability and strength across varied conditions:
| Property | Typical Value |
|---|---|
| Density | 8.1 g/cm³ |
| Melting Point | 1430°C (2606°F) |
| Thermal Expansion (20–100°C) | ~1.2 × 10⁻⁶ /°C |
| Tensile Strength | 485–620 MPa |
| Yield Strength | 240–450 MPa |
| Modulus of Elasticity | 140 GPa |
| Electrical Resistivity | 0.78 μΩ·m |
Available Forms and Sizes
Invar 36 wire is produced in various diameters and formats to support industrial and precision applications:
| Diameter (mm) | Common Applications |
|---|---|
| 0.05 – 0.2 | Thermal sensors, scientific instruments |
| 0.2 – 0.5 | Electrical components, connectors |
| 0.5 – 1.0 | Lead wires, support structures |
| 1.0 – 3.0 | Springs, tension wires |
Applications of Invar 36 Wire
The wire is valued in high-precision applications requiring dimensional stability over temperature changes:
| Industry | Application |
|---|---|
| Electronics | Shadow masks, CRT supports |
| Aerospace | Satellite wiring, thermal shunts |
| Medical | Implants, surgical instrumentation |
| Cryogenics | Low-temperature sensor leads |
| Telecommunications | Waveguide stabilizers, antenna components |
Standards and Designations
Invar 36 wire meets global specifications ensuring quality and reliability:
| Standard | Description |
|---|---|
| UNS | K93600 |
| ASTM | B268, F1684 |
| ISO | 6208, 10003 |
| AMS | I23011, 2241 |
Machining and Handling Notes
Because of its low thermal expansion, Invar 36 wire must be handled carefully to maintain properties:
| Operation | Guidance |
|---|---|
| Cutting | Use sharp tools; avoid excess heat |
| Bending | Moderate flexibility; anneal before tight bends |
| Welding | Use matching Invar 36 filler metal for joints |
| Cleaning | Non-corrosive cleaning agents only |
Packaging and Supply Formats
Manufacturers provide Invar 36 wire in convenient packaging tailored to various production needs:
| Format | Packaging Description |
|---|---|
| Coil | Spiral-wound on plastic or metal reels |
| Spool | Precision wound for automated feed systems |
| Straight Cut | Fixed-length rods for manual use |
Related Questions
What is Invar 36 wire used for?
Invar 36 wire is used in applications requiring low thermal expansion such as electronics, aerospace wiring, cryogenic systems, and optical instruments.
Is Invar 36 wire corrosion-resistant?
While Invar 36 has moderate corrosion resistance, it is not as corrosion-resistant as stainless steel and may require surface protection in humid or marine environments.
Can Invar 36 wire be soldered?
Yes, Invar 36 wire can be soldered, but care must be taken to use compatible fluxes and maintain proper joint temperature to prevent distortion and ensure bonding strength.