Expansion K93603 / 4J28 Pipes Super Invar Alloy for Ultra Low Thermal Expansion and Precision Thermal Stability
Expansion K93603 / 4J28 Pipes are precision iron-nickel-cobalt alloy pipes engineered for applications where extremely low thermal expansion is critical. Known internationally as Super Invar Alloy, this material was developed to achieve significantly lower dimensional change than conventional Invar alloys during temperature fluctuations.
The addition of cobalt optimizes the crystal structure and reduces thermal expansion across a practical operating temperature range, making Expansion K93603 / 4J28 Pipes an ideal choice for precision engineering systems. These pipes are widely utilized in aerospace tooling, optical platforms, metrology equipment, semiconductor production systems, and scientific instrumentation where dimensional accuracy directly influences performance.
| Parameter | Value |
|---|---|
| Outside Diameter | 6 mm - 168 mm |
| Wall Thickness | 0.5 mm - 15 mm |
| Length | Up to 6000 mm |
| Surface | Bright Annealed, Pickled |
| Form | Seamless Pipe / Welded Pipe |
| Standards | ASTM F1684, UNS K93603, GB/T 15002 |
| Element | Content (%) |
|---|---|
| Nickel (Ni) | 31.5 - 33.0 |
| Cobalt (Co) | 4.0 - 6.0 |
| Iron (Fe) | Balance |
| Carbon (C) | ≤ 0.05 |
| Manganese (Mn) | ≤ 0.50 |
| Silicon (Si) | ≤ 0.30 |
| Phosphorus (P) | ≤ 0.02 |
| Sulfur (S) | ≤ 0.02 |
| Property | Value |
|---|---|
| Tensile Strength | ≥ 490 MPa |
| Yield Strength | ≥ 240 MPa |
| Elongation | ≥ 30% |
| Hardness | ≤ 160 HB |
| Property | Value |
|---|---|
| Density | 8.15 g/cm³ |
| Melting Range | 1425 - 1450°C |
| Thermal Conductivity | 13.5 W/m*K |
| Elastic Modulus | 141 GPa |
| Electrical Resistivity | 0.78 µΩ*m |
| Mean Coefficient of Thermal Expansion (20-100°C) | Approx. 0.6 × 10⁻⁶/K |
- Extremely low thermal expansion coefficient
- Excellent dimensional stability during temperature changes
- Suitable for ultra-precision engineering systems
- Good machinability and fabrication performance
- Reliable behavior under repeated thermal cycling
- Ideal for optical, aerospace, and metrology applications
Precision Measuring Equipment: Used in metrology frames, calibration systems, and coordinate measuring devices.
Aerospace Tooling: Applied in precision fixtures and thermal-stable aerospace structures.
Optical Systems: Suitable for telescope supports, laser equipment, and optical alignment assemblies.
Semiconductor Manufacturing: Used in wafer processing equipment and precision positioning systems.
Scientific Instrumentation: Applied in vacuum devices and laboratory equipment requiring dimensional stability.
Their ultra-low thermal expansion coefficient helps maintain dimensional accuracy under temperature variation.
Yes. UNS K93603 is internationally known as Super Invar Alloy and corresponds closely to Chinese grade 4J28.
They are widely used in aerospace, optics, semiconductor manufacturing, metrology, and scientific equipment.
Yes. The alloy offers good machinability for precision components and assemblies.
Because they minimize dimensional changes caused by temperature fluctuations, improving measurement accuracy.
- Surface: bright annealed, pickled
- Form: seamless pipe, welded pipe
- Packaging: moisture-proof wrapping with reinforced export wooden cases
Get in Touch
Have questions about our products or want to discuss a custom order? Our team is ready to help you.