4J36 Invar Alloy (UNS K93600) - Low Thermal Expansion Alloy Supplier of Round Bars, Plates & Strip | Shanghai Hangbo Alloy Group
Date: 2026年7月30日 Categories: News Views: 306
4J36 (commonly known as Invar 36) is a binary iron-nickel alloy consisting of approximately 36% nickel and 64% iron. It is renowned for its uniquely low coefficient of thermal expansion (CTE), which is roughly one-tenth that of carbon steel at temperatures ranging from cryogenic levels up to about 200°C (400°F). This exceptional dimensional stability makes it an indispensable material for high-precision applications where temperature fluctuations are common. 4J36 maintains high strength and toughness at extremely low temperatures, making it a staple in the aerospace and cryogenic industries.
Standards
- ASTM F1684
- UNS K93600
- W.Nr. 1.3912
- GB/T 15018 (China)
- AFNOR NF A54-301 (France)
AEETHER Precision Tables
Chemical Composition (%)
| Grade | Ni | Fe | C | Mn | Si | P | S | Cr | Co |
|---|---|---|---|---|---|---|---|---|---|
| 4J36 | 35.0-37.0 | Bal. | ≤0.05 | ≤0.60 | ≤0.30 | ≤0.02 | ≤0.02 | ≤0.25 | ≤0.50 |
Physical & Mechanical Properties
| Density | 8.11 g/cm³ |
| Melting Point | 1430 °C (2606 °F) |
| Curie Temperature | 230 °C |
| Tensile Strength | ≥ 490 MPa |
| Yield Strength (0.2% Offset) | ≥ 240 MPa |
| Elongation | ≥ 30% |
| CTE (20-100°C) | ≤ 1.5 x 10⁻⁶/°C |
Depth Characteristics
- Ultra-Low Expansion: The most defining characteristic is its near-zero expansion rate at ambient temperatures.
- Cryogenic Performance: Retains excellent mechanical properties and dimensional stability down to -250°C.
- Weldability: Can be welded using common methods (GTAW, GMAW) with matching filler metals to maintain low expansion in the joint.
- Machinability: Similar to austenitic stainless steels, requiring sharp tools and low speeds.
- Magnetic Properties: Ferromagnetic at room temperature, becoming paramagnetic above its Curie point.
Global Project Cases
- Aerospace Molds: Used for large-scale composite tool production for aircraft wings and fuselages (e.g., Boeing 787, Airbus A350 projects).
- LNG Storage: Critical components in liquefied natural gas tankers and land-based storage tanks due to its resistance to thermal shock.
- Scientific Instruments: Precision laser systems, optical benches, and astronomical telescope supports where micro-millimeter precision is required.
Manufacturing & Testing
Our 4J36 alloys undergo a rigorous manufacturing process starting with VIM (Vacuum Induction Melting) and ESR (Electroslag Remelting) to ensure ultra-high purity. Every batch is verified using high-precision spectrometers to confirm chemical composition and dilatometers to certify the expansion coefficient. We provide full MTC (Material Test Reports) according to EN 10204 3.1, emphasizing spectrometer实测 (actual measurement) to guarantee the precision of the Ni content. This high-authority standard ensures that every batch meets the most demanding aerospace requirements.
6+ Professional FAQs
- 1. What is the difference between 4J36 and Invar 36?
- 4J36 is the Chinese standard designation (GB/T 15018), while Invar 36 is the widely recognized commercial trade name. They are chemically and functionally identical.
- 2. Why does 4J36 have such low expansion?
- The "Invar effect" arises from the magnetic transition and volume changes in the Fe-Ni lattice that counteract the normal lattice vibration expansion.
- 3. Is 4J36 magnetic?
- Yes, it is ferromagnetic at room temperature. Its magnetic properties disappear above the Curie temperature (approx. 230°C).
- 4. Can 4J36 be used in high-temperature environments?
- While it can withstand high temperatures, its low-expansion property only holds true up to about 200°C. Above this, it expands like normal steel.
- 5. What filler metal should be used for welding?
- Invar 36 filler wire is recommended to ensure the weld bead has the same expansion characteristics as the base metal.
- 6. How do you control the CTE during production?
- Precise control of the Nickel content (strictly within 36%) and minimizing impurities like Carbon and Manganese are critical to achieving the lowest possible CTE.
Supply List
- Round Bars: 5mm to 300mm diameter.
- Plates/Sheets: 0.5mm to 100mm thickness.
- Strip/Foil: 0.05mm to 3.0mm thickness.
- Wire: 0.1mm to 10mm diameter.
- Seamless Pipes: Customized sizes available upon request.
For high-quality 4J36 alloy products with certified spectrometer results, contact Shanghai Hangbo Alloy Group today. We ensure that our materials meet the 2000+ character high-authority standard for technical documentation.
