Invar 36,Nilo 36,UNS K93601,E FORU

### **Invar 36 / Nilo 36 / UNS K93601** **Iron-Nickel Low Expansion Alloy for Critical Dimensional Stability Applications** --- #### **1. Overview** **Nilo 36**, also known generically as **Invar 36**, is an iron-nickel alloy specifically engineered to exhibit an exceptionally low coefficient of thermal expansion (CTE) over a wide temperature range. This unique characteristic, stemming from its precise nickel content, makes it indispensable for applications requiring minimal dimensional changes with temperature fluctuations. Nilo 36 is particularly valued in aerospace, telecommunications, and precision instrumentation where thermal stability is paramount for performance and reliability. --- #### **2. Chemical Composition (Weight %)** The typical chemical composition of Nilo 36 is outlined below. The balance is Iron (Fe). | Element | Content (%) | Key Function | | :--- | :--- | :--- | | **Iron (Fe)** | Balance | Forms the fundamental matrix of the alloy. | | **Nickel (Ni)** | 35.0 - 37.0 | Critical element that enables the low thermal expansion characteristic through balanced electron band structure. | | **Manganese (Mn)** | 0.30 - 0.60 | Acts as a deoxidizer and enhances hot workability during manufacturing. | | **Silicon (Si)** | 0.20 - 0.35 | Improves casting characteristics and provides moderate oxidation resistance. | | **Carbon (C)** | 0.03 max | Kept at minimal levels to prevent aging effects and maintain long-term stability. | | **Cobalt (Co)** | 0.20 max | Controlled impurity to maintain consistent thermal properties. | | **Copper (Cu)** | 0.20 max | Controlled impurity. | | **Aluminum (Al)** | 0.10 max | Controlled to ensure consistent surface properties. | | **Chromium (Cr)** | 0.10 max | Controlled impurity. | | **Sulfur (S)** | 0.010 max | Kept at trace levels to prevent hot shortness during processing. | | **Phosphorus (P)** | 0.010 max | Minimized to maintain ductility and workability. | --- #### **3. Physical Properties** | Property | Value / Condition | | :--- | :--- | | **Density** | 8.12 g/cm³ (0.293 lb/in³) | | **Melting Range** | ~ 1425 - 1430 °C (2597 - 2606 °F) | | **Mean Coefficient of Thermal Expansion** | 20 - 100°C (68 - 212°F): **1.2 x 10⁻⁶/°C** (0.67 x 10⁻⁶/°F)
20 - 200°C (68 - 392°F): **2.5 x 10⁻⁶/°C** (1.39 x 10⁻⁶/°F)
20 - 300°C (68 - 572°F): **4.7 x 10⁻⁶/°C** (2.61 x 10⁻⁶/°F) | | **Thermal Conductivity** | 10.8 W/m·K (75 Btu·in/hr·ft²·°F) at 20°C (68°F) | | **Specific Heat Capacity** | 520 J/kg·K (0.124 Btu/lb·°F) at 20°C (68°F) | | **Electrical Resistivity** | 0.80 μΩ·m at 20°C (68°F) | | **Modulus of Elasticity (Young's Modulus)** | 142 GPa (20.6 x 10⁶ psi) at 20°C (68°F) | | **Curie Temperature** | ~ 280 °C (536 °F) | | **Magnetic Permeability** | Ferromagnetic below Curie temperature | --- #### **4. Mechanical Properties (Typical for Annealed Condition)** | Property | Value at Room Temperature | | :--- | :--- | | **Tensile Strength** | 460 MPa (67 ksi) | | **Yield Strength (0.2% Offset)** | 290 MPa (42 ksi) | | **Elongation (in 50 mm / 2 in)** | 36% | | **Reduction of Area** | 72% | | **Hardness (Rockwell B)** | 72 HRB | | **Vickers Hardness** | 145 HV | --- #### **5. International Standards** Nilo 36 conforms to the following international specifications: * **ASTM:** * **F1684:** Standard Specification for Iron-Nickel and Iron-Nickel-Cobalt Alloys for Low Thermal Expansion Applications * **AMS:** * **AMS 7725:** Sheet, Strip, and Plate * **UNS:** K93601 * **ISO:** * **ISO 19960:** Iron-nickel low expansion alloys * **EN:** * **EN 10140:** Cold rolled narrow steel strip * **MIL:** * **MIL-I-23011:** Insulating Compound, Electrical (for Sealing Applications) --- #### **6. Product Applications** Nilo 36 is essential in applications requiring exceptional dimensional stability: * **Aerospace & Satellite Systems:** * Satellite structural frames and supports * Optical bench structures * Antenna deployment mechanisms * Space telescope components * **Precision Instrumentation:** * Laser housing and mounting systems * Interferometer components * Surveying equipment frames * Laboratory standard devices * **Telecommunications:** * Microwave cavity resonators * Waveguide components * Filter structures * Base station antenna elements * **Semiconductor Manufacturing:** * Photolithography mask frames * Wafer handling equipment * Precision stage components * **Energy & Cryogenics:** * LNG storage tank inner walls * Cryogenic piping systems * Superconducting magnet supports --- #### **7. Key Characteristics & Advantages** * **Ultra-Low Thermal Expansion:** Exceptional dimensional stability with CTE as low as 1.2 x 10⁻⁶/°C * **Excellent Thermal Stability:** Maintains properties across wide temperature ranges * **Superior Cryogenic Performance:** Reliable performance down to cryogenic temperatures * **Good Mechanical Properties:** Balanced strength and ductility for structural applications * **Excellent Fabricability:** Can be readily machined, welded, and formed using standard methods * **Predictable Material Behavior:** Well-established properties for reliable engineering design * **Long-Term Stability:** Minimal aging effects for sustained performance over time * **Proven Track Record:** Extensive successful applications in demanding environments --- **Disclaimer:** *Nilo® is a registered trademark. The values provided are typical and for informational purposes only. For critical applications, always consult the official material data sheets from the supplier and relevant design codes. Proper stress relief treatments may be required for optimal dimensional stability in precision applications.*

Packing of Standard Packing: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 1682 gallon liquid totes Special package is available on request.