Invar 36,Alloy 36 Fittings,UNS K93600,E FORU

British Specs:，American Specs: ASTM F1684 MIL-S-16598 Tooling plate ASTM B388 Sheet & strip ASTM B753 K93050 Free-cut Invar，German Specs:WS 1.3912

### **Invar 36 / Alloy 36 Fittings (UNS K93600) - Product Introduction** #### **Overview** Invar 36, also known as Alloy 36 or UNS K93600, is a nickel-iron alloy renowned for its exceptionally low Coefficient of Thermal Expansion (CTE). **Alloy 36 Fittings** are precision-engineered components, such as flanges, couplings, elbows, and ferrules, designed for use in piping and tubing systems where extreme dimensional stability under temperature fluctuations is critical. These fittings are essential for maintaining structural integrity and alignment in systems operating from cryogenic temperatures up to approximately 300°C (570°F). #### **Key Characteristics of Alloy 36 Fittings** * **Exceptional Dimensional Stability:** The CTE is typically about **1.6 x 10⁻⁶/°C** between 20°C and 100°C, making the fittings virtually immune to thermal expansion and contraction. * **High Strength and Toughness:** Maintains good mechanical properties across a wide temperature range, ensuring leak-proof and reliable connections. * **Excellent Weldability:** Fittings can be readily welded to matching Alloy 36 pipes or other components using common techniques like TIG and Electron Beam welding. * **Compatibility with Cryogenic and Elevated Temperatures:** Performs reliably in applications ranging from LNG temperatures (-162°C) to moderate heat. --- #### **1. Chemical Composition** The unique properties of Invar 36 are achieved through a tightly controlled chemical composition. | Element | Content (%) | | :--- | :--- | | **Nickel (Ni)** | 36.0% min | | **Iron (Fe)** | Balance | | **Carbon (C)** | 0.10% max | | **Manganese (Mn)** | 0.60% max | | **Silicon (Si)** | 0.40% max | | **Phosphorus (P)** | 0.025% max | | **Sulfur (S)** | 0.025% max | | **Cobalt (Co)** | 0.50% max | | **Chromium (Cr)** | 0.25% max | --- #### **2. Physical Properties** | Property | Value / Description | | :--- | :--- | | **Density** | 8.11 g/cm³ (0.293 lb/in³) | | **Melting Point** | ~1427°C (2600°F) | | **Thermal Expansion Coefficient (CTE)** | **1.6 x 10⁻⁶/°C** (20-100°C)
2.7 x 10⁻⁶/°C (20-300°C) | | **Thermal Conductivity** | 10.5 W/m·K (at 20°C) | | **Specific Heat** | 515 J/kg·K (at 20°C) | | **Magnetic Properties** | Ferromagnetic at room temperature. Becomes non-magnetic (paramagnetic) above its Curie temperature of ~279°C (534°F). | --- #### **3. Typical Mechanical Properties (Annealed)** *Properties are typical for finished, annealed fittings to ensure machinability and stress-relief.* | Property | Value | | :--- | :--- | | **Tensile Strength** | 517 MPa (75 ksi) | | **Yield Strength (0.2% Offset)** | 276 MPa (40 ksi) | | **Elongation (in 2")** | 30% | | **Hardness (Rockwell B)** | ~75 HRB | | **Modulus of Elasticity** | 141 GPa (20.5 x 10⁶ psi) | --- #### **4. Product Applications** Alloy 36 Fittings are used in critical systems where thermal mismatch between components would cause failure. * **Cryogenic Systems:** * **LNG (Liquefied Natural Gas) Systems:** Fittings for transfer lines, storage tank connections, and instrumentation lines. Their stability prevents leaks at -162°C. * **Scientific Cryostats:** Connections and ferrules for systems containing liquid helium, hydrogen, or nitrogen. * **Aerospace & Aviation:** * **Fuel and Hydraulic Lines:** In high-performance aircraft and spacecraft where systems experience wide temperature swings. * **Sensor and Instrumentation Mounting:** Ensuring the precise alignment of critical sensors regardless of ambient temperature changes. * **Semiconductor Manufacturing:** * **Ultra-Pure Gas and Chemical Delivery Systems:** Fittings used in gas panels and distribution lines where purity and stability are paramount to prevent particle generation. * **Power Generation:** * **Seals and Connectors:** In power turbines and nuclear instrumentation systems, where reliable performance under thermal cycling is required. * **Precision Optical Systems:** * **Vacuum Chamber Feedthroughs:** Mounting and connection fittings for optical components inside chambers, maintaining alignment between the internal and external structures. --- #### **5. International Standards** While specific fitting standards for Alloy 36 are less common than for plate/sheet, the material is governed by several international standards, and fittings are often manufactured to customer prints or applicable generic standards. | Standard Body | Standard Designation | Title / Scope | | :--- | :--- | :--- | | **UNS** | **K93600** | Unified Numbering System | | **ASTM** | **ASTM F1684** | Standard Specification for Iron-Nickel and Cobalt-Nickel Alloy Sheet, Strip, and Plate *(Covers the base material)* | | **AMS** | **AMS 7725** | Alloy 36, Sheet, Strip, and Plate (Aerospace Material Specification) | | **EN / Euronorm** | **EN 1.3912 / Ni36** | Wrought Steel Products | | **DIN** | **DIN 1.3912 / Ni36** | German Institute for Standardization | | **ASME** | **SB-753 / SB-754** | Specification for Nickel-Iron-Chromium Alloy Seamless Pipe and Tube / Fittings (While for different alloys, this is the performance-based framework often referenced). | *Note: Alloy 36 Fittings are often **custom-manufactured components**. The procurement typically relies on the **ASTM F1684** or **AMS 7725** material specification, with the dimensional and tolerancing requirements defined by customer engineering drawings.* --- #### **Conclusion** Invar 36 (Alloy 36) Fittings, UNS K93600, are critical components for engineers designing systems that must remain dimensionally stable under severe thermal cycling. Their ability to connect pipes and tubes without introducing thermal stress makes them indispensable in cryogenics, aerospace, and high-precision industries. When sourcing these fittings, it is crucial to specify the required material certification (e.g., to ASTM F1684) and the precise dimensional tolerances to ensure system integrity and performance.

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 2399 gallon liquid totes Special package is available on request.