Alloy 42,Low expansion 42 Alloy ,UNS K94100,E FORU

British Specs:，American Specs: ASTM F30 ASTM B 753 AMS 5683 Welding Wire，German Specs: WS 1.3917,DIN 17745 AFNOR NF A54-301

**PRODUCT DATASHEET: ALLOY 42 / LOW EXPANSION 42 ALLOY** **UNS K94100 - Controlled Expansion Nickel-Iron Alloy** --- ### **1. OVERVIEW** **Alloy 42**, also commercially known as **Low Expansion 42 Alloy**, is a precision **nickel-iron alloy** containing **42% nickel** that exhibits a uniquely **low coefficient of thermal expansion (CTE)** closely matching those of **borosilicate glass, alumina ceramics, and semiconductor materials**. This controlled expansion characteristic makes it indispensable for applications requiring dimensional stability across temperature variations. The alloy is registered under the Unified Numbering System as **UNS K94100**. --- ### **2. CHEMICAL COMPOSITION (Weight %)** | Element | Alloy 42 Specification | UNS K94100 Requirements | |------------------|------------------------|-------------------------| | **Nickel (Ni)** | 41.0 – 42.5% | 41.0 – 42.5% | | **Iron (Fe)** | Balance | Balance | | **Manganese (Mn)**| 0.50 – 0.80% | ≤ 0.80% | | **Silicon (Si)** | 0.15 – 0.30% | ≤ 0.30% | | **Carbon (C)** | ≤ 0.05% | ≤ 0.05% | | **Chromium (Cr)**| ≤ 0.15% | ≤ 0.15% | | **Copper (Cu)** | ≤ 0.05% | ≤ 0.05% | | **Aluminum (Al)**| ≤ 0.05% | ≤ 0.05% | | **Sulfur (S)** | ≤ 0.015% | ≤ 0.015% | | **Phosphorus (P)**| ≤ 0.015% | ≤ 0.015% | --- ### **3. PHYSICAL & MECHANICAL PROPERTIES** | Property | Typical Value (Annealed Condition) | |---------------------------------|-----------------------------------| | **Coefficient of Thermal Expansion** | 4.5 – 5.5 × 10⁻⁶/°C (20–300°C) | | **Density** | 8.11 g/cm³ | | **Melting Point** | 1420 – 1450°C | | **Tensile Strength** | 520 – 620 MPa | | **Yield Strength (0.2% Offset)**| 280 – 380 MPa | | **Elongation (in 2")** | 30 – 40% | | **Modulus of Elasticity** | 145 GPa | | **Hardness (Rockwell B)** | 65 – 80 HRB | | **Electrical Resistivity** | 0.75 μΩ·m | | **Thermal Conductivity** | 14.5 W/m·K | | **Curie Temperature** | 360°C | | **Magnetic Permeability** | < 100 (at 200 Oe) | --- ### **4. INTERNATIONAL STANDARDS & EQUIVALENTS** | Standard Organization | Designation & Specification | |-----------------------|----------------------------| | **UNS** | K94100 | | **ASTM** | F30 (Alloy 42) | | **ASTM Alternative** | A658 / F2543 | | **EN (European)** | 1.3917 (Ni42Fe) | | **ISO** | NiFe42 | | **JIS (Japan)** | C42N | | **GB (China)** | 4J42 | | **DIN (Germany)** | Ni42 | --- ### **5. THERMAL EXPANSION CHARACTERISTICS** #### **CTE vs Temperature Range** - **20–100°C**: 4.8 × 10⁻⁶/°C - **20–200°C**: 5.2 × 10⁻⁶/°C - **20–300°C**: 5.5 × 10⁻⁶/°C - **20–400°C**: 7.8 × 10⁻⁶/°C #### **CTE Matching Compatibility** - **Borosilicate Glass**: Excellent match (3.3 × 10⁻⁶/°C) - **Alumina Ceramic (96%)**: Very good match (6.5–7.5 × 10⁻⁶/°C) - **Silicon Semiconductor**: Good match (2.6–4.2 × 10⁻⁶/°C) - **Gallium Arsenide**: Acceptable match (5.7–6.9 × 10⁻⁶/°C) --- ### **6. PRODUCT APPLICATIONS** #### **6.1 Electronics & Semiconductor Packaging** - **Lead Frames**: Integrated circuits, transistors, diodes - **Semiconductor Bases**: Power device substrates, chip carriers - **Hybrid Circuits**: Thick-film and thin-film circuit bases - **Electronic Packages**: Hermetic and ceramic packages #### **6.2 Glass-to-Metal Sealing** - **Hermetic Seals**: Connectors, sensors, relays, switches - **Feedthroughs**: Electrical and optical feedthrough components - **Enclosure Seals**: Military, aerospace, and medical enclosures - **Optical Seals**: Laser and optical package sealing #### **6.3 Precision Instruments** - **Measuring Equipment**: Precision scales, rulers, standards - **Optical Instruments**: Telescope mounts, mirror supports - **Laboratory Apparatus**: Scientific instrument frames - **Metrology Equipment**: Coordinate measuring machine components #### **6.4 Automotive & Aerospace** - **Sensor Housings**: Temperature and pressure sensor components - **Control Systems**: Avionics and engine control mounts - **Communication Systems**: RF and microwave package bases - **Navigation Equipment**: Gyroscope and accelerometer frames #### **6.5 Special Applications** - **Cryogenic Equipment**: Support structures for low-temperature use - **Bimetal Thermostats**: Low-expansion side of bimetal strips - **Mold Bases**: Composite curing tools and molds - **Laser Systems**: Optical benches and mounting components --- ### **7. AVAILABLE PRODUCT FORMS** - **Sheet & Strip**: 0.05 mm to 6.0 mm thickness - **Plate**: 6.0 mm to 100 mm thickness - **Wire**: 0.05 mm to 6.0 mm diameter - **Rod & Bar**: 3.0 mm to 150 mm diameter - **Tube & Pipe**: Seamless and welded configurations - **Forgings**: Custom forged components - **Custom Shapes**: Precision stamped and formed parts --- ### **8. FABRICATION CHARACTERISTICS** #### **8.1 Machining** - **Machinability**: 20% (compared to free-cutting brass at 100%) - **Recommended Tools**: Carbide or high-speed steel with positive rake - **Cutting Speed**: Moderate with adequate cooling - **Surface Finish**: Good with proper techniques #### **8.2 Forming** - **Deep Drawing**: Excellent in annealed condition - **Bend Radius**: Minimum 1× material thickness - **Springback**: Predictable and consistent - **Work Hardening**: Moderate rate, may require intermediate annealing #### **8.3 Joining** - **Welding**: TIG, MIG, resistance welding compatible - **Brazing**: Excellent with silver-based brazing alloys - **Soldering**: Good with proper flux and techniques - **Adhesive Bonding**: Suitable with surface preparation #### **8.4 Heat Treatment** - **Annealing**: 750–850°C followed by rapid cooling - **Stress Relieving**: 500–600°C for 1–2 hours - **Atmosphere**: Hydrogen or vacuum recommended for bright annealing - **Grain Size**: Controlled to ASTM 5–8 for optimal properties --- ### **9. QUALITY ASSURANCE & CERTIFICATION** - **Material Certification**: EN 10204 3.1/3.2 - **Chemical Analysis**: Certified spectrographic analysis - **Mechanical Testing**: Tensile, hardness, and elongation verification - **Dimensional Inspection**: Per applicable standards - **CTE Verification**: Precision dilatometer testing available - **Traceability**: Full material history from melt to final product --- ### **10. TECHNICAL ADVANTAGES** - **Controlled Thermal Expansion**: Precise CTE matching for reliable performance - **Excellent Sealing Characteristics**: Perfect for glass and ceramic sealing applications - **Good Corrosion Resistance**: Suitable for most industrial environments - **High Strength-to-Weight Ratio**: Robust performance in lightweight applications - **Stable Magnetic Properties**: Low permeability and minimal magnetostriction - **Proven Reliability**: Long-term performance in critical applications --- **Note:** The thermal expansion characteristics of Alloy 42 are heat treatment sensitive. Proper thermal processing is essential to achieve the specified CTE values. Consultation with our technical team is recommended for critical applications requiring precise thermal expansion control or specialized processing.

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 2456 gallon liquid totes Special package is available on request.