Alloy 42,Low expansion 42 Alloy Bar(Round bar, Flat bar),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 BAR** **UNS K94100 - Round Bar & Flat Bar Products** --- ### **1. OVERVIEW** **Alloy 42**, commercially known as **Low Expansion 42 Alloy**, is a specialized **nickel-iron alloy** containing precisely **42% nickel** that exhibits an exceptionally **low coefficient of thermal expansion (CTE)**, carefully engineered to match **borosilicate glass, alumina ceramics, and semiconductor materials**. Supplied in both **round bar and flat bar** forms, this material provides excellent machinability and dimensional stability for precision components operating in thermally variable environments. The alloy is registered under the Unified Numbering System as **UNS K94100**. --- ### **2. CHEMICAL COMPOSITION (Weight %)** | Element | Alloy 42 Bar 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 | Round Bar (Annealed) | Flat Bar (Annealed) | |---------------------------------|----------------------|-----------------------| | **CTE (20–300°C)** | 4.5 – 5.5 × 10⁻⁶/°C | 4.5 – 5.5 × 10⁻⁶/°C | | **Density** | 8.11 g/cm³ | 8.11 g/cm³ | | **Melting Point** | 1420 – 1450°C | 1420 – 1450°C | | **Tensile Strength** | 520 – 620 MPa | 540 – 640 MPa | | **Yield Strength (0.2% Offset)**| 280 – 380 MPa | 300 – 400 MPa | | **Elongation (in 2")** | 30 – 40% | 25 – 35% | | **Modulus of Elasticity** | 145 GPa | 145 GPa | | **Hardness (Rockwell B)** | 65 – 80 HRB | 70 – 85 HRB | | **Electrical Resistivity** | 0.75 μΩ·m | 0.75 μΩ·m | | **Thermal Conductivity** | 14.5 W/m·K | 14.5 W/m·K | | **Magnetic Permeability** | < 100 (200 Oe) | < 100 (200 Oe) | --- ### **4. INTERNATIONAL STANDARDS & EQUIVALENTS** | Standard Organization | Designation & Specification | |-----------------------|----------------------------| | **UNS** | K94100 | | **ASTM** | F30 (Alloy 42) | | **EN (European)** | 1.3917 (Ni42Fe) | | **ISO** | NiFe42 | | **JIS (Japan)** | C42N | | **GB (China)** | 4J42 | | **DIN (Germany)** | Ni42 | | **Bar Standards** | ASTM A276, AMS 7721 | --- ### **5. PRODUCT SPECIFICATIONS** #### **5.1 Round Bar Specifications** - **Diameter Range**: 3.0 mm to 200 mm - **Diameter Tolerance**: h9 (±0.025 mm to ±0.115 mm) - **Straightness**: 0.5 mm per 300 mm maximum - **Surface Finish**: Hot-rolled, cold-drawn, or turned - **Standard Lengths**: 3.0 m, 3.66 m, 4.0 m, 6.0 m #### **5.2 Flat Bar Specifications** - **Thickness Range**: 3.0 mm to 100 mm - **Width Range**: 10 mm to 300 mm - **Thickness Tolerance**: ±0.15 mm to ±0.80 mm - **Width Tolerance**: ±0.5 mm to ±2.0 mm - **Squareness**: 0.5° maximum deviation #### **5.3 Available Conditions** - **Hot-Rolled**: As-rolled with scale, annealed - **Cold-Drawn**: Smooth finish, close tolerances - **Annealed**: Soft condition for machining - **Stress-Relieved**: For dimensional stability --- ### **6. PRODUCT APPLICATIONS** #### **6.1 Round Bar Applications** - **Precision Shafts**: Optical and electronic equipment shafts - **Machined Pins**: Connector pins and alignment dowels - **Sealing Studs**: Glass-to-metal seal components - **Support Rods**: Instrument frame and structural supports - **Tooling Components**: Jig and fixture elements #### **6.2 Flat Bar Applications** - **Mounting Brackets**: Electronic and optical mounting brackets - **Structural Frames**: Instrument chassis and framework - **Base Plates**: Precision equipment base components - **Heat Sink Bases**: Thermal management substrates - **Spacer Bars**: Precision spacing and shimming elements #### **6.3 Electronics & Semiconductor** - **Lead Frame Bases**: Integrated circuit lead frame substrates - **Semiconductor Tooling**: Wafer handling component stock - **Vacuum Components**: Chamber structural elements - **Chip Carrier Frames**: Microelectronic package frames #### **6.4 Precision Instruments** - **Measuring Equipment**: Precision scale and ruler stock - **Optical Mounts**: Telescope and laser mounting components - **Laboratory Apparatus**: Scientific instrument structural parts - **Alignment Elements**: Precision straight edges and guides --- ### **7. MACHINING & FABRICATION** #### **7.1 Machinability** - **Machinability Rating**: 25% (relative to 1212 steel) - **Recommended Tools**: Carbide or high-speed steel with positive rake - **Cutting Speeds**: 30-50 m/min for turning operations - **Feed Rates**: 0.1-0.3 mm/rev for optimal finish - **Coolant**: Recommended for all machining operations #### **7.2 Forming & Welding** - **Bend Radius**: Minimum 2× thickness for flat bar - **Weldability**: Good with TIG and MIG processes - **Filler Metal**: Matching composition recommended - **Preheat**: Generally not required for sections under 25 mm #### **7.3 Heat Treatment** - **Annealing Temperature**: 750-850°C, rapid cooling - **Stress Relieving**: 500-600°C, 1 hour per 25 mm thickness - **Atmosphere**: Protective atmosphere for scale-free results - **Grain Size**: Controlled to ASTM 5-8 for optimal properties --- ### **8. QUALITY ASSURANCE** #### **8.1 Material Certification** - **Chemical Analysis**: Certified spectrographic analysis - **Mechanical Testing**: Tensile and hardness certification - **Dimensional Verification**: 100% inspection to specifications - **Surface Quality**: Visual inspection per ASTM A484 #### **8.2 Testing Capabilities** - **Ultrasonic Testing**: For internal quality assessment - **Macroetch Examination**: For internal soundness verification - **Grain Size Analysis**: ASTM E112 compliance - **CTE Measurement**: Precision thermal expansion verification #### **8.3 Traceability** - **Heat Number Tracking**: Full material history maintained - **Mill Certificates**: EN 10204 3.1/3.2 certification - **Process Documentation**: Complete manufacturing records - **Custom Marking**: Customer-specific identification available --- ### **9. TECHNICAL ADVANTAGES** - **Excellent Thermal Stability**: Maintains dimensions across temperature ranges - **Superior Machinability**: Good chip formation and surface finish - **Perfect CTE Match**: Ideal for glass and ceramic applications - **High Strength**: Robust performance in structural applications - **Corrosion Resistance**: Suitable for industrial environments - **Consistent Quality**: Reliable performance in precision applications --- ### **10. PACKAGING & DELIVERY** - **Protective Packaging**: Individual wrapping or bundling - **Surface Protection**: Oiled or VCI paper for corrosion prevention - **Clear Identification**: Heat number and specification marking - **Standard Lengths**: Stock lengths or cut-to-size availability - **Special Requirements**: Custom packaging available --- **Note:** For critical machining applications requiring tight tolerances, stress relieving after rough machining is recommended. Consultation with our technical team is advised for applications requiring specific thermal expansion characteristics or specialized processing. Material samples and technical support available for application development.

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 2458 gallon liquid totes Special package is available on request.