Kovar,Alloy K Bar(Round bar, Flat bar),UNS K94610,E FORU

British Specs:，American Specs: ASTM F15 ASTM F26 AMS 7726 Wire AMS 7727 Bar and Forgings AMS 7728 Sheet, Strip and Plate MIL-I-23011 Class 1，German Specs:WS 1.3981,AFNOR NF A54-301

**Technical Data Sheet: Kovar / Alloy K Bar (Round Bar & Flat Bar) UNS K94610** **1.0 Product Overview** Kovar Bar (Alloy K Bar), standardized as UNS K94610, is a nickel-cobalt ferrous alloy supplied in both round bar and flat bar configurations. This controlled expansion alloy is specifically formulated to match the thermal expansion characteristics of hard glass and ceramic materials, making it essential for manufacturing precision components requiring reliable thermal compatibility in electronic, aerospace, and scientific applications. **2.0 Chemical Composition** | Element | Content (%) | Primary Function | |---------|-------------|------------------| | Fe | Balance | Base Element | | Ni | 28.5-29.5 | Thermal Expansion Control | | Co | 16.8-17.8 | Thermal Expansion Matching | | Mn | 0.20-0.50 | Deoxidizer | | Si | 0.10-0.30 | Deoxidizer | | Al | 0.05 max | Deoxidizer | | Mg | 0.05 max | Deoxidizer | | C | 0.02 max | Minimize carbide formation | | P | 0.02 max | - | | S | 0.02 max | - | *Note: The precise control of nickel and cobalt content ensures consistent thermal expansion properties matching borosilicate glass.* **3.0 Physical Properties** | Property | Metric Value | Imperial Value | Condition | |----------|--------------|----------------|-----------| | Density | 8.36 g/cm³ | 0.302 lb/in³ | Room Temperature | | Melting Point | 1450°C | 2640°F | - | | Thermal Conductivity | 17.3 W/m·K | 120 Btu·in/(hr·ft²·°F) | 20°C | | Mean CTE | 4.9-5.5 × 10⁻⁶/°C | 2.7-3.1 × 10⁻⁶/°F | 20-400°C | | Electrical Resistivity | 0.49 μΩ·m | 19.0 μΩ·in | 20°C | | Modulus of Elasticity | 138 GPa | 20.0 × 10⁶ psi | Room Temperature | | Curie Temperature | 435°C | 815°F | - | **4.0 Mechanical Properties** **4.1 Typical Properties (Annealed Condition)** - Tensile Strength: 517-586 MPa (75-85 ksi) - Yield Strength (0.2% Offset): 345-414 MPa (50-60 ksi) - Elongation: 25-35% - Hardness: 65-80 HRB - Reduction in Area: 45-60% **4.2 Cold Worked Properties** - Tensile Strength: 586-758 MPa (85-110 ksi) - Yield Strength: 483-620 MPa (70-90 ksi) - Elongation: 10-20% - Hardness: 80-100 HRB **5.0 Product Specifications** **5.1 Round Bar Specifications** - **Diameter Range:** 3.0 mm to 200 mm (0.125" to 8.0") - **Length:** 1000 mm to 3000 mm (39" to 118") - **Diameter Tolerance:** h9 for precision applications - **Straightness:** 0.5 mm per 300 mm maximum **5.2 Flat Bar Specifications** - **Thickness:** 3.0 mm to 50 mm (0.125" to 2.0") - **Width:** 10 mm to 200 mm (0.375" to 8.0") - **Length:** 1000 mm to 3000 mm (39" to 118") - **Flatness:** 0.1 mm per 100 mm maximum **6.0 Manufacturing Processes** **6.1 Production Methods** - Hot rolling from forged billets - Cold drawing for improved surface finish - Centerless grinding for tight tolerances - Annealing in hydrogen or vacuum atmosphere **6.2 Quality Control** - Ultrasonic testing per ASTM A388 - Dimensional verification - Surface quality inspection - Mechanical property testing **7.0 Heat Treatment** **7.1 Standard Annealing** - Temperature: 850-900°C (1560-1650°F) - Atmosphere: Hydrogen or vacuum recommended - Time: 30-60 minutes at temperature - Cooling: Rapid cool to 400°C, then air cool **7.2 Stress Relieving** - Temperature: 425-540°C (800-1000°F) - Time: 30-60 minutes - Atmosphere: Air or protective atmosphere **8.0 Product Applications** **8.1 Round Bar Applications** - Semiconductor lead frames - Electronic package pins and leads - Microwave component mounts - Vacuum feedthrough conductors - Optical mounting posts **8.2 Flat Bar Applications** - Power semiconductor bases - Circuit board mounting rails - Laser housing frames - Instrument chassis components - Heat sink mounting plates **8.3 Industry Specific Uses** - **Electronics:** IC package components, connector bases - **Aerospace:** Avionics mounts, satellite components - **Medical:** X-ray tube parts, medical laser components - **Telecommunications:** RF package bases, waveguide supports **9.0 International Standards & Specifications** | Standard Organization | Standard Number | Description | |----------------------|-----------------|-------------| | ASTM | F15 | Iron-Nickel-Cobalt Sealing Alloy | | AMS | 7724 | Rod and Bar Forms | | UNS | K94610 | Unified Numbering System | | DIN | 1.3981 | German Material Number | | JIS | H 4551 | Japanese Industrial Standard | | GB | GB/T 15018 | Chinese Standard | **10.0 Machining & Fabrication** **10.1 Machining Characteristics** - Good machinability in annealed condition - Use sharp, positive rake cutting tools - Recommended cutting speed: 30-45 m/min - Use soluble oil or chemical coolants - Moderate work hardening tendency **10.2 Forming & Welding** - Can be cold formed in annealed condition - Good weldability using GTAW and GMAW - Suitable for brazing with silver alloys - Stress relieve after welding or forming **11.0 Thermal Performance** **11.1 Expansion Characteristics** - Excellent match with borosilicate glass (Pyrex) - Compatible with 96% alumina ceramic - Low thermal expansion below Curie temperature - Predictable expansion behavior - Minimal thermal stress during sealing **11.2 Sealing Preparation** - Clean and degrease before use - Controlled oxidation for glass sealing - Surface activation for optimal bonding - Avoid contamination before sealing processes **12.0 Quality Assurance** **12.1 Testing & Certification** - Chemical composition analysis - Thermal expansion coefficient verification - Mechanical property testing - Ultrasonic testing for internal quality - Dimensional accuracy certification **12.2 Documentation** - Mill Test Certificates per EN 10204 3.1 - Full material traceability - Heat treatment records - Compliance with industry specifications Kovar Bar (Alloy K Bar, UNS K94610) in both round and flat configurations provides manufacturers with versatile raw materials for producing precision components requiring exact thermal expansion matching with glass and ceramics. The availability in different bar forms enables efficient manufacturing of components for electronic packaging, aerospace systems, and scientific instruments where reliable thermal performance and dimensional stability are critical requirements.

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 2354 gallon liquid totes Special package is available on request.