C17200 beryllium copper stands as a premier copper alloy renowned for its exceptional combination of high strength, excellent electrical and thermal conductivity, and remarkable corrosion resistance. This age-hardenable alloy, often specified in demanding applications across aerospace, automotive, and electronics industries, achieves its peak performance through a precise heat treatment process. At Dongguan Stirling Metal Products Co., Ltd., we leverage our deep expertise in CNC machining to deliver C17200 components that meet the most stringent engineering requirements. The alloy’s unique ability to attain tensile strengths exceeding 1,400 MPa while maintaining electrical conductivity up to 28% IACS makes it indispensable for high-reliability applications where failure is not an option.
1. C17200 Basic Information
C17200, also known as beryllium copper or CuBe2, is a precipitation-hardening copper alloy containing approximately 2% beryllium. Its unique ability to be hardened through heat treatment yields tensile strengths exceeding 1,400 MPa in the fully aged condition, rivaling many high-strength steels while maintaining superior electrical conductivity. The alloy is available in various tempers, including solution-annealed (A), cold-worked (1/4H, 1/2H, H), and precipitation-hardened (HT, AT) conditions, each offering distinct mechanical and physical properties tailored to specific applications. The precipitation-hardening process involves solution annealing at 780-800°C followed by rapid quenching, then aging at 315-345°C for 2-3 hours to achieve peak hardness. This metallurgical transformation creates coherent beryllide precipitates that impede dislocation motion, resulting in the alloy’s exceptional strength.
2. Chemical Composition
The precise chemical composition of C17200 is critical to achieving its desired properties. The beryllium content, in particular, governs the alloy’s response to aging and its final strength. The following table details the standard composition ranges as specified by ASTM B196/B196M:
| Element | Content (%) | Role |
|---|---|---|
| Copper (Cu) | Balance (approx. 97.5-98.5%) | Base metal, provides conductivity and corrosion resistance |
| Beryllium (Be) | 1.80 – 2.00 | Primary hardening element, enables precipitation strengthening |
| Cobalt (Co) + Nickel (Ni) | 0.20 – 0.60 | Grain refiner, improves age-hardening response and ductility |
| Iron (Fe) | ≤ 0.15 | Impurity, controlled to minimize embrittlement |
| Aluminum (Al) | ≤ 0.15 | Impurity, controlled for consistent properties |
| Silicon (Si) | ≤ 0.15 | Impurity, controlled for machinability |
| Lead (Pb) | ≤ 0.005 | Impurity, minimized for environmental compliance |
Note: The balance is copper with trace elements. Strict control of beryllium and cobalt/nickel is essential for achieving optimal mechanical and electrical properties after heat treatment. The cobalt and nickel additions act as grain refiners, limiting grain growth during solution annealing and promoting uniform precipitation during aging. Even minor deviations in beryllium content can shift the aging response by 10-15°C, necessitating precise compositional control within ±0.05% Be for consistent heat treatment results.
3. Mechanical & Physical Properties
C17200 exhibits a unique combination of properties that make it indispensable in high-reliability applications. The following tables present typical values for the alloy in the precipitation-hardened (HT) condition, which is the most common for structural components.
Mechanical Properties (HT Condition)
| Property | Value | Unit | Standard |
|---|---|---|---|
| Tensile Strength (Ultimate) | 1,200 – 1,400 | MPa | ASTM E8/E8M |
| Yield Strength (0.2% Offset) | 1,000 – 1,200 | MPa | ASTM E8/E8M |
| Elongation in 50 mm | 2 – 5 | % | ASTM E8/E8M |
| Hardness (Rockwell C) | 38 – 44 | HRC | ASTM E18 |
| Hardness (Vickers) | 360 – 420 | HV | ASTM E384 |
| Modulus of Elasticity | 128 – 131 | GPa | ASTM E111 |
| Fatigue Strength (10^7 cycles, rotating beam) | 350 – 450 | MPa | ASTM E466 |
Physical Properties (HT Condition)
| Property | Value | Unit | Notes |
|---|---|---|---|
| Density | 8.25 – 8.35 | g/cm³ | At 20°C |
| Thermal Conductivity | 105 – 130 | W/m·K | At 20°C, depends on temper |
| Electrical Conductivity | 22 – 28 | %IACS | At 20°C, depends on temper |
| Specific Heat Capacity | 420 | J/kg·K | At 20°C |
| Thermal Expansion Coefficient | 16.7 × 10⁻⁶ | /°C | 20-300°C |
| Melting Range | 860 – 980 | °C | Solidus to liquidus |
| Electrical Resistivity | 6.2 – 7.8 × 10⁻⁸ | Ω·m | At 20°C |
These properties highlight the alloy’s exceptional strength-to-weight ratio and its ability to dissipate heat efficiently, making it ideal for high-current electrical connectors and spring contacts. The modulus of elasticity of 128-131 GPa is approximately 60% higher than that of pure copper, providing excellent stiffness for precision components. The fatigue strength of 350-450 MPa at 10^7 cycles ensures long-term reliability in cyclic loading applications such as relay springs and electrical contacts.
4. Corrosion Resistance
C17200 offers excellent corrosion resistance in a wide range of environments, though its performance is influenced by the specific conditions. The alloy forms a protective oxide layer that provides durability in many industrial and marine settings. Below is a detailed breakdown of its corrosion behavior:
- Atmospheric Environment: Excellent resistance to urban, industrial, and marine atmospheres. The alloy exhibits minimal tarnishing and retains its mechanical integrity over decades of exposure. Corrosion rates are typically less than 0.0025 mm/year in rural atmospheres and 0.005 mm/year in industrial environments.
- Fresh Water: Highly resistant to fresh water, including soft and hard water, with negligible corrosion rates (<0.01 mm/year). Suitable for plumbing and water-handling components. In deionized water, corrosion rates remain below 0.005 mm/year.
- Seawater: Good resistance to seawater corrosion, particularly in low-velocity conditions. However, in high-velocity or turbulent seawater, erosion-corrosion may occur. Protective coatings or cathodic protection are recommended for long-term immersion. Typical corrosion rates in static seawater are 0.01-0.02 mm/year.
- Acids and Alkalis: General corrosion resistance in dilute acids (e.g., sulfuric, hydrochloric) and alkalis (e.g., sodium hydroxide) at room temperature. Avoid concentrated oxidizing acids (e.g., nitric acid) which can cause rapid attack. In 10% sulfuric acid at 25°C, corrosion rates are approximately 0.1 mm/year.
- Stress Corrosion Cracking: C17200 is susceptible to stress corrosion cracking in ammonia-containing environments and certain chloride solutions. Proper heat treatment (stress relief) and design considerations mitigate this risk. The threshold stress for SCC in ammonia environments is approximately 200 MPa for the HT condition.
5. Typical Applications
The unique properties of C17200 make it the material of choice for critical components where reliability and performance are paramount. Key applications include:
- Electrical Industry: High-performance connectors, relay contacts, switch components, and current-carrying springs requiring high conductivity and fatigue resistance. Typical current ratings for C17200 contacts range from 10-100 A depending on geometry.
- Aerospace & Defense: Landing gear bushings, bearings, valve guides, and instrument components subjected to high loads and wear. The alloy’s non-sparking property makes it ideal for fuel system components.
- Oil & Gas: Non-sparking tools, valve seats, and downhole components where safety and corrosion resistance are critical. C17200 is used in sour gas environments (NACE MR0175 compliant) with proper heat treatment.
- Automotive: Fuel injector components, sensor housings, and electrical terminals in demanding under-hood environments. Operating temperature range: -50°C to +200°C.
- Medical Devices: Surgical instruments, dental tools, and implantable devices requiring biocompatibility and high strength. The alloy meets ISO 10993 biocompatibility standards.
- CNC Machined Parts: Precision components such as gears, cams, and molds where tight tolerances (±0.01 mm) and excellent surface finish are required. Typical applications include mold inserts for plastic injection molding.
6. CNC Machining Performance
CNC machining of C17200 requires careful consideration of its high strength and work-hardening characteristics. The alloy is classified as having moderate to good machinability, but optimal results depend on proper tooling and parameters. Below are detailed recommendations based on our extensive experience at Dongguan Stirling Metal Products Co., Ltd.
Recommended CNC Machining Parameters
| Operation | Cutting Speed (m/min) | Feed Rate (mm/rev) | Depth of Cut (mm) | Tool Material | Coolant |
|---|---|---|---|---|---|
| Turning (Roughing) | 60 – 100 | 0.15 – 0.30 | 2.0 – 4.0 | Carbide (K10-K20) | Water-soluble emulsion |
| Turning (Finishing) | 100 – 150 | 0.05 – 0.15 | 0.5 – 1.0 | Carbide (K10-K20) or CBN | Water-soluble emulsion |
| Milling (Roughing) | 50 – 80 | 0.10 – 0.25 (mm/tooth) | 1.0 – 3.0 | Carbide (K20-K30) | Flood coolant |
| Milling (Finishing) | 80 – 120 | 0.05 – 0.10 (mm/tooth) | 0.3 – 0.8 | Carbide (K20-K30) or PCD | Flood coolant |
| Drilling | 30 – 60 | 0.05 – 0.15 | N/A | HSS-Co or Carbide | High-pressure coolant |
| Threading | 20 – 40 | 0.10 – 0.20 (per pass) | N/A | Carbide thread mill | Oil-based coolant |
Key Machining Considerations
- Tool Wear: C17200’s high strength accelerates tool wear. Use sharp, coated carbide tools (e.g., TiAlN or AlTiN coatings) to extend tool life. For high-volume production, consider CBN or PCD tools. Typical tool life for carbide inserts is 15-30 minutes at recommended speeds.
- Heat Generation: The alloy’s low thermal conductivity (compared to pure copper) can lead to heat buildup at the cutting edge. Use generous coolant flow (flood or high-pressure) to dissipate heat and prevent work hardening. Coolant pressure of 20-40 bar is recommended for drilling operations.
- Work Hardening: C17200 work-hardens rapidly, particularly during interrupted cuts. Maintain consistent feed rates and avoid dwells to minimize surface hardening. Use light finishing passes to achieve the desired surface finish. The work-hardened layer can reach depths of 0.1-0.3 mm if improper parameters are used.
- Chip Control: Chips can be stringy and difficult to manage. Use chip breakers or peck drilling cycles to produce manageable chips. Ensure proper chip evacuation to prevent re-cutting. Chip thickness should be maintained between 0.05-0.15 mm for optimal control.
- Surface Finish: With optimized parameters, surface finishes of Ra 0.4 µm or better are achievable. For mirror-like finishes, use PCD tools with fine feeds (0.02-0.05 mm/rev) and high speeds (150-200 m/min). Typical surface roughness values for finishing operations are Ra 0.2-0.4 µm.
- Safety: Beryllium dust and fumes are toxic. Always use proper ventilation, mist collectors, and personal protective equipment (PPE) when machining. Wet machining is strongly recommended to suppress dust. Airborne beryllium levels must be maintained below 0.2 µg/m³ as per OSHA standards.
7. Procurement Guide
When sourcing C17200, it is essential to verify material certification and heat treatment condition. The following price ranges are indicative for standard forms and sizes, subject to market fluctuations and quantity discounts:
| Product Form | Size Range | Price (USD/kg) | Typical Temper |
|---|---|---|---|
| Sheet/Plate | 0.5 – 50 mm thick | $45 – $65 | A, 1/4H, HT |
| Bar/Rod | 6 – 100 mm diameter | $50 – $70 | A, 1/2H, HT |
| Tube | 10 – 80 mm OD | $55 – $75 | A, HT |
| Wire | 0.5 – 5 mm diameter | $60 – $80 | A, 1/4H |
| Custom Forgings | As per drawing | $70 – $100 | As specified |
All materials supplied by Dongguan Stirling Metal Products Co., Ltd. are accompanied by mill test certificates (MTC) and are traceable to ASTM B196/B196M or equivalent standards. We maintain an inventory of over 50 tons of C17200 in various forms and tempers, ensuring rapid delivery for urgent requirements. Our quality assurance team performs 100% hardness testing and conductivity measurement on all incoming material to verify compliance with specifications.
8. Our Services
Dongguan Stirling Metal Products Co., Ltd. specializes in providing C17200 material + CNC machining one-stop service, ensuring that your components meet the highest standards of quality and precision. Our integrated approach reduces lead times and eliminates supply chain complexities.
- ✅ Material Procurement: Genuine product guarantee, complete material certificates (MTC, EN 10204 3.1), and stock availability for standard sizes. We source from leading mills such as Materion and NGK. Our inventory includes over 100 standard sizes of bar, sheet, and tube.
- ✅ CNC Machining: Precision ±0.01 mm, smooth surface finish down to Ra 0.2 µm. Our 5-axis CNC centers and Swiss-type lathes handle complex geometries with ease. We operate 20 CNC machines with spindle speeds up to 20,000 RPM.
- ✅ Heat Treatment: In-house solution annealing and precipitation hardening capabilities, with precise temperature control (±5°C) and full documentation. Our furnaces can handle parts up to 600 mm in length and 300 kg in weight.
- ✅ Sample Production: Fast delivery in 3-5 days for prototypes and first-article inspections. We provide PPAP documentation upon request. Our rapid prototyping service includes 3D CAD modeling and DFM analysis.
- ✅ Batch Production: Delivery in 7-15 days for production runs, with rigorous quality control (CMM, hardness testing, conductivity measurement). Our quality system is ISO 9001:2015 certified.
- ✅ Surface Treatment: Polishing, electroplating (gold, silver, nickel), passivation, and anti-tarnish coatings to meet specific environmental requirements. We offer MIL-SPEC compliant coatings for defense applications.
Free Quote consultation, welcome to Contact Us! Our engineering team is ready to assist with material selection, design for manufacturability (DFM), and cost optimization. Let us help you unlock the full potential of C17200 beryllium copper for your next project. Contact us today at +86-769-XXXX-XXXX or email sales@stirlingmetal.com for a prompt response within 24 hours.
