UNS C17500 Cobalt Beryllium Copper Seamless Tube
UNS C17500 Cobalt Beryllium Copper Seamless Tube Full Analysis: Special Precision Copper Tube with High Temperature Resistance & High Electrical Conductivity
UNS C17500, commonly known as UNS C17500 copper pipe cobalt beryllium copper seamless tube, is a low-beryllium high-cobalt precipitation-hardened copper alloy seamless tube governed by ASTM B937 Standard Specification for Copper-Beryllium Seamless Tubes. Distinct from high-beryllium C17200 copper tubes, it features a triple core performance of high mechanical strength, superior electrical & thermal conductivity, and excellent high-temperature stability.
Manufactured via hot extrusion followed by precision cold rolling, this seamless tube is weld-free with high inner and outer surface finish, tight dimensional tolerances, suitable for heat transfer fluid pipelines, conductive bus channels, and precision machined components.
1. Basic Material Definition & Applicable Standards
1.1 Standard Chemical Composition (Mass Fraction, %)
| Element | Standard Range | Metallurgical Function |
|---|---|---|
| Cu | Remainder | Matrix for electrical & thermal conduction |
| Be (Beryllium) | 0.40~0.70 | Forms Co₂Be precipitates to boost hardness and elasticity |
| Co (Cobalt) | 2.40~2.70 | Refines grain structure and drastically improves high-temperature dimensional stability |
| Fe / Al / Si | ≤0.10 / ≤0.20 / ≤0.20 | Strict impurity control to prevent conductivity loss |
Compared with C17200 (1.8~2.0% Be), the low-beryllium formulation lowers health hazards from machining dust and optimizes raw material cost, making it the preferred tube substrate for mass-produced industrial high-temperature conductive parts.
2. Core Physical & Mechanical Properties (Precipitation Hardened Temper)
2.1 Fundamental Physical Parameters
Density: 8.83 g/cm³
Electrical Conductivity: 45~60% IACS, far superior to C17200 (20~30% IACS) with lower heat generation under energization
Thermal Conductivity: 195~200 W/(m·K), 3~4 times that of tool steel for outstanding heat dissipation
Linear Thermal Expansion Coefficient: 18×10⁻⁶ /°C (20~200°C)
Magnetic Property: Completely non-magnetic
Safety Feature: Non-sparking upon impact, compatible with oil & gas, chemical explosion-proof working conditions
2.2 Mechanical Properties After Precipitation Hardening
Tensile Strength: 680~980 MPa
0.2% Offset Yield Strength: ≥550 MPa
Modulus of Elasticity: 138 GPa, exceptional resistance to stress relaxation with minimal clamping force degradation under long-term 150°C high-temperature service
Elongation: ≥10%; soft temper enables bending and deep drawing for complex tube forming
3. Core Application Fields of UNS C17500 Seamless Tube
Leveraging three core merits: high conductivity, heat resistance, and high-strength seamless hollow structure, it covers all high-end manufacturing sectors:
3.1 Resistance Welding Equipment (Largest Application Scenario)
Spot welding electrode sleeves, seam welding conductive clamps, water-cooled tubes for projection welding dies. The hollow seamless passage circulates cooling water to rapidly dissipate welding heat. UNS C17500 resists softening at elevated temperatures, resisting wear and deformation during long-term spot welding of stainless steel and high-strength steel, delivering a service life 3 times longer than pure copper.
3.2 New Energy & Power Electrical Industry
- High-voltage terminal sleeves for new energy vehicle BMS, conductive spring tubes for high-power relays
- Hollow conductors for 5G millimeter-wave RF connectors, sleeves for high-speed test probes
- High-current fuse clamps, conductive pipelines for circuit breakers, signal transmission tubes for high-temperature electric control systems
The hollow design accommodates cable routing and water cooling, while low conductive loss guarantees integrity of high-frequency signals.
3.3 Thermal Management for Molds
Water-cooled seamless tubes for injection molding and die-casting molds. Ultra-high thermal conductivity rapidly extracts heat from mold cavities to shorten plastic molding cycles and reduce product warpage. The seamless tube wall provides stable pressure resistance with zero leakage risk, ideal for precision medical and electronic plastic molds.
3.4 Semiconductors & Precision Testing Equipment
Sleeves for semiconductor probe cards, elastic heat-conductive tubes for chip test sockets. Non-magnetic with minimal signal attenuation, it withstands millions of insertion-extraction fatigue cycles, suitable for dust-free precision laboratory environments.
3.5 Aerospace, Explosion-Proof & Marine Equipment
- High-frequency conductive pipelines for radar and guidance systems, high-temperature signal tubes for spacecraft
- Non-magnetic elastic explosion-proof pipelines for underground oil & gas wells, hollow components for chemical explosion-proof switches (non-sparking upon impact)
- Water-cooled conductive sleeves for marine vessels, shaft sleeves for seawater pumps, stable long-term operation with excellent seawater corrosion resistance
4. Selection, Machining & Service Guidelines for UNS C17500 Seamless Tube
4.1 Grade Comparison: UNS C17500 vs UNS C17200 Seamless Tube
| Grade | Beryllium Content | Electrical Conductivity | Core Advantages | Applicable Tube Scenarios |
|---|---|---|---|---|
| C17500 | 0.4~0.7% | 45~60% IACS | Excellent heat resistance, high thermal conductivity, cost-effective | Water-cooled welding electrodes, mold cooling lines, high-current conductive tubes |
| C17200 | 1.8~2.0% | 20~30% IACS | Extreme elasticity, ultra-high hardness | Micro precision spring tubes, elastic components with low conductivity requirements |
4.2 Machining & Heat Treatment Precautions
Cutting & Turning
Precipitation-hardened tubes feature high hardness; carbide cutting tools are recommended with reduced feed rates for superior surface finish.
Welding Rules
Prioritize tin brazing, silver brazing and resistance spot welding. Open-flame fusion welding is prohibited, as extreme heat will break down precipitation strengthening phases and degrade tube mechanical strength.
Temperature Limit
Maximum Continuous Operating Temperature: ≤250°C; sustained exposure above 350°C causes material softening and conductivity decline.
Safety Protection
Dust extraction equipment is mandatory during cutting and grinding to prevent inhalation of beryllium metal dust. Finished tubes shall be stored in dry ambient conditions to avoid rust.
5. Conclusion
UNS C17500 cobalt beryllium copper seamless tube is a special seamless copper alloy balancing mechanical strength, electrical/thermal conductivity and high-temperature stability. Built on low-beryllium high-cobalt precipitation-hardened metallurgy and weld-free precision forming technology, it addresses core industry drawbacks of pure copper (insufficient strength), high-beryllium copper (poor conductivity) and conventional alloys (limited heat resistance).