C12000 phosphorus deoxidized copper stands as a benchmark material in the copper alloy family, engineered specifically to overcome the limitations of oxygen-bearing coppers in welding and high-temperature applications. By introducing a controlled phosphorus residual during the refining process, this alloy eliminates oxygen content to below 0.001%, effectively preventing hydrogen embrittlement and steam cracking that plague electrolytic tough pitch copper (C11000) during fusion welding. The result is a material that combines the inherent conductivity of copper with exceptional weldability, formability, and corrosion resistance, making it indispensable for critical components in electrical power distribution, marine engineering, and precision CNC-machined assemblies. At Dongguan Stirling Metal Products Co., Ltd., we leverage decades of metallurgical expertise to supply and machine C12000 to the most demanding specifications, ensuring that every part delivers reliable performance in service.
1. C12000 Basic Information
C12000, also designated as UNS C12000 or DHP (Deoxidized High Phosphorus) copper, is a wrought copper alloy defined under ASTM B152 (sheet and strip), ASTM B187 (bar), and ASTM B188 (tube). It contains a minimum of 99.90% copper with a controlled phosphorus residual of 0.015% to 0.040%, which serves as a deoxidizer to reduce oxygen content to below 0.001%. This deoxidation process eliminates the risk of steam embrittlement during welding, brazing, or soldering, as no oxygen is available to react with hydrogen at elevated temperatures. The material exhibits excellent electrical conductivity (85-90% IACS), high thermal conductivity (340-360 W/m·K), and outstanding corrosion resistance in both fresh and saltwater environments. Its weldability is rated as excellent, making it suitable for gas tungsten arc welding (GTAW), gas metal arc welding (GMAW), and brazing without the need for flux in many applications. C12000 is available in various tempers, including annealed (O60), half-hard (H02), and hard (H04), allowing designers to tailor mechanical properties to specific forming and service requirements.
2. Chemical Composition
The chemical composition of C12000 is tightly controlled to ensure consistent deoxidation and mechanical properties. The phosphorus content is critical: too low and oxygen removal is incomplete; too high and electrical conductivity decreases. The following table provides the standard composition ranges per ASTM B152:
| Element | Composition Range (%) | Typical Value (%) | ASTM B152 Limit |
|---|---|---|---|
| Copper (Cu) | 99.90 min | 99.95 | 99.90 min |
| Phosphorus (P) | 0.015 – 0.040 | 0.025 | 0.015 – 0.040 |
| Oxygen (O) | 0.001 max | <0.001 | 0.001 max |
| Iron (Fe) | 0.005 max | 0.002 | 0.005 max |
| Lead (Pb) | 0.005 max | 0.001 | 0.005 max |
| Zinc (Zn) | 0.005 max | 0.001 | 0.005 max |
| Tin (Sn) | 0.005 max | 0.001 | 0.005 max |
| Nickel (Ni) | 0.005 max | 0.001 | 0.005 max |
| Other Impurities (Total) | 0.03 max | <0.01 | 0.03 max |
Note: The low impurity levels ensure high electrical conductivity and consistent welding behavior. The phosphorus residual is precisely controlled to balance deoxidation efficiency with conductivity requirements. For critical applications, Dongguan Stirling Metal Products Co., Ltd. can supply material with certified composition per customer specifications, including tighter phosphorus ranges (e.g., 0.020-0.030%) for enhanced weldability.
3. Mechanical & Physical Properties
C12000 exhibits a favorable combination of strength, ductility, and thermal performance. The mechanical properties vary with temper condition (annealed, half-hard, or hard). Typical values for the annealed condition (O60) are shown below:
| Property | Value (Annealed O60) | Value (Half-Hard H02) | Value (Hard H04) | Unit |
|---|---|---|---|---|
| Tensile Strength | 220 – 260 | 290 – 350 | 360 – 420 | MPa |
| Yield Strength (0.2% offset) | 70 – 100 | 200 – 280 | 300 – 370 | MPa |
| Elongation (in 50 mm) | 45 – 55 | 15 – 25 | 5 – 10 | % |
| Hardness (Rockwell F) | 45 – 55 | 70 – 85 | 90 – 100 | HRF |
| Hardness (Brinell 500 kg) | 40 – 50 | 65 – 80 | 85 – 100 | HB |
| Hardness (Vickers) | 45 – 55 | 75 – 90 | 95 – 110 | HV |
| Density | 8.94 | 8.94 | 8.94 | g/cm³ |
| Thermal Conductivity (at 20°C) | 350 | 340 | 330 | W/m·K |
| Electrical Conductivity (at 20°C) | 90 | 85 | 80 | %IACS |
| Electrical Resistivity (at 20°C) | 0.0191 | 0.0203 | 0.0216 | µΩ·m |
| Modulus of Elasticity | 115 | 115 | 115 | GPa |
| Poisson’s Ratio | 0.34 | 0.34 | 0.34 | – |
| Melting Point (Liquidus) | 1083 | 1083 | 1083 | °C |
| Melting Point (Solidus) | 1065 | 1065 | 1065 | °C |
| Specific Heat Capacity (at 20°C) | 385 | 385 | 385 | J/kg·K |
| Thermal Expansion Coefficient (20-100°C) | 17.0 | 17.0 | 17.0 | µm/m·°C |
These properties make C12000 ideal for applications requiring high thermal dissipation, such as welding electrodes, heat exchanger tubes, and electrical busbars. The annealed condition offers maximum ductility for forming operations, while the half-hard temper provides improved strength for structural components. The hard temper is used where wear resistance and rigidity are needed, though at the expense of ductility. Note that thermal conductivity decreases slightly with increasing hardness due to lattice distortions, but remains above 330 W/m·K even in the hard condition.
4. CNC Machining Characteristics
CNC machining of C12000 requires careful parameter selection due to its high ductility and thermal conductivity. The material tends to form long, stringy chips that can cause chip entanglement and poor surface finish if not managed properly. Recommended machining parameters for common operations are provided below:
| Operation | Cutting Speed (m/min) | Feed Rate (mm/rev) | Depth of Cut (mm) | Tool Material | Coolant | Expected Surface Finish (Ra, µm) |
|---|---|---|---|---|---|---|
| Turning (Roughing) | 150 – 250 | 0.15 – 0.30 | 2.0 – 4.0 | Carbide (K10/K20) | Water-soluble oil (5-8% concentration) | 1.6 – 3.2 |
| Turning (Finishing) | 200 – 300 | 0.05 – 0.12 | 0.25 – 0.75 | Carbide (K10) or PCD | Water-soluble oil (5-8% concentration) | 0.2 – 0.8 |
| Milling (Roughing) | 120 – 200 | 0.10 – 0.20 mm/tooth | 2.0 – 3.0 | Carbide (K20) | Flood coolant (water-soluble oil) | 3.2 – 6.3 |
| Milling (Finishing) | 180 – 250 | 0.05 – 0.10 mm/tooth | 0.25 – 0.50 | Carbide (K10) or PCD | Flood coolant (water-soluble oil) | 0.4 – 1.6 |
| Drilling (HSS) | 30 – 60 | 0.08 – 0.15 | N/A | HSS-Co (M42) or Carbide (K20) | Water-soluble oil (5-8% concentration) | 3.2 – 6.3 |
| Drilling (Carbide) | 80 – 120 | 0.10 – 0.20 | N/A | Carbide (K20) | Water-soluble oil (5-8% concentration) | 1.6 – 3.2 |
| Threading (Tapping) | 5 – 10 | N/A | N/A | HSS-E (M35) or Carbide (K10) | Oil-based lubricant (e.g., sulfurized oil) | N/A |
| Reaming | 80 – 120 | 0.05 – 0.10 | 0.10 – 0.25 | Carbide (K10) or HSS-Co | Water-soluble oil (5-8% concentration) | 0.4 – 1.6 |
Key machining considerations for C12000 include:
- Chip Control: Use chip breakers or peck drilling cycles to prevent long, continuous chips. High-pressure coolant (40-70 bar) is recommended for deep hole drilling. For turning, use positive rake angles (10-15°) to promote chip breaking.
- Tool Wear: Due to the material’s softness, built-up edge (BUE) can occur at low cutting speeds. Maintain cutting speeds above 150 m/min to minimize BUE and achieve a mirror-like finish. For finishing operations, PCD tools can achieve surface roughness down to Ra 0.1 µm.
- Surface Finish: With proper parameters, surface roughness down to Ra 0.2 µm can be achieved. Use PCD tools for ultra-fine finishes on decorative components. For threaded parts, use roll tapping to improve surface finish and thread strength.
- Thermal Management: C12000’s high thermal conductivity rapidly dissipates heat from the cutting zone. Use flood coolant to prevent thermal expansion and maintain dimensional accuracy within ±0.01 mm. For high-precision parts, consider using a coolant temperature controller (±1°C).
- Work Hardening: The material work-hardens minimally, but excessive rubbing can cause surface hardening. Use sharp tools and consistent feed rates to avoid this. For interrupted cuts (e.g., milling), use climb milling to reduce work hardening.
- Tool Geometry: Use tools with sharp cutting edges (edge radius <0.01 mm) and polished rake faces to reduce friction. For drilling, use split-point drills to reduce thrust forces and improve hole quality.
5. Corrosion Resistance
C12000 phosphorus deoxidized copper exhibits outstanding corrosion resistance in a wide range of environments, making it suitable for marine, industrial, and architectural applications. The deoxidized structure eliminates oxygen-related corrosion mechanisms such as pitting in high-temperature water. Performance in specific environments is detailed below:
- Atmospheric Environment: Excellent resistance to urban, industrial, and marine atmospheres. Forms a protective patina (greenish-brown) over time that prevents further corrosion. Corrosion rate: <0.5 µm/year in rural atmospheres, <2.5 µm/year in industrial atmospheres, <1.5 µm/year in marine atmospheres. Patina formation takes 5-10 years in urban environments.
- Fresh Water: Highly resistant to fresh water, including soft and hard water. Corrosion rate: <1 µm/year at flow rates up to 2 m/s. Suitable for potable water systems (meets NSF/ANSI 61 standards). In stagnant water, corrosion rate increases to <5 µm/year due to differential aeration cells.
- Seawater: Good resistance to stagnant and flowing seawater. Corrosion rate: 5-15 µm/year in quiescent seawater, <5 µm/year in flowing seawater (1-2 m/s). Resistant to biofouling due to copper ion release (0.5-1.0 µg/cm²/day). Not recommended for high-velocity seawater (>3 m/s) where erosion-corrosion may occur.
- Acids and Alkalis: General resistance to non-oxidizing acids (e.g., hydrochloric, sulfuric) at low concentrations (<10%) and room temperature. Not recommended for oxidizing acids (e.g., nitric) or strong alkalis (pH>11). In dilute sulfuric acid (5%), corrosion rate is <50 µm/year at 20°C.
- Soil: Excellent resistance to most soil types, including clay, sand, and loam. Corrosion rate: <2 µm/year in neutral soils. In acidic soils (pH<5), corrosion rate increases to 10-20 µm/year. Use protective coatings for buried applications.
- High-Temperature Water: Superior resistance to deaerated water up to 250°C, making it ideal for heat exchangers and boiler feedwater systems. In oxygenated water at 100°C, corrosion rate is <10 µm/year. Avoid use in steam condensate systems with high oxygen content.
- Chemical Environments: Resistant to most organic chemicals, including alcohols, ketones, and hydrocarbons. Not recommended for ammonia or ammonium compounds, which cause stress corrosion cracking in copper alloys.
6. Typical Applications
C12000’s combination of weldability, conductivity, and corrosion resistance enables its use in diverse industries. Key applications include:
- Electrical Industry: Busbars (up to 2000 A rating), switchgear components, welding electrodes (for resistance welding), electrical connectors requiring high conductivity and reliable joints. Used in power distribution systems up to 600 V.
- Shipbuilding: Propeller shafts (up to 500 mm diameter), valve bodies (for seawater systems), heat exchanger tubes (up to 25 mm OD), and seawater piping systems where corrosion resistance and weldability are critical. Meets ASTM B171 for marine applications.
- Plumbing and HVAC: Water pipes (Type L and M), fittings (solder-type and compression), and refrigeration tubing (ASTM B280) that must withstand brazing and soldering without embrittlement. Rated for pressures up to 20 bar at 65°C.
- Automotive: Radiator cores (with 0.1 mm fins), oil coolers, and brake line fittings requiring leak-tight welds and thermal efficiency. Used in electric vehicle battery cooling systems due to high thermal conductivity.
- CNC Machining Parts: Precision components such as valve seats (for hydraulic systems), pump impellers (for chemical pumps), and decorative hardware where tight tolerances (±0.01 mm) and smooth finishes (Ra 0.4 µm) are required. Typical part sizes range from 10 mm to 500 mm.
- Architecture: Roofing (standing seam systems), flashing, and ornamental features that benefit from the material’s natural patina and long-term durability. Used in historic restoration projects for authentic appearance.
- Medical Devices: Non-sparking tools and equipment used in oxygen-rich environments due to the absence of oxygen in the material. Used in MRI shielding components due to non-magnetic properties.
- Heat Exchangers: Shell-and-tube heat exchangers for chemical processing, with tube diameters from 6 mm to 50 mm. Operating temperatures up to 250°C and pressures up to 30 bar.
7. Why Choose Dongguan Stirling Metal Products Co., Ltd.
Dongguan Stirling Metal Products Co., Ltd. is a trusted partner for C12000 material supply and CNC machining services. Our expertise in processing phosphorus deoxidized copper ensures that every component meets the highest standards of quality and performance. We offer:
- Material Certification: All C12000 stock is supplied with full mill test certificates (MTC) per ASTM B152, ensuring traceability and compliance with international standards. We maintain inventory of over 50 tons in various forms (sheet, bar, tube, plate) with sizes from 0.5 mm to 200 mm thickness.
- Precision CNC Machining: Our 5-axis CNC machines (DMG MORI, Mazak) achieve tolerances as tight as ±0.005 mm on critical dimensions, with surface finishes down to Ra 0.2 µm using PCD tooling. We offer CMM inspection with accuracy of ±0.001 mm.
- Welding Expertise: In-house GTAW and GMAW capabilities for fabricating complex assemblies, with 100% leak testing on pressure-containing parts (helium mass spectrometry to 1×10⁻⁹ mbar·L/s). We hold ASME Section IX welding qualifications.
- Rapid Prototyping: Sample parts delivered in 3-5 days using our dedicated prototyping cell, with full dimensional inspection reports. We offer design for manufacturability (DFM) feedback to optimize your designs for C12000.
- Batch Production: Efficient production runs with delivery in 7-15 days for quantities up to 10,000 pieces, supported by statistical process control (SPC) with CpK values >1.33. We use automated pallet systems for 24/7 production capability.
- Surface Treatment: Comprehensive finishing options including electropolishing (to Ra 0.1 µm), passivation (per ASTM A967), and plating (silver, nickel, tin) to enhance corrosion resistance and aesthetics. We offer RoHS-compliant finishes.
- Technical Support: Our engineering team provides material selection guidance, welding procedure specifications (WPS), and machining parameter optimization for your specific application. We offer free sample machining for first-time customers.
Contact Dongguan Stirling Metal Products Co., Ltd. today for a free quotation and technical consultation. Let our expertise in C12000 phosphorus deoxidized copper help you achieve superior product performance and manufacturing efficiency. We serve customers in over 30 countries across North America, Europe, and Asia, with a 98% on-time delivery rate and ISO 9001:2015 certification.
