I. Chemical composition and naming rules
C70600 belongs to copper-nickel alloy (white copper) series, its composition is:
Copper (Cu): 65%-70
Nickel (Ni): 9%-11%
Iron (Fe): 1.0%-1.8% (to enhance corrosion resistance)
Manganese (Mn): ≤ 1.0% (to improve processing performance)
Others: zinc (Zn), tin (Sn), lead (Pb) and other impurities total ≤ 1.0%.
The alloy is also known as "90-10 copper-nickel alloy" or BFe10-1-1 white copper, in accordance with ASTM B576 standard.
Physical Properties
Density: 8.94 g/cm³, close to pure copper but with better mechanical properties.
Melting point: 1149-1171, suitable for high temperature environment.
Thermal conductivity: 50.2 W/(m-K) (at 20), can meet the demand for heat dissipation.
Coefficient of Thermal Expansion: 16.5×10-⁶/C (20-100), better than C71500 and other similar alloys.
Electrical conductivity: 7.50 MS/m (about 10% IACS), suitable for low current electrical components.
III. Mechanical Properties
Tensile strength:
Annealed state: 275-380 MPa
Cold working state: up to 650 MPa
Yield strength: 140-250 MPa (annealed state), elevated to 600 MPa after cold working.
Elongation: annealed state ≥ 28% (when strip thickness ≥ 0.3 mm)
Hardness:
Brinell hardness (HB): 110-1405
Rockwell hardness (HRB): 50-705
Creep resistance: 500 under the creep rate ≤ 1 × 10-⁷ / s, high temperature stability is outstanding.
Corrosion resistance
Seawater corrosion resistance:
Annual corrosion rate <0.005 mm, suitable for seawater desalination pipelines, ship condensers and so on.
Resistance to chloride ion pitting is 3 times that of ordinary copper alloy.
Resistant to chemical media:
Resistant to pH 3-11 acid and alkali solutions.
No stress corrosion tendency in sulfur-containing and ammonia environment.
High-temperature oxidation resistance: oxidation rate below 800 ≤ 0.1 mm/year.
V. Processing and heat treatment
Cold working: 80% of the maximum allowable deformation, need to anneal in stages to avoid cracking.
Annealing process:
Temperature 780-810 to eliminate internal stress and restore plasticity.
Rapid cooling may cause surface oxidation.
Welding performance: support TIG, MIG welding, qualified rate ≥95%.
Surface treatment: Electroplating, chemical plating or spraying anti-corrosion coating is available.
VI. Typical application areas
Marine engineering:
Desalination system piping
Ship condenser, pump and valve components
Chemical equipment:
Reactor lining, acid and alkali transfer pumps
Heat exchanger tube bundle (high temperature and high pressure resistance)
Energy power:
Nuclear power plant cooling lines
Transformer heat sinks (both conductive and corrosion resistant)
Aerospace:
Engine high-temperature fasteners (to be combined with surface treatment)
Fuel lines (low-temperature propellant resistance)
VII. Industry standards and selection recommendations
International standards:
ASTM: B370 (pipe), B122 (forgings)
