C71000 Cupronickel (Thermal and Electrical Conductivity) Analysis

ASTM B111 Copper Tube PDF

C71000 Cupronickel (also known as Nickel Cupronickel) is an alloy primarily composed of copper (Cu) and nickel (Ni), and is a typical representative of cupronickel alloys. Its naming follows the US ASTM standard system, and its corresponding Chinese standard designation is BFe10-1-1 (GB/T 5231-2012). It has strong international compatibility. Due to its excellent corrosion resistance, moderate strength, and good processability, this material is widely used in marine engineering, chemical equipment, and the electronics industry.

The chemical composition of C71000 is based on a copper-nickel binary system, supplemented with small amounts of elements such as iron (Fe) and manganese (Mn) for performance optimization. The specific composition ranges are as follows (mass percentage):
Copper (Cu): Balance (typically ≥85%)
Nickel (Ni): 10.0%-11.0%
Iron (Fe): 1.0%-1.8%
Manganese (Mn): 0.5%-1.0%
Impurity Elements: The sum of lead (Pb) and zinc (Zn) should be ≤ 0.5%
Alloy Design Features:
The addition of nickel significantly improves corrosion resistance and provides solid solution strengthening; iron refines grains and enhances resistance to seawater erosion; and manganese improves deoxidation and enhances hot workability.

Mechanical Properties
Tensile Strength (Annealed): ≥275 MPa
Elongation (Annealed): ≥30%
Hardness (HV): 70-100
Strength can be increased to 450-600 MPa after cold work hardening, but plasticity is reduced.
Physical and Chemical Properties
Corrosion Resistance: Excellent performance in seawater, freshwater, and most acidic media, especially resistance to chloride stress corrosion cracking (SCC), suitable for long-term use in marine environments.
Thermal and Electrical Conductivity: Thermal conductivity is approximately 29 W/(m·K), and electrical conductivity is approximately 10% IACS (International Annealed Copper Standard), lower than pure copper but meeting general industrial requirements.
Cryogenic Performance: Maintains good toughness at -196°C, making it suitable for low-temperature engineering.
Processing Performance
Hot Working Temperature Range: 750-900°C, avoiding sulfur contamination.
It exhibits excellent cold working properties such as cold rolling, stamping, and bending, but requires intermediate annealing for stress relief. Excellent weldability, suitable for argon arc welding, brazing, and other methods.

Marine Engineering
Desalination system evaporators, ship condenser tube sheets, and seawater pump and valve components.
Offshore platform heat exchangers, with superior biofouling resistance compared to ordinary copper alloys.
Electronic and Electrical Industries
High-precision connectors and relay springs, balancing electrical conductivity and environmental corrosion resistance.
Electromagnetic shielding housings, used to protect electronic equipment in special environments.
Chemical and Energy Industries
Acidic medium transmission pipelines and flue gas desulfurization unit linings.
Auxiliary equipment for nuclear power plant cooling systems, with stable radiation oxidation resistance.
Other Industries
Architectural Decoration: Imitation silver appearance, commonly used in high-end door and window hardware.
Minting Industry: Some countries use it as coin blanks.

Smelting and Casting
Melt is melted in a medium-frequency induction furnace, with strictly controlled oxygen content. After casting into slabs, homogenization treatment is performed to eliminate segregation. Plastic Working
Hot Rolling: Initial rolling temperature 850-900°C, final rolling temperature no less than 600°C.
Cold Rolling: Multiple rolling passes with intermediate annealing (650-750°C) are used to achieve the target thickness.
Surface Treatment: Pickling (nitric acid-sulfuric acid mixture) to remove scale, polishing or passivation to improve surface quality.
Heat Treatment
Annealing is a critical step and must be performed in a protective atmosphere (such as nitrogen) to prevent oxidation and discoloration.

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As a professional enterprise dedicated to global copper product trade since 2008, GNEE Metal Group deeply recognizes the quality and responsibility embodied in the ASTM B111 standard. This standard not only specifies chemical composition and mechanical properties but also represents a comprehensive quality commitment spanning manufacturing processes to testing and verification. GNEE solemnly assures global customers that every ASTM B111-standard condenser tube and copper alloy tubing we supply will strictly adhere to its requirements for seamless manufacturing, annealing treatment, eddy current testing, and various mechanical performance tests. 

 

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