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Code

Copper

C7701 Copper

Grade Designation & Standards

Standard Grade: C7701 (Zinc White Copper/Nickel Silver)

International Equivalents:

China GB/T: BZn18-18

USA ASTM: C77000

Applicable Standards:

JIS: JIS H3110-2018 (Nickel Silver Sheets, Plates, and Strips)

Other References: GB/T 1176-1987, ASTM B122

Key Features

1. High Corrosion Resistance: Excellent performance in seawater, salt spray, and humid environments (corrosion rate ≤0.01 mm/a), ideal for marine applications.

2. Superior Workability: Suitable for cold/hot working, stamping, and welding with smooth surface finish.

3. Balanced Mechanical Properties: Tensile strength up to 540–865 MPa (hard state) with elongation ≥3%, combining strength and plasticity.

4. Aesthetic Appeal: Silver-white metallic luster, widely used in decorative and precision components.

5. Electrical & Shielding Properties: Electrical conductivity ~5% IACS with radiation shielding capabilities.

Common Product Forms & Specifications

Product Form	Size Range	Delivery Condition
Rod	Diameter: 5–150 mm; Length: 1–6 m	Annealed (O), Cold-drawn (H)
Strip	Thickness: 0.1–5.0 mm; Width ≤600 mm	Annealed (O), Hard (H)
Plate	Thickness: 0.1–50 mm; Width ≤1200 mm	Half-hard (1/2H), Hard (H)
Tube	OD: 3–200 mm; Wall Thickness: 0.5–20 mm	Annealed, Half-hard
Wire	Diameter: 0.1–12 mm	Coiled or Straight
Note: Custom profiles available per JIS H3110 standards .

Chemical Composition

Element	Cu	Ni	Zn	Fe	Mn	Other Impurities
Content	53.0–58.0%	16.5–19.5%	Balance	0.5–1.5%	3.0–4.0%	≤1.5%（incl. Sn, Pb, etc.）
Typical impurities: Pb≤0.5%, Sn≤0.5%, Al≤1.0% .

Physical Properties

Property	Value	Remarks
Density	8.7–8.9 g/cm³	High structural stability
Melting Point	1170–1350°C	Suitable for casting and high-temperature processes
Electrical Conductivity	~5% IACS	Suitable for low-current applications
Thermal Conductivity	32–40 W/(m·K)	Moderate heat dissipation
Elastic Modulus	125 GPa	High rigidity for elastic components

Mechanical Properties

Property	Annealed (O)	Hard (H)	Extra-Hard (EH)
Tensile Strength (Rm)	≥375 MPa	630–735 MPa	705–805 MPa
Elongation (A50)	≥20%	≥4%	—
Hardness (HV)	80–120	170–210	190–240
Note: Data per JIS H3110. Hard state suits high-strength parts; EH state for extreme conditions.

Core Advantages

1. Marine-Grade Durability: Superior corrosion resistance in seawater, outperforming stainless steel.

2. High Strength-Ductility Balance: Tensile strength ≥630 MPa (hard state) with retained plasticity.

3. Surface Treatment Adaptability: Supports plating, polishing, and passivation for functional and decorative needs.

Product Applications

Electronics: Liquid crystal oscillator housings, potentiometer springs, EMI shielding.
Marine Engineering: Seawater pipelines, valves, ship components.
Medical Devices: Surgical tools, vascular stents (requires passivation).
Decorative Hardware: Tableware, musical instruments, architectural panels.

Processing Guidelines

1. Welding: Use TIG welding with nickel-based filler (e.g., ERCuNi); avoid zinc vaporization.

2. Machining: Carbide tools with sulfur-based coolant; cutting speed ≤80 m/min.

3. Heat Treatment: Anneal at 700–750°C (stress relief), low-temperature annealing at 250°C.

Key Application Scenarios

High-Frequency Electronics: Crystal oscillator housings, connector terminals.
Deep-Sea Valves: High-pressure, corrosion-resistant valve components (hard state recommended).
Precision Instruments: Optical parts, springs, resistance wires.

FAQs

Q1: How does C7701 differ from C7521?

A1: C7521 has higher copper content (62–66%) with slightly lower corrosion resistance but better conductivity (6% IACS), suitable for general decoration and electronics.

Q2: Is C7701 suitable for acidic environments?

A2: Suitable for weak acids, but strong acids (e.g., concentrated sulfuric acid) require protective coatings to prevent stress corrosion cracking.

Q3: How to prevent edge cracking in cold-rolled strips?

A3: Limit rolling reduction to ≤20% per pass, anneal post-processing, and ensure smooth rollers.

Standard References

Chemical & Mechanical Properties: JIS H3110-2018, GB/T 1176-1987.
Processing: ASTM B543 (Cu-Ni Alloy Tubes).
Testing: ISO 6892-1 (Tensile Testing).

Note: This specification integrates JIS standards and industry data. Actual parameters may vary slightly due to manufacturing processes. Refer to supplier certifications for precise details.

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