CuSn4 Phosphor Bronze

Designation & Standards

Standard Designation: CuSn4 (Tin-Phosphor Bronze)
International Equivalents: ASTM C51000 (USA), EN CW453K (Europe), JIS C5101 (Japan)
Applicable Standards: GB/T 5231-2012 (Wrought Copper Alloys), ASTM B103 (US Strip), EN 12163 (European Standard)

Key Features

1. High Elasticity & Wear Resistance: Excellent fatigue resistance, ideal for springs, contacts, and high-frequency moving parts.

2. Superior Corrosion Resistance: Resists atmospheric, freshwater, and seawater corrosion (rate ≤0.01 mm/a); no stress corrosion cracking.

3. Good Workability: Suitable for cold/hot working, stamping, and welding; annealing required post-cold working.

4. Balanced Conductivity & Thermal Properties: Electrical conductivity ~15% IACS, thermal conductivity 75–85 W/(m·K), ideal for conductive and wear-resistant applications.

Product Forms & Specifications

Form	Specifications	Delivery Condition
Strip	Thickness: 0.1–2.0mm; Width: ≤600mm	Soft (M), Hard (H)
Rod	Diameter: 5–150mm; Length: 2000–6000mm	Drawn, Hot-rolled
Wire	Diameter: 0.1–12.0mm	Coiled or Straight
Tube	OD: 3–200mm; Wall Thickness: 0.5–20mm	Soft, Half-hard

Chemical Composition

Element	Cu	Sn	P	Pb	Total Impurities
Content (%)	Balance (≥95.3)	3.5–4.5	0.1–0.35	≤0.02	≤0.2

Physical Properties

Property	Value	Remarks
Density	8.8–8.9 g/cm³	High compactness for precision parts
Electrical Conductivity	~15% IACS	Meets industrial conductivity needs
Thermal Conductivity	75–85 W/(m·K)	Moderate heat dissipation
Thermal Expansion Coefficient	18.5×10⁻⁶/°C (20–200°C)	Excellent thermal stability
Melting Point	1000–1020°C	Moderate casting fluidity

Mechanical Properties

Property	Soft (M)	Hard (H04)
Tensile Strength (σb)	350–450 MPa	550–700 MPa
Elongation (δ10)	≥40%	≥3%
Hardness (HV)	80–150	160–220
Elastic Modulus	≥105 GPa	Critical for spring applications

Core Advantages

1. Superior Comprehensive Performance: Balances strength, elasticity, and corrosion resistance for demanding industrial use.

2. Long Service Life & Reliability: Exceptional fatigue resistance with over 1 million cycles.

3. Surface Treatment Compatibility: Supports nickel/silver plating, passivation, and functional coatings.

Applications

1. Electronics: Relay spring contacts, connector terminals, sensor reeds.

2. Machinery: Bearing bushings, gears, wear-resistant spacers.

3. Marine Engineering: Seawater valves, pump seals (with protective coatings).

4. Automotive: Fuel injection springs, brake system seals.

Processing Guidelines

1. Annealing: Post-cold working, anneal at 600–700°C to restore plasticity.

2. Welding: Use TIG welding or brazing; avoid tin oxidation-induced brittleness.

3. Machining: Cutting speed ≤60 m/min; use carbide tools and sulfur-based coolant.

4. Surface Treatment: Clean thoroughly before coating to ensure adhesion.

FAQ

Q1: How does CuSn4 differ from brass (e.g., H62)?

A1: CuSn4 offers superior corrosion resistance, elasticity, and wear resistance but at a higher cost.

Q2: Is CuSn4 suitable for seawater environments?

A2: Corrosion rate ≤0.01 mm/a in direct exposure, but long-term use requires nickel plating or coatings.

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

A3: Limit rolling reduction (single-pass ≤20%), stress-relieve before annealing, and ensure smooth rollers.

Standards Reference

Chemical Composition: GB/T 5231-2012, ASTM B103
Mechanical Properties: EN 12163, JIS H3270 (Japanese rods)
Processing: ISO 426-2 (International manufacturing standards)

Note: Data based on national standards and industry documentation. Actual parameters may vary slightly due to production processes. Refer to supplier test reports for exact specifications.

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