Introduction of tin bronze CuSn4

CuSn4 is tin bronze, which has high mechanical properties, corrosion resistance and high elasticity. It can be well processed under pressure in cold state, and can also be processed under pressure in hot state.

CUSN4 is widely used to make various pipe materials for pressure gauges.

  • Standards: GB/T 4423-1992
  • Features: Corrosion resistance and high elasticity
  • Grade: CuSn4

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Tin Bronze CuSn4 Description

CuSn4 is a solid solution strengthened copper alloy with 4% tin (bronze). It combines very good cold workability with high strength and hardness.

CuSn4 alloy is corrosion resistant and can be well soldered and brazed, yet it still has good electrical conductivity.

CuSn4 is used in applications where great importance is attached to the combination of conductivity and strength.

Fields of application are connectors, connector springs, springs and components of electrical and mechanical engineering.

Chemical Composition

Tin Bronze CuSn4

  • Cu: Allowance
  • Sn: 3.5 ~ 4.5
  • Pb: 0.02 or less
  • P: 0.20 ~ 0.40
  • Al: 0.002 or less
  • Fe: 0.02 or less
  • Si: 0.002 or less
  • Sb: 0.002 or less
  • Bi: 0.002 or less
  • Note: ≤0.1(impurity)

Mechanical Properties

  1. Tensile strength σb (MPa) : ≥410
  2. Elongation Δ10 (%) : ≥8
  3. Elongation Δ5 (%) : ≥10
  4. Note: Longitudinal tensile mechanical properties of bars at room temperature
  5. Sample size: diameter or opposite distance 5 ~ 12
  6. Heat treatment specification: thermal processing temperature 750 ~ 780℃; The annealing temperature is 600 ~ 650℃.
  7. Features: high strength, elasticity, wear resistance, diamagnetism, heat resistance, good machining performance, corrosion resistance and so on. Applications: Springs and precision instrument parts.

Main Applications

  1. Architecture: Bridge Bearing Plates.
  2. Electrical: Miniaturized Connectors, Contact Springs, Relais Springs, Terminals, Switch Parts Fuse Clips, Electronic Connectors
  3. Fasteners: Lock Washers, Fasteners.
  4. Industrial: Bellows, Textile Machinery, Perforated Sheets, Springs, Sleeve Bushing, Clutch Disks, Beater Bar, Chemical Hardware.
  5. General: Stamped parts, Connectors, Contact springs, Spring elements, Ultra high strength spring elements, Membranes, Switch elements, Fixed contacts.


CuSn4 provides an excellent combination of strength, excellent formability and hardness. It has a good electrical conductivity and corrosion resistance.

Soldering and brazing properties are excellent. We offer exceptionally narrow tolerances with regard to chemical composition,dimensional precision and mechanical properties.

Special characteristics such as superfine particle size or thermal-mechanical stress relieving improve mechanical properties and provide increased strength and greater malleability.

Alloy Designation

  • EN CuSn4
  • DIN CEN/TS 13388 CW450K
  • JIS C 5111
  • BS PB 101
  • UNS C51100

Fabrication Properties

  • Cold Forming Properties: Excellent
  • Hot Forming Properties(at 750 .. 850°C): Limited
  • Machinability (Rating 20): Less suitable
  • Electroplating Properties Excellent
  • Hot Tinning Properties: Excellent
  • Soft soldering, Brazing: Excellent
  • Resistance Welding: Good
  • Gas Shielded Arc: Welding Good
  • Laser Welding: Good
  • Soft Annealing: 450 .. 700°C
  • Stress Relieving Annealing: 200 .. 350°C

Corrosion Resistance

(1) Bronce is resistant to: Natural and industrial atmospheres as well as maritime air, drinking and service water (if the flow rate is not excessive), seawater, non oxidizing acids, alkaline solutions and neutral saline solutions.

(2) Bronce is not resistant to: Ammonia, halogenide, cyanide and hydrogen sulfide solutions and atmospheres, oxidizing acids.

(3) Bronce alloys have an improved resistivity towards seawater and pitting corrosion.