CW707R

CW707R, also known as CZ126 or Admiralty Brass, is an arsenical brass alloy with about 70% copper and 30% zinc. It contains a small addition of arsenic (~0.04%), which significantly improves corrosion resistance without compromising ductility and formability.

Chemical Composition

• Copper (Cu): 68.5% – 71.5%

• Zinc (Zn): Balance (~28.5% – 31.5%)

• Arsenic (As): 0.02% – 0.06%

• Lead (Pb): Up to 0.07%

• Iron (Fe): Up to 0.05%

• Other impurities: Up to 0.20%

Mechanical Properties

• Tensile Strength: Approximately 340 – 400 MPa

• Proof Stress: Minimum 130 MPa

• Elongation: Minimum 45%

• Hardness: Around 130 HB

Physical Properties

• Density: 8.55 g/cm³

• Electrical Conductivity: 28% IACS

• Thermal Conductivity: 120 W/m·K

• Coefficient of Thermal Expansion: 19.7 × 10⁻⁶ /°C

• Melting Range: 910 – 965 °C

Fabrication and Uses

• Outstanding corrosion resistance, particularly in warm, acidic, and subsea environments

• High strength and ductility with excellent cold working and formability

• Suitable for soldering and brazing; not recommended for welding

• Used predominantly in heat exchangers, condensers, chemical processing equipment, steam turbines, and marine applications

• Exhibits good machinability with a rating approx. 25% relative to free-cutting brass (CuZn39Pb3)