C3771

C3771 is a leaded alpha/beta brass alloy known as forging brass, specifically designed for hot forging applications. It contains a small addition of aluminium that imparts a bright golden colour. The lead content provides excellent machinability while maintaining good mechanical properties. C3771 is readily extrudable and used primarily in builder’s hardware and other forged parts requiring strength, durability, and good surface finish.

Chemical Composition

• Copper (Cu): 57.00 – 61.00%

• Lead (Pb): 1.00 – 2.50%

• Tin + Iron (Sn + Fe): Up to 1.00%

• Zinc (Zn): Balance (Remainder)

Mechanical Properties (Typical per JIS H3250, temper BD)

• Tensile Strength (UTS): Minimum 315 MPa

• Elongation: Minimum 15%

• Hardness: Not specified, but typically moderate

Physical Properties

• Density: Approximately 8.4 g/cm³

• Coefficient of Thermal Expansion (CTE): 14.4 µin/in-°F

• Specific Heat Capacity: 0.0908 BTU/lb-°F

• Thermal Conductivity: 784 BTU-in/hr-ft²-°F

• Melting Point: Solidus 1620°F, Liquidus 1650°F

Fabrication Properties

• Machinability Rating: Approximately 95% relative to CuZn39Pb3 (standard free-machining brass)

• Cold Workability: Poor

• Hot Workability: Excellent

Typical Applications

• Builder’s hardware

• Forged parts require good mechanical strength and machinability

• High-pressure valves and rotors