C38500

C38500, also known as Architectural Bronze or UNS C38500, is a free cutting brass alloy with enhanced machinability and good corrosion resistance. It is a significantly improved form of 60/40 brass, containing slightly less copper and added lead for better machining performance. This alloy is used extensively for mass production of brass components on high-speed lathes, where maximum output and longest tool life are required. It does not require further cold forming after machining.

Chemical Composition

• Copper (Cu): 55.0 - 59.0%

• Lead (Pb): 2.5 - 3.5%

• Iron (Fe): Up to 0.35%

• Zinc (Zn): Remainder (balance)

• Total Others: Up to 0.5%

Mechanical Properties (Typical for temper HO2)

• Tensile Strength: 340 - 380 MPa

• Proof Stress: 130 MPa (minimum)

• Elongation: About 12%

• Hardness (Brinell): 50 - 75 HB

Physical Properties

• Density: Approximately 8.47 g/cm³

• Electrical Conductivity: 28% IACS at 68°F (20°C)

• Thermal Conductivity: 71 BTU/(ft²·hr·°F) at 68°F

• Melting Point: Solidus ~1610°F (872°C); Liquidus ~1630°F (888°C)

• Coefficient of Thermal Expansion: About 11.6 x 10⁻⁶ per °F (68°F to 572°F)

Fabrication and Machinability

• Machinability rating: 90 (excellent)

• Good for soldering and brazing

• Welding is generally not recommended

• Excellent hot workability; poor cold workability

Typical Applications

• Architectural millwork

• Decorative hardware

• Precision machined components

• Industrial machinery parts

• Fasteners and fittings