C28500

C28500 is a lead-free brass alloy also known as Muntz Metal or UNS C28500, with copper content between 57-59% and zinc as the balance. It is valued for its machinability and is often used as a cost-effective replacement for leaded brass in applications where high mechanical properties and corrosion resistance are not critical.

Chemical Composition

• Copper (Cu): 57.0% – 59.0%

• Lead (Pb): Up to 0.25%

• Iron (Fe): Up to 0.35%

• Zinc (Zn): Remainder

• Other elements: Up to 0.90% max total impurities

Mechanical Properties

• Tensile Strength (UTS): Ranges from 410 MPa to 480 MPa depending on diameter and form

• Proof Stress: 180 MPa to 300 MPa depending on size

• Elongation: Minimum 8% to 18% depending on size and form

• Hardness: Not explicitly specified but typical for brasses in this range

Physical Properties

• Melting point (solidus): 1630 °F (885 °C)

• Melting point (liquidus): 1650 °F (900 °C)

• Density: 8.39 g/cm³

• Electrical Conductivity: About 29% IACS

• Thermal Conductivity: 58 BTU/sq ft/ft/hr/°F at 68°F

• Coefficient of Thermal Expansion: 11 x 10⁻⁶ per °F (68-212°F)

Fabrication and Uses

• Excellent for soldering and brazing

• Good oxyacetylene welding; fair for gas shielded arc welding

• Not recommended for coated metal arc welding and seam welding

• Good spot-weld and butt-weld capabilities

• Fair capacity for cold working; excellent capacity for hot forming

• Forgeability rating: 100

• Machinability rating: 60%

Typical Uses

• Fasteners and general industrial applications

• Components requiring moderate machinability without lead addition

• Suitable for use in environments where reduced lead content is required