C87900 is a leaded tin bronze copper alloy with a nominal composition of approximately copper with 4% tin, 4% lead, and 2% zinc. This specialized casting alloy offers a balanced combination of medium strength (tensile strength ranging from 240 to 310 MPa) and good corrosion resistance in industrial environments. However, it possesses relatively low ductility and is not recommended for cold working or extensive forming operations; it is typically produced as cast plates or machined from cast slabs for subsequent use in finished components.
The alloy is primarily valued for three outstanding characteristics: excellent machinability due to the lead content acting as a chip-breaker, good wear resistance and anti-friction behavior under sliding contact, and superior pressure tightness that prevents leakage in fluid-handling systems. These attributes make C87900 copper plate an ideal material choice for manufacturing valve bodies, pump parts, pipe fittings, bearing cages, and other heavy-duty mechanical components that demand reliable sealing, low friction, and cost-effective machining in high-production volumes.
| Category | Specification Details |
|---|---|
| Alloy Type | Leaded Tin Bronze (Copper-based casting alloy) |
| UNS Number | C87900 |
| Forms Available | Thin sheets, plates, strips (cast and machined) |
| Cu | Balance (approx. 88–91%) |
| Sn | 3.5 – 4.5% |
| Pb | 3.5 – 4.5% |
| Zn | 1.5 – 3.0% |
| Fe | ≤ 0.15% |
| Sb | ≤ 0.25% |
| Other Impurities | ≤ 0.50% total |
| Density | 8.9 g/cm³ (0.322 lb/in³) |
| Melting Range | 850 – 980 °C (1560 – 1796 °F) |
| Thermal Conductivity | ~ 45 W/m·K (at 20°C) |
| Electrical Conductivity | ~ 12% IACS |
| Tensile Strength | 240 – 310 MPa (35 – 45 ksi) |
| Yield Strength (0.5% Ext.) | 120 – 170 MPa (17 – 25 ksi) |
| Elongation | 5 – 10% (in 50 mm) |
| Hardness | 75 – 90 HRB (Rockwell B) |
| Machinability Rating | 80% (relative to free-cutting brass = 100%) |
| Wear Resistance | Good (under sliding contact) |
| Pressure Tightness | Superior (leak-proof in hydraulic/pneumatic applications) |
| Corrosion Resistance | Good in industrial and atmospheric environments |
| Cold Workability | Poor (not recommended for cold forming) |
| Hot Workability | Fair |
| Typical Applications | Valve bodies, pump parts, pipe fittings, bearing cages, bushings, heavy-duty mechanical components |
| Standards | ASTM B584, SAE J461, SAE J462 |
