C959, or C95900, is a bronze alloy composed of 80-83% copper, 12-13.5% aluminum, and small proportions of iron and manganese. This grade of bronze is very hard (typically 241 to 286 BHN). It is strong, has high wear resistance, excellent corrosion resistance, and good anti-galling behavior, but suffers from low durability and impact resistance. Its hardness can be raised through solution heat treatment and aging.
Due to its high aluminum content, C959 is notable for its resistance to a wide range of acids and alkalis. It also has good resistance to petroleum products, and holds up especially well in marine environments.
Weldability is good, although it requires careful choice of electrodes. Machinability is poor at about a 20 rating out of 100; its hardness requires high cutting forces, while its brittleness makes it prone to chipping. For this reason, it’s important to purchase it in a form that minimizes machining.
| Property | Value | Notes |
|---|---|---|
| Material Type | Aluminum bronze | UNS C95900 |
| Composition | Cu 80-83%, Al 12-13.5%, Fe 3-5%, Mn 1.5%, Ni 0.5% | |
| Density | 7.06 g/cm3 | 0.255 lb/in3 |
| Melting Point | ~ 1,070-1,120 °C | ~ 1,958-2,048 °F |
| Hardness (Brinell) | ~ 241 | |
| Tensile Strength | ~ 620 MPa | ~ 90,000 psi |
| Yield Strength | ~ 345 MPa | ~ 50,000 psi |
| Elongation at Break | ~ 1-5 % | |
| Modulus of Elasticity | ~ GPa | ~ x106 psi |
| Thermal conductivity | ~ 494 BTU·in/(hr-ft²°F) | ~ 71.2 W/mK |
| Corrosion Resistance | Very good | Suitable for use with seawater |
| Magnetism | No | |
| Heat Treatment | Solution heat treat, then aging | May also be stress-relieved |
| Machinability | Low | |
| Weldability | Good | High risk of cracking |
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