C544 phosphor bronze is a copper-zinc alloy containing 3-4% lead, 3.5-4.5% tin, iron, and a small amount (0.5%) of phosphorous. The addition of phosphorous improves wear and fatigue resistance, which makes this alloy a top choice for bearing and bushing applications. Phosphorous also reduces oxygen in the alloy, helping improve metal quality.
C544 bronze forms a protective patina in air, giving it good resistance to atmospheric corrosion. It also has excellent stress corrosion cracking resistance and, in harder tempers, has very high fatigue resistance.
C544 has good machinability and can be cold worked, soldered, and brazed. Cold working improves strength and hardness, and annealing after cold working further refines its properties. It is available in a wide range of tempers to suit specific application needs. High cutting speeds are possible, and the lead content ensures good chipping behavior. However, welding is not recommended as the lead can segregate and cause hot cracking.
| Property | Value | Notes |
|---|---|---|
| Material Type | Phosphor bronze | UNS C54400 |
| Density | 8.89 g/cm3 | 0.320 lb/in3 |
| Melting Point | ~ 927-999°C | ~ 1,700-1,830°F |
| Hardness (Brinell) | ~ 80-163 | Temper-dependent |
| Tensile Strength | ~ 303-517 MPa | ~ 43,900-75,000 psi |
| Yield Strength | ~ 131-434 MPa | ~ 19,000-62,900 psi |
| Elongation at Break | ~ 50% | |
| Modulus of Elasticity | ~ 117 GPa | ~ 17.0 x106 psi |
| Electrical Conductivity | 19% IACS at 68°F | |
| Thermal conductivity | ~50 BTU·in/(hr·ft²·°F) at 20°C | ~86.5 W/mK at 68°F |
| Corrosion Resistance | Good stress corrosion cracking resistance | |
| Good atmospheric resistance | Avoid exposure to moist ammonia and acetylene | |
| Magnetism | No | |
| Heat Treatment | Hardened through cold working, can be annealed afterwards | |
| Machinability | Good | Lead provides lubrication and good chip breaking |
| Weldability | Excellent solderability, can be brazed | Gas and arc; spot welding is not recommended |
| DFARS Compliance | No | Not qualified as a specialty steel under DFARS |
With decades of experience and strong mill relationships, we’re more than just a distributor—we’re your trusted partner. Let us help you find what others can’t.
