Overview
Alloy C521 is a high tin alloy of the phosphor bronze family. The additional tin relative to the more commonly used C510 results in higher mechanical properties with a modest reduction in electrical conductivity. Applications include electronic parts, springs, contacts, switch parts and fasteners.
Physical Properties
| Annealing Range (Min) | 900 °F |
| Annealing Range (Max) | 1250 °F |
| Density | 0.318 lb/in³ |
| Electrical Resistivity (Annealed) | 79.8 Ω·cir-mil/ft @ 68 °F |
| Electrical Conductivity (Annealed) | 13% IACS @ 68 °F |
| Thermal Conductivity | 36 Btu/ft²/ft·hr/°F @ 68 °F |
| Coefficient of Thermal Expansion | 10.1 per °F (68-572 °F) |
| Modulus of Elasticity (Tension) | 16 ksi |
| Modulus of Rigidity (Tension) | 6 ksi |
| Melting Point (Solidus) | 1,700 °F |
| Melting Point (Liquidus) | 1,900 °F |
Round Wire
| TEMPER NAME | TEMPER CODE | TENSILE STRENGTH (ksi) |
MILL LIMITS (inch) |
|
| Min | Max | |||
| Annealed | 53.0 | 68.0 | .0010 - .1285 inch | |
| 1/4 Hard | H01 | 74.0 | 91.0 | |
| 1/2 Hard | H02 | 95.0 | 115 | |
| 3/4 Hard | H03 | 113 | 135 | |
| Hard | H04 | 125 | 150 | |
Square Wire
| TEMPER NAME | TEMPER CODE | TENSILE STRENGTH (ksi) |
MILL LIMITS (inch) |
|
| Min | Max | |||
| Annealed | 53.0 | 68.0 | .0100 - .0808 inch | |
| 1/4 Hard | H01 | 74.0 | 91.0 | |
| 1/2 Hard | H02 | 95.0 | 115 | |
| 3/4 Hard | H03 | 113 | 135 | |
| Hard | H04 | 125 | 150 | |
Rolled Flat
| TEMPER NAME | TEMPER CODE | TENSILE STRENGTH (ksi) |
MILL LIMITS (inch) |
|
| Min | Max | |||
| Annealed | 53.0 | 67.0 | Thickness: .0100 - .0500 inch Width: .0150 - .2500 inch |
|
| 1/2 Hard | H02 | 69.0 | 84.0 | |
| Hard | H04 | 85.0 | 100 | |
| Extra Hard | H06 | 97.0 | 112 | |
| Spring | H08 | 105 | 119 | |
| Extra Spring | H10 | 110 | 122 | |
