C521 Bronze Alloy Wire (CuSn8)

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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.

Mechanical Properties

Round Wire

Temper Name  Temper Code  Tensile Strength (ksi) Mill Limits 
Min Max
Annealed   53 68 .0010 - .1285 inch
1/4 Hard H01 74 91
1/2 Hard H02 95 115
3/4 Hard H03 113 135
Hard H04 125 150

Square Wire

Temper Name  Temper Code  Tensile Strength (ksi) Mill Limits 
Min Max
Annealed   53 68 .0100 - .0808 inch
1/4 Hard H01 74 91
1/2 Hard H02 95 115
3/4 Hard H03 113 135
Hard H04 125 150

Rolled Flat

Temper Name  Temper Code  Tensile Strength (ksi) Mill Limits 
Min Max
Annealed   53 67

Thickness:
.0100 - .0500 inch

Width:
.0150 - .2500 inch

1/2 Half Hard H02 69 84
Hard H04 85 100
Extra Hard H06 97 112
Spring H08 105 119
Extra Spring H10 110 122

Physical Properties

Melting Point (Liquidis) 1880°F
Melting Point (Solidus) 1620°F
Density 0.318 lbs/cu in
Electrical Resistivity (Annealed) 79.8 ?(cir mil/ft) @ 68°F
Electrical Conductivity (Annealed) 13% IACS @ 68°F
Thermal Conductivity (Solutionized-Aged) 36 Btu ft/sq ft hr °F @ 68°F
Coefficient of Thermal Expansion 0.0000101°F (68-572°F)
Modulus of Elasticity (Tension) 16000 ksi
Modulus of Rigidity 6000 ksi