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UNS C93700 Leaded Tin Bronze

C93700 bronze is a bronze formulated for casting. Cited properties are appropriate for the as-fabricated (no temper or treatment) condition. C93700 is the UNS number for this material. Additionally, the common industry name is 80-10-10. Older literature may refer to this material as ASTM Alloy 3A, Alloy C, or SAE 64.

It has a very low melting temperature among cast bronzes. In addition, it has a fairly low heat capacity and a moderately low tensile strength.

The graph bars on the material properties cards below compare C93700 bronze to: cast bronzes (top), all copper alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

Mechanical Properties

Compressive (Crushing) Strength

210 MPa 30 x 103 psi

Elastic (Young's, Tensile) Modulus

99 GPa 14 x 106 psi

Elongation at Break

20 %

Fatigue Strength

90 MPa 13 x 103 psi

Impact Strength: V-Notched Charpy

15 J 11 ft-lb

Poisson's Ratio


Rockwell B Hardness


Shear Modulus

37 GPa 5.3 x 106 psi

Tensile Strength: Ultimate (UTS)

240 MPa 35 x 103 psi

Tensile Strength: Yield (Proof)

130 MPa 18 x 103 psi

Thermal Properties

Latent Heat of Fusion

170 J/g

Maximum Temperature: Mechanical

140 °C 290 °F

Melting Completion (Liquidus)

930 °C 1710 °F

Melting Onset (Solidus)

760 °C 1400 °F

Solidification (Pattern Maker's) Shrinkage

1.1 %

Specific Heat Capacity

350 J/kg-K 0.083 BTU/lb-°F

Thermal Conductivity

47 W/m-K 27 BTU/h-ft-°F

Thermal Expansion

19 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

10 % IACS

Electrical Conductivity: Equal Weight (Specific)

10 % IACS

Otherwise Unclassified Properties

Base Metal Price

33 % relative


8.9 g/cm3 560 lb/ft3

Embodied Carbon

3.5 kg CO2/kg material

Embodied Energy

57 MJ/kg 24 x 103 BTU/lb

Embodied Water

390 L/kg 47 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

40 MJ/m3

Resilience: Unit (Modulus of Resilience)

79 kJ/m3

Stiffness to Weight: Axial

6.2 points

Stiffness to Weight: Bending

17 points

Strength to Weight: Axial

7.5 points

Strength to Weight: Bending

9.6 points

Thermal Diffusivity

15 mm2/s

Thermal Shock Resistance

9.4 points

Alloy Composition

Among cast copper alloys, the composition of C93700 bronze is notable for containing a comparatively high amount of lead (Pb). Lead is used to improve machinability and bearing properties, at the cost of toxicity. It also adds pressure tightness to castings.

Copper (Cu)Cu 78 to 82
Tin (Sn)Sn 9.0 to 11
Lead (Pb)Pb 8.0 to 11
Phosphorus (P)P 0 to 1.5
Nickel (Ni)Ni 0 to 1.0
Zinc (Zn)Zn 0 to 0.8
Antimony (Sb)Sb 0 to 0.5
Iron (Fe)Fe 0 to 0.15
Sulfur (S)S 0 to 0.080
Silicon (Si)Si 0 to 0.0050
Aluminum (Al)Al 0 to 0.0050
Residualsres. 0 to 1.0

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

Copper: Its Trade, Manufacture, Use, and Environmental Status, Gunter Joseph, 2001

Properties and Selection: Nonferrous Alloys and Special-Purpose Materials, ASM Handbook vol. 2, ASM International, 1993