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UNS C93200 (SAE 660) Bearing Bronze

C93200 bronze is a bronze formulated for casting. Cited properties are appropriate for the as-fabricated (no temper or treatment) condition. 660 is the SAE designation for this material. C93200 is the UNS number. Additionally, the common industry name is 83-7-7-3. Older literature may refer to this material as ASTM Alloy 3B, but this is now discouraged.

It has a moderately low tensile strength among cast bronzes. In addition, it has a moderately low heat capacity and a moderately high ductility.

The graph bars on the material properties cards below compare C93200 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

320 MPa 46 x 103 psi

Elastic (Young's, Tensile) Modulus

100 GPa 15 x 106 psi

Elongation at Break

20 %

Fatigue Strength

110 MPa 16 x 103 psi

Poisson's Ratio


Rockwell B Hardness


Shear Modulus

38 GPa 5.5 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

180 J/g

Maximum Temperature: Mechanical

160 °C 310 °F

Melting Completion (Liquidus)

980 °C 1790 °F

Melting Onset (Solidus)

850 °C 1570 °F

Solidification (Pattern Maker's) Shrinkage

1.8 %

Specific Heat Capacity

360 J/kg-K 0.086 BTU/lb-°F

Thermal Conductivity

59 W/m-K 34 BTU/h-ft-°F

Thermal Expansion

18 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

12 % IACS

Electrical Conductivity: Equal Weight (Specific)

12 % IACS

Otherwise Unclassified Properties

Base Metal Price

32 % relative


8.8 g/cm3 550 lb/ft3

Embodied Carbon

3.2 kg CO2/kg material

Embodied Energy

52 MJ/kg 22 x 103 BTU/lb

Embodied Water

370 L/kg 44 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

40 MJ/m3

Resilience: Unit (Modulus of Resilience)

76 kJ/m3

Stiffness to Weight: Axial

6.5 points

Stiffness to Weight: Bending

18 points

Strength to Weight: Axial

7.5 points

Strength to Weight: Bending

9.7 points

Thermal Diffusivity

18 mm2/s

Thermal Shock Resistance

9.3 points

Alloy Composition

Among cast copper alloys, the composition of C93200 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 81 to 85
Lead (Pb)Pb 6.0 to 8.0
Tin (Sn)Sn 6.3 to 7.5
Zinc (Zn)Zn 2.0 to 4.0
Phosphorus (P)P 0 to 1.5
Nickel (Ni)Ni 0 to 1.0
Antimony (Sb)Sb 0 to 0.35
Iron (Fe)Fe 0 to 0.2
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