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UNS C90700 (SAE 65) Gear Bronze

C90700 bronze is a bronze formulated for casting. Cited properties are appropriate for the as-fabricated (no temper or treatment) condition. 65 is the SAE designation for this material. C90700 is the UNS number. Additionally, the common industry name is 89-11 Gear Bronze.

It has a moderately high base cost among cast bronzes. In addition, it has a moderately high thermal conductivity and a fairly high embodied energy.

The graph bars on the material properties cards below compare C90700 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

Brinell Hardness

90

Elastic (Young's, Tensile) Modulus

110 GPa 16 x 106 psi

Elongation at Break

12 %

Poisson's Ratio

0.34

Shear Modulus

40 GPa 5.8 x 106 psi

Tensile Strength: Ultimate (UTS)

330 MPa 48 x 103 psi

Tensile Strength: Yield (Proof)

180 MPa 26 x 103 psi

Thermal Properties

Latent Heat of Fusion

190 J/g

Maximum Temperature: Mechanical

170 °C 340 °F

Melting Completion (Liquidus)

1000 °C 1830 °F

Melting Onset (Solidus)

830 °C 1530 °F

Specific Heat Capacity

370 J/kg-K 0.088 BTU/lb-°F

Thermal Conductivity

71 W/m-K 41 BTU/h-ft-°F

Thermal Expansion

18 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

10 % IACS

Electrical Conductivity: Equal Weight (Specific)

10 % IACS

Otherwise Unclassified Properties

Base Metal Price

35 % relative

Density

8.7 g/cm3 540 lb/ft3

Embodied Carbon

3.7 kg CO2/kg material

Embodied Energy

60 MJ/kg 26 x 103 BTU/lb

Embodied Water

390 L/kg 47 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

34 MJ/m3

Resilience: Unit (Modulus of Resilience)

150 kJ/m3

Stiffness to Weight: Axial

6.9 points

Stiffness to Weight: Bending

18 points

Strength to Weight: Axial

10 points

Strength to Weight: Bending

12 points

Thermal Diffusivity

22 mm2/s

Thermal Shock Resistance

12 points

Alloy Composition

Among cast copper alloys, the composition of C90700 bronze is notable for containing a comparatively high amount of tin (Sn) and including sulfur (S). Tin is used to improve strength, bearing properties, and corrosion resistance against certain types of media. It also places certain constraints on cast part design, so as to avoid porosity problems. Sulfur is used to improve machinability at the cost of a decrease in electrical conductivity.

Copper (Cu) 88 to 90
Tin (Sn) 10 to 12
Phosphorus (P) 0 to 1.5
Nickel (Ni) 0 to 0.5
Lead (Pb) 0 to 0.5
Zinc (Zn) 0 to 0.5
Antimony (Sb) 0 to 0.2
Iron (Fe) 0 to 0.15
Sulfur (S) 0 to 0.050
Silicon (Si) 0 to 0.0050
Aluminum (Al) 0 to 0.0050
Residuals 0 to 0.6

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

Followup Questions

Similar Alloys

Further Reading

ASTM B427: Standard Specification for Gear Bronze Alloy Castings

ASTM B505: Standard Specification for Copper Alloy Continuous Castings

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

ASM Specialty Handbook: Copper and Copper Alloys, J. R. Davis (editor), 2001