UNS C91300 (Alloy A) Bell Metal
C91300 bell metal is a bronze formulated for casting. Cited properties are appropriate for the as-fabricated (no temper or treatment) condition. C91300 is the UNS number for this material. Additionally, the common industry name is 81-19 Tin Bronze.
It has the highest base cost among cast bronzes. In addition, it has the lowest ductility and the highest embodied energy.
The graph bars on the material properties cards below compare C91300 bell metal 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
190 MPa 27 x 103 psi
Elastic (Young's, Tensile) Modulus
100 GPa 15 x 106 psi
Elongation at Break
0.5 %
Poisson's Ratio
0.34
Shear Modulus
38 GPa 5.5 x 106 psi
Tensile Strength: Ultimate (UTS)
240 MPa 35 x 103 psi
Tensile Strength: Yield (Proof)
210 MPa 30 x 103 psi
Thermal Properties
Latent Heat of Fusion
180 J/g
Maximum Temperature: Mechanical
150 °C 300 °F
Melting Completion (Liquidus)
890 °C 1630 °F
Melting Onset (Solidus)
820 °C 1500 °F
Specific Heat Capacity
360 J/kg-K 0.085 BTU/lb-°F
Thermal Expansion
18 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
7.0 % IACS
Electrical Conductivity: Equal Weight (Specific)
7.4 % IACS
Otherwise Unclassified Properties
Base Metal Price
39 % relative
Density
8.6 g/cm3 530 lb/ft3
Embodied Carbon
4.5 kg CO2/kg material
Embodied Energy
74 MJ/kg 32 x 103 BTU/lb
Embodied Water
460 L/kg 54 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
1.1 MJ/m3
Resilience: Unit (Modulus of Resilience)
210 kJ/m3
Stiffness to Weight: Axial
6.6 points
Stiffness to Weight: Bending
18 points
Strength to Weight: Axial
7.8 points
Strength to Weight: Bending
10 points
Thermal Shock Resistance
9.3 points
Alloy Composition
Among cast copper alloys, the composition of C91300 bell metal 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.
| Cu | 79 to 82 | |
| Sn | 18 to 20 | |
| P | 0 to 1.5 | |
| Ni | 0 to 0.5 | |
| Fe | 0 to 0.25 | |
| Pb | 0 to 0.25 | |
| Zn | 0 to 0.25 | |
| Sb | 0 to 0.2 | |
| S | 0 to 0.050 | |
| Si | 0 to 0.0050 | |
| Al | 0 to 0.0050 | |
| res. | 0 to 0.6 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM B22: Standard Specification for Bronze Castings for Bridges and Turntables
ASM Specialty Handbook: Copper and Copper Alloys, J. R. Davis (editor), 2001
CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015