Continuous cast

Tin bronze alloys such as C91700 are typically found in gear and high-strength bushing and bearing applications where high strength, low speeds, and heavy loads are present. Other high-strength applications for these alloys are pump impellers, piston rings, steam fittings, and valve bodies. C917 tin bronze castings are utilized in movable bridge components, turntables for bridges, and other structures for fixed and expansion bearings with slow or intermittent movement and heavy loads.


Product description: High Tin Bronze
Solids: 1" to 6" O.D.
Tubes: 1" to 6" O.D.*
Rectangles: Up to 10"
Standard lengths: 144"
Shape/Form: semi-finished, mill stock or near-net shapes, anode, bar stock, billet/bloom, squares, hex, plate, profile or structural shape, flats/rectangular bar

 *Consult mill for wall thickness

Typical uses

Industrial: gears, heavy load/relatively low-speed bearings, worm gears, worm wheels

Similar or equivalent specification

CDA ASTM SAE AMS Federal Military Other
C91700 B427         Nickel Gear Bronze

Chemical composition

Cu%1 Pb% Sn% Zn% Fe% P% Ni%2 Al% S% Sb% Si%
Chemical composition according to ASTM B427-21

1In determining Cu min., Cu may be calculated as Cu + Ni.   2Ni value includes Co.
Note: Cu + sum of named elements, 99.4% min. Single values represent maximums.


Copper alloy UNS No. Machinability rating Density (lb/in3 at 68 °F)
C91700 20 0.316

Mechanical properties

Tensile strength, min Yield strength, at 0.5% extension under load,, min Elongation, in 2 in. or 50 mm min Brinell hardness (500 kg load) Remarks
ksi MPa ksi MPa % minimum BHN  
44 303 22 152 16 85
Mechanical properties according to ASTM ASTM B427-21

Physical properties

Physical properties provided by CDA
  US Customary Metric
Melting point - liquidus 1859 °F 1015 °C
Melting point - solidus 1563 °F 851 °C
Density 0.316 lb/in3 at 68 °F 8.75 gm/cm3 at 20 °C
Specific gravity 8.75 8.75
Electrical conductivity 10% IACS at 68 °F 0.058 MegaSiemens/cm at 20 °C
Thermal conductivity 40.8 Btu/sq ft/ft hr/°F at 68 °F 70.6 W/m at 20 °C
Coefficient of thermal expansion 68-392 9 · 10⁻⁶ per °F (68°-392 °F) 15.5 · 10⁻⁶ per °C (20-200 °C)
Specific heat capacity 0.09 Btu/lb/°F at 68 °F 377.1 J/kg at 20 °C
Modulus of elasticity in tension 15000 ksi 103400 MPa
Magnetic Permeability 1 1

Fabrication properties

Fabrication properties provided by CDA
*Since brazing is performed within the hot-short range, strain must be avoided during brazing and cooling.
Technique Suitability
Soldering Excellent
Brazing* Good
Oxyacetylene welding Fair
Gas shielded arc welding Fair
Coated metal arc welding Fair
Machinability rating 20

Thermal properties

Thermal properties provided by CDA
Temperature is measured in fahrenheit.   **For stress relief, Solution treatment and annealing - time is measured in hours/inch of thickness. For precipitation heat treatment - time is measured in hours.
Treatment Value* Time**
Stress relief 500  
Solution treatment   0

Find a product

Search by
CDA number