Bronze – Copper Casting Alloy (UNS C90300)

Bronze – copper casting alloy UNS C90300 is a cast alloy of copper-tin. Bronze is used in architecture for its attractive colour and longevity.

The following datasheet provides chemical composition and properties of UNS C90300 Bronze alloy.

Mechanical Properties

The mechanical properties of the UNS C90300 alloy are shown in the following table.

Hardness, Brinell7070
Tensile strength310 MPa45000 psi
Yield strength145 MPa21000 psi
Elongation at break30.00%30.00%


Continuous cast • Lion Metal™

Tin bronze alloys such as C90300 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. C90300 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.

C90300 Product description: Tin bronze

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

Building: heavy construction equipment
Fasteners: swivel
Industrial: bearings, bushings, gear blanks, gears, piston rings, pump bodies, pump impellers, valve bodies, valves
Plumbing: steam fittings

Chemical composition

Chemical composition according to ASTM B505/B505M-23
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 ratingDensity (lb/in3 at 68 °F)

Mechanical properties

Mechanical properties according to ASTM B505/B505M-23
Tensile strength, minYield strength, at 0.5% extension under load,, minElongation, in 2 in. or 50 mm minBrinell hardness (500 kg load)Remarks
ksiMPaksiMPa%typical BHN

Physical properties

Physical properties provided by CDA
US CustomaryMetric
Melting point – liquidus1832 °F1000 °C
Melting point – solidus1570 °F854 °C
Density0.318 lb/in3 at 68 °F8.80 gm/cm3 at 20 °C
Specific gravity8.88.8
Electrical conductivity12% IACS at 68 °F0.069 MegaSiemens/cm at 20 °C
Thermal conductivity43.2 Btu/sq ft/ft hr/°F at 68 °F74.8 W/m at 20 °C
Coefficient of thermal expansion 68-39210 · 10-6 per °F (68-392 °F)17.3 · 10-6 per °C (20-200 °C)
Specific heat capacity0.09 Btu/lb/°F at 68 °F377.1 J/kg at 20 °C
Modulus of elasticity in tension14000 ksi96527 MPa
Magnetic Permeability11

Fabrication properties

Fabrication properties provided by CDA
*Since brazing is performed within the hot-short range, strain must be avoided during brazing and cooling.
Oxyacetylene weldingFair
Gas shielded arc weldingFair
Coated metal arc weldingFair
Machinability rating30

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.