Bronze C932 bearing bronze
Name and designation
Section titled “Name and designation”Bronze C932, designated as UNS C93200 and also known as SAE 660, is a copper‑tin‑lead‑zinc alloy belonging to the family of bearing bronzes. It is normally supplied in the as‑cast condition and is noted for its excellent machinability, good wear resistance, and ability to sustain moderate loads. It is one of the most widely used leaded bronzes for the manufacture of bushings, bearings and friction‑loaded components.
Chemical composition
Section titled “Chemical composition”The nominal chemical composition of bronze C932 is as follows:
| Element | Content (%) |
|---|---|
| Copper (Cu) | 83,0 |
| Tin (Sn) | 7,0 |
| Lead (Pb) | 7,0 |
| Zinc (Zn) | 3,0 |
Physical and thermal properties
Section titled “Physical and thermal properties”| Property | SI Value | Imperial Value |
|---|---|---|
| Density at 20 °C | 8,93 g/cm³ | 0.323 lb/in³ |
| Melting range | 844 – 1000 °C | 1551 – 1832 °F |
| Thermal conductivity at 20 °C | ~61 W/(m·K) | ~35 Btu/(h·ft·°F) |
| Specific heat | ~0,38 kJ/(kg·K) | ~0,09 Btu/(lb·°F) |
| Coefficient of thermal expansion (20 – 300 °C) | 18,0 × 10⁻⁶ /°C | 10,0 × 10⁻⁶ /°F |
Mechanical properties
Section titled “Mechanical properties”Typical mechanical properties correspond to sand‑cast material (as‑cast condition):
| Property | SI | Imperial |
|---|---|---|
| Brinell hardness | 65 HB | 65 HB |
| Tensile strength (maximum) | 240 MPa | 34 800 psi |
| Yield strength (0,5 % offset) | 125 MPa | 18 100 psi |
| Elongation at break (in 50 mm) | 20 % | 20 % |
| Modulus of elasticity | 100 GPa | 14 500 ksi |
| Compressive strength (at 10 % permanent deformation) | 315 MPa | 45 700 psi |
| Izod impact strength | 8,0 J | 5,9 ft·lb |
| Fatigue strength (10⁸ cycles, rotating beam) | 110 MPa | 16 000 psi |
| Poisson’s ratio | 0,34 | 0,34 |
| Machinability | 70 % | 70 % |
Note: Machinability is expressed relative to free‑cutting brass C36000 (100 %).
Heat treatments
Section titled “Heat treatments”Bronze C932 does not respond to hardening heat treatment. It has a stress‑relief temperature of 260 °C (500 °F) and does not accept quenching or tempering.
Weldability
Section titled “Weldability”This bronze allows joining by soft soldering and brazing (soldering and brazing). Carbon‑arc, oxyacetylene, shielded metal‑arc, and gas‑shielded arc welding are not recommended because the presence of lead makes it difficult to obtain sound joints.
Machinability
Section titled “Machinability”The machinability index is 70 % relative to free‑cutting brass C36000. The chip is brittle, which facilitates good surface finishes at high cutting speeds.
Applications
Section titled “Applications”Thanks to its combination of mechanical strength, low friction and high machinability, bronze C932 is widely used in:
- Friction bearings and bushings.
- Bushings and wear plates.
- Pump and valve components.
- Low‑speed gears and rings.
- Guides and sliding elements in machine tools.
- Parts for the marine, railway and automotive industries.
Comparison with similar materials
Section titled “Comparison with similar materials”Compared to other bearing bronzes, C932 offers a very competitive balance:
- Compared to C836 (CuSn5Pb5Zn5): C932 contains more lead (7 % vs. 5 %), which improves conformability and machinability while maintaining similar strength.
- Compared to C937 (CuSn10Pb10): C932 has lower tin and lead contents, so it sacrifices some extreme load capacity but gains in machinability and economy.
- In relation to C938 (CuSn7Pb15): C932 has less lead and more zinc, offering higher hardness and compressive strength than high‑lead bronzes, at the cost of a slight reduction in embeddability.
In applications requiring good conformability, machinability and wear resistance under moderate loads, C932 is considered the «general purpose» bronze par excellence.
Equivalent designations and standards
Section titled “Equivalent designations and standards”Bronze C932 is supplied in accordance with the following specifications:
- ASTM B271
- ASTM B30
- ASTM B505
- ASTM B584
- ASTM B763
- QQ C390
- SAE 660
- SAE J461
- SAE J462
Frequently Asked Questions (FAQ)
Section titled “Frequently Asked Questions (FAQ)”What is the density of bronze C932?
Section titled “What is the density of bronze C932?”Bronze C932 has a density of 8,93 g/cm³ (0.323 lb/in³) at room temperature.
What tensile strength does it have in the as‑cast condition?
Section titled “What tensile strength does it have in the as‑cast condition?”The typical tensile strength is 240 MPa (34 800 psi), with a yield strength of 125 MPa (18 100 psi).
What is its Brinell hardness?
Section titled “What is its Brinell hardness?”The average Brinell hardness is 65 HB.
What machinability index does bronze C932 have?
Section titled “What machinability index does bronze C932 have?”It has a machinability index of 70 % relative to free‑cutting brass C36000.
What is the thermal conductivity of C932?
Section titled “What is the thermal conductivity of C932?”Approximately 61 W/(m·K), equivalent to 35 Btu/(h·ft·°F) at 20 °C.
Is it possible to weld this bronze?
Section titled “Is it possible to weld this bronze?”Arc welding in any of its variants is not recommended; however, it allows brazing and soldering.
References
Section titled “References”- azom.com: https://www.azom.com/article.aspx?ArticleID=6294
- engineeringtoolbox.com: https://www.engineeringtoolbox.com/
- steelnumber.com: https://www.steelnumber.com/en/steel_alloy_composition_eu.php?name_id=1356