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Common Bronze Alloy Grades and Characteristics
Bronze generally refers to a group of copper‑based alloys, mainly alloyed with tin, aluminum, silicon, manganese, and other elements. Compared with brass (copper‑zinc alloys), bronze typically features higher strength, a lower friction coefficient, and better chemical corrosion resistance—especially in seawater environments. Thanks to its excellent wear resistance and self‑lubricating properties, it plays an irreplaceable role in bearings and bushings. Our machining centers are well‑equipped to process various bronze materials, supporting high‑quality production from complex prototypes to small‑batch manufacturing.
1. C93200 / SAE 660 — High-Leaded Tin Bronze (Bearing Bronze)
Characteristics: This is the most commonly used bearing bronze grade. Lead is added to form soft particles in the alloy structure, delivering exceptional self-lubrication and anti-galling performance. This makes it particularly suitable for applications with insufficient lubrication, or under high-load and low-speed operating conditions. It features good machinability and reliable wear resistance.
Typical Applications: Suitable for general‑purpose bearings, bushings, thrust washers, pump components, and low‑load gears across various industrial applications.
| Property | Value | Notes |
| Tensile Strength (MPa) | 240 – 330 | Good overall strength |
| Yield Strength (0.5% Extension, MPa) | 124 | |
| Elongation at Break (%) | 18 | Good ductility |
| Hardness (Brinell) | 65 | |
| Density (g/cm³) | 8.93 | |
| Key Composition | Cu-83%, Sn-7%, Pb-7%, Zn-3% | High lead content provides self-lubrication |
ⓘ Note: Values are typical ranges, specific to casting and processing conditions.
2. C95400 — Aluminum Bronze
Characteristics: This is a high‑strength, high‑hardness aluminum bronze. It boasts some of the best corrosion resistance, wear resistance, and fatigue strength among all bronze alloys, with performance comparable to many steel materials. It maintains its strength at elevated temperatures and delivers excellent resistance to impact and cavitation.
Typical Applications: Ideal for heavy-duty bearings, gears, valve seats, pump housings, marine propellers and seawater-resistant components, as well as various parts used in chemical processing equipment.
| Property | Value | Notes |
| Tensile Strength (MPa) | 620 – 760 | Very high strength, comparable to low-alloy steels |
| Yield Strength (0.2% Offset, MPa) | 275 | |
| Elongation at Break (%) | 12 – 18 | |
| Hardness (Brinell) | 170 – 210 | High hardness, very wear-resistant |
| Density (g/cm³) | 7.45 | Lighter than tin bronze |
| Key Composition | Cu-85%, Al-11%, Fe-4% | Tin-free, uses aluminum and iron as main alloying elements |
ⓘ Note: Values are typical ranges, specific to heat treatment condition.
3. C54400 — Phosphor Bronze
Characteristics: This is a tin bronze with a small addition of phosphorus. Phosphorus enhances the alloy's elastic limit, fatigue strength, and wear resistance. The material exhibits excellent spring characteristics, good wear and corrosion resistance, and can be readily machined into precision components.
Typical Applications: Perfect for electrical connectors, springs, diaphragms, bellows, wear plates, and high-precision gears across multiple industrial applications.
| Property | Value | Notes |
| Tensile Strength (MPa) | 520 – 690 | High strength, especially suitable for elastic elements |
| Yield Strength (0.2% Offset, MPa) | 380 – 550 | High yield strength |
| Elongation at Break (%) | 10 – 15 | |
| Hardness (Rockwell B) | 78 – 90 | |
| Density (g/cm³) | 8.8 | |
| Key Composition | Cu-88%, Sn-4%, Zn-4%, P-0.2–0.5% | Phosphorus acts as a deoxidizer and enhances properties |
ⓘ Note: Values are typical ranges, specific to the degree of cold work.
4. C65500 — High-Silicon Bronze
Characteristics: This bronze features exceptional corrosion resistance, especially in sulfuric acid and sulfate environments. It combines high strength, excellent corrosion resistance, good formability and weldability, making it widely applied in the chemical and marine industries.
Typical Applications: Ideal for components in chemical processing equipment, heat exchanger tube sheets, marine hardware and fittings, pump and valve parts, fasteners, as well as welded structural parts.
Frequently Asked Questions
Q
What is the main difference between C93200 and C95400 bronze?
C93200 (SAE 660) is a high-leaded tin bronze primarily valued for its self-lubricating properties and suitability under low-speed, high-load, or poorly lubricated conditions. C95400 is an aluminum bronze that offers significantly higher strength, hardness, and corrosion resistance, making it suitable for heavy-duty structural and marine applications where mechanical performance is the priority.
Q
Why is phosphorus added to C54400 bronze?
Phosphorus serves two key roles in C54400 (Phosphor Bronze): it acts as a deoxidizer during casting, improving the quality and integrity of the alloy, and it significantly enhances the material's elastic limit, fatigue strength, and wear resistance. This makes C54400 particularly well-suited for spring contacts, precision gears, and other components that require both elasticity and durability.
Q
Which bronze alloy is best suited for seawater or marine environments?
Both C95400 (Aluminum Bronze) and C65500 (High-Silicon Bronze) perform well in marine environments. C95400 is widely used for marine propellers, pump housings, and seawater-resistant components due to its outstanding corrosion and cavitation resistance. C65500 is preferred when weldability and resistance to chemical corrosion (such as sulfuric acid) are also required alongside marine durability.
Q
Can these bronze alloys be used for CNC machining and precision manufacturing?
Yes. All four bronze grades listed are compatible with CNC machining. C93200 is particularly noted for its excellent machinability. C54400 can be machined into high-precision components. C95400 and C65500, while harder, can also be machined with appropriate tooling. Our machining centers are fully equipped to handle these materials from prototype to small-batch production.
Q
How does C65500 High-Silicon Bronze compare to other bronze grades in terms of weldability?
C65500 stands out among bronze alloys for its excellent weldability and formability. Unlike leaded bronzes (such as C93200), which are difficult to weld due to lead content, C65500 can be readily welded using standard methods. This makes it a preferred choice for fabricated or welded structural assemblies in chemical and marine industries.
Q
How do I choose the right bronze alloy grade for my application?
The selection depends on your specific operating conditions: choose C93200 for general bearings and bushings requiring self-lubrication; choose C95400 when high strength, hardness, and corrosion resistance comparable to steel are needed; choose C54400 for precision elastic components such as springs and electrical connectors; and choose C65500 when superior corrosion resistance in chemical environments combined with good weldability is required. Our engineering team can assist in selecting the optimal grade for your project.
Finishes and Post-Processing Options
The zinc alloy substrate is highly suitable for various surface treatments to enhance decoration, protection, or functionality:
Electroplating: Such as chrome, nickel, gold, or silver plating, providing a highly decorative appearance, excellent wear and corrosion resistance. This is the most common choice.
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Passivation or Chromate Conversion Coating:
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Powder Coating:
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Painting:
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Physical Vapor Deposition (PVD):
Design and Machining Considerations
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Process Selection:
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Design Considerations:
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Material Selection:
Zamak 3 and 5 are suitable for the vast majority of general-purpose parts requiring good appearance and strength; ZA-8 is better for wear and bearing applications; for making rapid tooling, choose specialized alloys like Kirksite.
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