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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)
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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.
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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)
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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.
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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)
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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.
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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)
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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.
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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 (FAQ)
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What is the most commonly used bronze grade for bearings and bushings?
C93200 (SAE 660), also known as High-Leaded Tin Bronze or Bearing Bronze, is the most widely used grade for bearings and bushings. Its high lead content provides exceptional self-lubrication and anti-galling properties, making it ideal for high-load, low-speed, and poorly lubricated operating conditions.
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What makes C95400 Aluminum Bronze stand out compared to other bronze alloys?
C95400 Aluminum Bronze offers some of the highest strength and hardness among all bronze alloys, with tensile strength reaching 620–760 MPa—comparable to many low-alloy steels. It also provides outstanding corrosion resistance (especially in seawater), excellent fatigue strength, and good performance at elevated temperatures, making it suitable for heavy-duty marine and industrial applications.
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Why is phosphorus added to C54400 Phosphor Bronze?
Phosphorus serves two key roles in C54400: it acts as a deoxidizer during casting to improve alloy purity, and it significantly enhances the material's elastic limit, fatigue strength, and wear resistance. This makes Phosphor Bronze particularly well-suited for springs, electrical connectors, and precision components that require high resilience and durability.
Q
Which bronze alloy is best suited for use in seawater or marine environments?
Both C95400 (Aluminum Bronze) and C65500 (High-Silicon Bronze) perform excellently in marine environments. C95400 is favored for structural and mechanical parts such as marine propellers and pump housings due to its high strength and cavitation resistance. C65500 is preferred where superior corrosion resistance in chemical or saltwater environments is the primary concern, along with good weldability for fabricated structures.
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Can these bronze alloys be CNC machined into complex or precision parts?
Yes. All four bronze grades listed—C93200, C95400, C54400, and C65500—are compatible with CNC machining processes. C93200 and C54400 offer particularly good machinability. Our machining centers are equipped to handle complex geometries and tight tolerances, supporting everything from prototype development to small-batch precision manufacturing across all these materials.
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How do I choose the right bronze alloy grade for my application?
Choosing the right bronze grade depends on your specific operating requirements:
• C93200 – Best for general bearings and bushings under moderate loads with limited lubrication.
• C95400 – Ideal when high strength, hardness, and corrosion resistance are critical (e.g., heavy-duty gears, marine parts).
• C54400 – Recommended for spring elements, electrical connectors, and precision wear components.
• C65500 – Choose for chemical processing or marine environments where weldability and corrosion resistance are priorities.
If you are unsure which grade best suits your project, feel free to contact our engineering team for a material consultation.
• C93200 – Best for general bearings and bushings under moderate loads with limited lubrication.
• C95400 – Ideal when high strength, hardness, and corrosion resistance are critical (e.g., heavy-duty gears, marine parts).
• C54400 – Recommended for spring elements, electrical connectors, and precision wear components.
• C65500 – Choose for chemical processing or marine environments where weldability and corrosion resistance are priorities.
If you are unsure which grade best suits your project, feel free to contact our engineering team for a material consultation.
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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