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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.
01 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.
02 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.
03 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.
04 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)
Q What is the difference between bronze and brass?
Bronze is primarily a copper-tin alloy (or copper alloyed with aluminum, silicon, etc.), while brass is a copper-zinc alloy. Bronze generally offers higher strength, a lower friction coefficient, and better corrosion resistance—particularly in seawater—compared to brass. Bronze is preferred for heavy-duty wear applications such as bearings and bushings.
Q Which bronze grade is best for bearing and bushing applications?
C93200 (SAE 660 / High-Leaded Tin Bronze) is the most widely used grade for bearings and bushings. Its high lead content creates soft particles within the alloy structure, providing exceptional self-lubrication and anti-galling performance—especially effective under high-load, low-speed, or insufficient lubrication conditions.
Q Is aluminum bronze (C95400) suitable for marine environments?
Yes. C95400 aluminum bronze is one of the best-performing alloys for marine applications. It offers outstanding corrosion resistance in seawater, excellent cavitation resistance, and high mechanical strength comparable to low-alloy steels. It is commonly used for marine propellers, pump housings, valve seats, and other seawater-exposed components.
Q What makes phosphor bronze (C54400) suitable for electrical connectors and springs?
The small addition of phosphorus in C54400 significantly enhances the alloy's elastic limit, fatigue strength, and wear resistance. This gives the material excellent spring characteristics—it can flex repeatedly without permanent deformation. Combined with good electrical conductivity and corrosion resistance, it is an ideal choice for electrical connectors, springs, diaphragms, and bellows.
Q Why is C65500 high-silicon bronze preferred in chemical processing environments?
C65500 high-silicon bronze offers exceptional resistance to sulfuric acid and sulfate environments, which are commonly encountered in chemical processing plants. Its combination of high strength, excellent corrosion resistance, good formability, and weldability makes it a reliable choice for heat exchanger tube sheets, pump and valve components, fasteners, and welded structural parts in demanding chemical and marine applications.
Q Can these bronze alloys be used for small-batch or prototype CNC machining?
Absolutely. All of the bronze grades listed—C93200, C95400, C54400, and C65500—are well-suited for CNC machining. Our machining centers are fully equipped to handle these materials, supporting everything from complex one-off prototypes to small and medium production runs. Each grade has good machinability, though tooling and cutting parameters may be adjusted based on hardness and alloy composition.
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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