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Bronze typically refers to a family of alloys with copper as the base, primarily alloyed with elements such as tin, aluminum, silicon, and manganese. Compared to brass (copper-zinc alloys), bronze generally offers higher strength, a lower coefficient of friction, and better chemical corrosion resistance (especially against seawater). Its outstanding wear resistance and self-lubricating properties make it irreplaceable in bearing and bushing applications.
1. C93200 / SAE 660 (High-Leaded Tin Bronze - Bearing Bronze)
Most Widely Used Bearing Bronze● Characteristics: This is the most widely used bearing bronze. The added lead forms soft particles within the alloy, providing excellent self-lubricating and anti-galling properties, making it ideal for operation under insufficient lubrication or high-load, low-speed conditions. It is easy to machine and offers good wear resistance.
● Typical Applications: General-purpose bearings, bushings, thrust washers, pump components, low-load gears.
C93200 Typical Properties (As Sand-Cast)
| 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)
High Strength & Corrosion Resistant● Characteristics: A high-strength, high-hardness aluminum bronze. Its corrosion resistance, wear resistance, and fatigue strength are among the best of all bronzes, with performance comparable to many steels. It retains strength at elevated temperatures and offers excellent impact and cavitation resistance.
● Typical Applications: Heavy-duty bearings, gears, valve seats, pump housings, propellers and components for seawater use, chemical processing equipment.
C95400 Typical Properties (Heat-Treated Condition)
| 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)
Precision & Spring Applications● Characteristics: A tin bronze containing a small amount of phosphorus. Phosphorus increases the alloy's elastic limit, fatigue strength, and wear resistance. This material offers excellent spring properties, good wear and corrosion resistance, and is easily machined into precision parts.
● Typical Applications: Electrical connectors, springs, diaphragms, bellows, wear plates, precision gears.
C54400 Typical Properties (Cold Worked Condition)
| 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)
Chemical & Marine Grade● Characteristics: A bronze with excellent corrosion resistance, particularly outstanding in sulfuric acid and sulfate environments. It combines high strength, high corrosion resistance, and good formability and weldability, making it widely used in chemical and marine industries.
● Typical Applications: Chemical processing equipment components, heat exchanger tube sheets, marine fittings, pump valves, fasteners, welded structures.
Frequently Asked Questions (FAQ)
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What is the difference between bronze and brass?
Bronze is primarily a copper-tin alloy (often with aluminum, silicon, or manganese), while brass is a copper-zinc alloy. Bronze generally offers higher strength, better wear resistance, and superior corrosion resistance — especially in seawater — compared to brass.
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Which bronze alloy is best for bearing applications?
C93200 (SAE 660 / High-Leaded Tin Bronze) is the most widely used alloy for bearings and bushings. Its high lead content provides excellent self-lubrication and anti-galling properties, making it ideal for high-load, low-speed or poorly lubricated conditions.
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Which bronze alloy offers the highest strength?
C95400 (Aluminum Bronze) offers the highest strength among common bronze alloys, with tensile strength ranging from 620 to 760 MPa in heat-treated condition — comparable to many low-alloy steels. It also provides excellent hardness (170–210 HB) and outstanding wear resistance.
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What is phosphor bronze used for?
Phosphor bronze (C54400) is commonly used in applications requiring excellent spring properties, high fatigue strength, and good wear resistance. Typical uses include electrical connectors, springs, diaphragms, bellows, wear plates, and precision gears.
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Is C65500 High-Silicon Bronze suitable for marine environments?
Yes. C65500 High-Silicon Bronze is particularly well-suited for marine and chemical environments. It offers outstanding corrosion resistance — especially in sulfuric acid and sulfate conditions — combined with high strength, good formability, and excellent weldability.
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How do I choose the right bronze alloy grade for my application?
The choice depends on your specific requirements: use C93200 for general bearing and bushing needs with self-lubrication; choose C95400 for high-load structural or marine components requiring maximum strength; select C54400 for precision elastic or electrical parts; and opt for C65500 when superior corrosion resistance and weldability in chemical or marine environments are priorities.
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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