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China Bronze CNC Machining Services - Reliable Supplier & Factory for High-Performance Industrial Parts
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)
- 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)
- 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)
- 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)
- 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
Q1
What is the main difference between C93200 and C95400 bronze?
C93200 (SAE 660) is a high-leaded tin bronze optimized for self-lubrication and ease of machining, making it the go-to choice for general-purpose bearings and bushings under moderate loads. C95400 is an aluminum bronze with significantly higher tensile strength (620–760 MPa vs. 240–330 MPa), greater hardness, and superior corrosion resistance, making it suited for heavy-duty structural and marine applications.
Q2
Why is lead added to C93200 bearing bronze?
Lead is insoluble in the copper matrix and forms discrete soft particles throughout the alloy. These particles act as a built-in solid lubricant, reducing friction and preventing metal-to-metal galling, especially when the external lubricant supply is insufficient. This makes C93200 particularly reliable in high-load, low-speed, or intermittently lubricated bearing applications.
Q3
What role does phosphorus play in C54400 phosphor bronze?
Phosphorus serves two key functions in C54400. First, it acts as a deoxidizer during melting, resulting in a cleaner, denser alloy with fewer casting defects. Second, even in small amounts (0.2–0.5%), phosphorus significantly raises the elastic limit and fatigue strength of the alloy, which is why phosphor bronze is widely used for springs, electrical connectors, and other components requiring reliable spring-back behavior over many cycles.
Q4
Is C95400 aluminum bronze suitable for seawater environments?
Yes. C95400 aluminum bronze forms a stable, adherent aluminum oxide film on its surface that provides excellent resistance to seawater corrosion, biofouling, and cavitation erosion. It is a preferred material for marine propellers, pump housings, valve seats, and other components exposed to seawater or brackish water service conditions.
Q5
What makes C65500 high-silicon bronze stand out for chemical industry use?
C65500 exhibits exceptional resistance to sulfuric acid, sulfates, and many other corrosive chemicals that would rapidly attack standard copper alloys or steel. Combined with its good weldability and formability, it can be fabricated into complex equipment such as heat exchanger tube sheets, pump valves, and welded vessel components — making it a practical and cost-effective choice for chemical processing environments.
Q6
How do I choose the right bronze alloy grade for my application?
The selection depends on several key factors: load and speed (C93200 excels in high-load, low-speed bearing conditions), strength requirements (C95400 is preferred when structural strength comparable to steel is needed), spring/electrical properties (C54400 phosphor bronze is ideal for precision elastic components), and corrosion environment (C65500 is best for chemical or marine exposure). Always cross-reference operating temperature, lubrication conditions, and regulatory requirements (e.g., RoHS restrictions on lead content) when making a final selection.
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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