1. Material Overview

C90700 belongs to the copper-based alloy category in the American UNS numbering system and is also known in the industry as Navy G Bronze. It is a tin bronze alloy with a variety of common forms, including castings, forgings, and bars, to meet the diverse needs of different industrial applications.

2. Chemical Composition Analysis

• Copper (Cu): 88.0–91.0%, providing excellent electrical and thermal conductivity as the base of the alloy.

• Tin (Sn): 7.0–9.0%, significantly improving hardness, wear resistance, and corrosion resistance.

• Zinc (Zn): ≤1.0%, enhancing the alloy's strength and corrosion resistance.

• Lead (Pb): ≤0.05%, improving the alloy's machinability.

• Iron (Fe): ≤0.20%, refining the grain structure, thus increasing strength and toughness.

• Nickel (Ni): ≤1.0%, improving corrosion resistance and heat resistance.

• Phosphorus (P): ≤0.05%, deoxidizing and improving the alloy's fluidity and density.

• Other Impurities: ≤0.50%, strictly controlled to ensure stable performance.

3. Mechanical Properties Analysis

At room temperature in the cast state, C90700 exhibits excellent mechanical properties:

• Tensile Strength: 275–345 MPa

• Yield Strength: 130–170 MPa

• Elongation: 10–20%

• Brinell Hardness (HB): 70–100

• Impact Toughness: Medium to high

• Through heat treatment processes such as annealing and aging, the performance of C90700 can be further optimized to meet more complex operational requirements.

4. Material Characteristics

（1）Corrosion Resistance
C90700 has exceptional resistance to seawater corrosion, making it the standard material for naval and shipbuilding industries. Its alloy composition can effectively resist pitting, crevice corrosion, and stress corrosion cracking, ensuring stable performance even in harsh marine environments.

（2）Wear Resistance
The addition of tin significantly enhances the alloy’s hardness and friction resistance, making C90700 especially suitable for manufacturing bearings, sliding surfaces, and other components. During friction and wear, a protective film forms on the surface of the alloy, effectively extending the service life of the components.

（3）Strength and Toughness
Among copper alloys, C90700 not only has relatively high strength but also possesses good ductility. This makes it highly resistant to impact and fatigue, allowing it to operate stably under complex stress conditions.

（4）Castability and Machinability
C90700 is well-suited for various casting methods, including sand casting, centrifugal casting, and precision casting. Additionally, it has excellent machinability, allowing for smooth turning, milling, drilling, and boring processes to meet the needs of complex component manufacturing.

5. Typical Applications

（1）Shipbuilding
C90700 is widely used in the shipbuilding industry, with applications ranging from propeller shaft sleeves, pump housings, valves, pipeline joints, to cooling system components.

（2）Construction Machinery
In the construction machinery sector, C90700 is commonly used for manufacturing heavy-load sliding bearings, bushings, gears, and worm gears. For example, the rotary support sliding bearings on excavators are made from C90700 to withstand massive pressure and friction, ensuring efficient operation.

（3）Electrical Industry
C90700 is widely used in the electrical industry for the manufacturing of conductive parts, switch components, and contactors due to its excellent electrical conductivity and corrosion resistance.

（4）Metallurgical Equipment
C90700 is used in metallurgical equipment for parts such as cooling water pipe interfaces and high-temperature lubricating components. It maintains stable performance in high-temperature, humid environments, ensuring the normal operation of equipment.

（5）Military Industry
In the military sector, C90700 is an important material for naval equipment and ship components, providing reliable material support for national defense.

6. Relevant Standards

• ASTM B584: Standard for cast copper alloys

• ASTM B505: Standard for continuous cast copper alloy bars

• SAE 65: Automotive engineering standard equivalent to C90700

• DIN/ISO: Corresponds to DIN 1705 Rg10, with specific component verification required

7. Comparison of C90700 with Other Copper Alloys

（1）Comparison with Brass (e.g., C26000)

①Composition Differences: Brass is primarily composed of Cu-Zn (zinc content 20-40%), whereas C90700 contains more tin (10%) and less zinc.

②Performance Features:

• Wear Resistance: C90700’s higher tin content enhances hardness (HB 70-90) and wear resistance significantly over brass.

• Corrosion Resistance: Both alloys resist atmospheric corrosion, but C90700 performs better in fresh water and steam environments.

• Machinability: Brass is easier to cold work, while C90700 is more suitable for casting.

③Applications: Brass is used for hardware components and radiators, while C90700 is used for pump bodies, valves, and bearings.

（2）Comparison with Phosphor Bronze (e.g., C51000)

①Composition Differences: Phosphor bronze contains tin (5-10%) and phosphorus (0.1-0.3%), while C90700 contains lead (2%).

②Performance Features:

• Strength and Elasticity: Phosphor bronze has a higher elastic limit (about 500MPa), suitable for springs, whereas C90700 has higher hardness but lower ductility.

• Self-lubrication: The lead content in C90700 improves machinability and self-lubrication, making it ideal for sliding parts.

③Applications: Phosphor bronze is used for electronic connectors, while C90700 is used for wear-resistant castings.

（3）Comparison with Aluminum Bronze (e.g., C61300)

①Composition Differences: Aluminum bronze contains aluminum (8-12%), while C90700 contains tin and lead.

②Performance Features:

• Strength and High-Temperature Resistance: Aluminum bronze has higher strength (σb≈650MPa) and better high-temperature resistance (above 300°C), but its castability is inferior.

• Wear Resistance: C90700 performs better under low-speed, heavy-load conditions, whereas aluminum bronze is more suited for high-speed, light-load applications.

③Applications: Aluminum bronze is used for gears and turbines, while C90700 is used for ship propellers and bearings.

（4）Core Advantages of C90700

• High Wear Resistance: The combination of tin and lead provides excellent wear resistance.

• Good Castability: The alloy has good fluidity, making it ideal for complex castings.

• Corrosion Resistance: It remains stable in freshwater, seawater, and weak acid environments.

• Cost-effectiveness: It is more economical than aluminum bronze and some high-performance alloys.

• Typical Applications: Marine parts, mechanical seals, pump impellers, bearing bushings, etc.

8. Suitable Environments and Precautions

• C90700 is suitable for humid, high-salt, high-load, and frequent friction conditions.

• However, it is not recommended for use in highly oxidative acid environments (such as concentrated nitric acid).

• In high-speed, high-temperature friction applications, caution should be exercised due to its limited thermal stability.

9. Summary of Advantages and Disadvantages of C90700

（1）Advantages:

• C90700 boasts exceptional corrosion resistance, especially in seawater environments.

• It has excellent wear and mechanical properties.

• Strong machinability for complex components.

• Stable material properties and high resistance to aging.

（2）Disadvantages:

• C90700 is more expensive than regular brass.

• It has a higher density (lighter than steel but heavier than aluminum).

• Performs poorly in strong acidic or alkaline environments.

We can process this alloy into round bars, plates, round pipes/square pipes, and coils according to your requirements.If you have any inquiries, please feel free to contact us. Our email address is: sale@bolaibao1.com. We look forward to your inquiry!