• Standard System: UNS (Unified Numbering System)

• Alloy Designation: C46400

• Common Name: Naval Brass, Naval Alloy Brass — emphasizing its primary application in seawater corrosion resistance.

• Alloy Type: Cu-Zn-Sn alloy (Copper-Zinc-Tin Brass), categorized as special brass or high-strength brass.

• Key Feature: Tin addition on top of standard Cu-Zn brass structure, dramatically improving corrosion resistance (especially against dezincification) and strength in seawater environments.

2. Chemical Composition
Copper: 59.0% - 62.0%
Zinc: Balance (approx. 36.7% - 39.0%)
Tin: 0.5% - 1.0% (optimal at 0.7% - 1.0%)
Lead: ≤ 0.20% (enhances machinability but strictly controlled)
Iron: ≤ 0.10%
Total Others: ≤ 0.50% (Nickel ≤0.50%, Arsenic, Antimony, Bismuth, Phosphorus, Sulfur in trace amounts)

• Why is Tin Critical?

Ordinary brass (C28000, C27000) is prone to dezincification in seawater — zinc selectively dissolves, leaving a porous, brittle copper skeleton. Tin contributes by:
(1) Forming a stable and dense protective oxide film on brass surfaces.
(2) Significantly suppressing zinc dissolution.
(3) Enhancing erosion resistance in flowing seawater.
(4) Providing solid solution strengthening for increased strength.

3. Key Properties
(1)Exceptional Corrosion Resistance:

Seawater Resistance: Core value of C46400, providing robust dezincification resistance.

Freshwater Resistance: Performs well.

Stress Corrosion Cracking (SCC) Resistance: Superior to many brasses in ammonia or mercury environments but requires stress control.

General Atmospheric Corrosion Resistance: Good.
Limitations: Poor resistance to strong acids, alkalis, sulfides, and stagnant seawater (prone to pitting). Performs better in high-flow seawater.

(2)Mechanical Properties:

High strength: Exceeds ordinary brasses (C27000/C28000), rivals some bronzes (C51000 Phosphor Bronze).

Good toughness and ductility: Endures impact and deformation well. Excellent annealed plasticity and high work-hardened strength.

(3)Typical Mechanical Values:

• Annealed:

Tensile Strength: ~380 - 450 MPa

Yield Strength (0.2% offset): ~140 - 170 MPa

Elongation: ≥45%

• Cold Worked (Drawn/Rolled):

Tensile Strength: 550 - 620 MPa

Yield Strength (0.2% offset): 480 - 550 MPa

Elongation: 10% - 20%

Shear Strength: 275 - 345 MPa (annealed) / 345 - 415 MPa (cold worked)

(4)Processing Properties:

Hot Workability: Excellent. Suitable for forging, extrusion, rolling (650°C - 800°C).

Cold Workability: Good. Supports cold rolling, drawing, bending, stamping.

Machinability: Good. Low lead content improves chip breaking and lubrication, providing 70-80% machinability of free-cutting brass (C36000).

(5)Welding & Brazing Performance:

Brazing: Excellent, primary joining method.

Soft Soldering: Good.

Fusion Welding: Difficult and not recommended due to zinc vaporization, leading to porosity, cracks, and reduced joint properties. If necessary, use TIG/MIG with specialized brass filler and strict heat control.

(6)Physical Properties:

Density: ~8.41 g/cm³ (lighter than steel, pure copper, and bronze)

Melting Point: Liquidus ~900°C, Solidus ~885°C

Electrical Conductivity: ~27% IACS

Thermal Conductivity: ~67 W/(m·K)

Coefficient of Thermal Expansion: ~20.8 µm/(m·K) (20-300°C)

Modulus of Elasticity: ~105 GPa

Color: Bright golden yellow (slightly darker than standard brass)

(7)Other Properties:

Non-magnetic

Moderate wear resistance

Antimicrobial effects due to copper-zinc composition

4. Comparison with Similar Alloys
(1)C27000 (65/35 Brass):

Lacks tin, lower cost, slightly better conductivity (~30% IACS).

Poor seawater corrosion resistance, prone to dezincification.

(2)C28000 (Muntz Metal):

No tin, higher strength than C27000, low cost.

Poor seawater resistance, used with protective coatings.

(3)C51000 (Phosphor Bronze):

Cu-Sn-P alloy.

Superior strength, elasticity, wear, fatigue resistance, excellent corrosion resistance.

Higher cost, less machinable than C46400.

(4)C63000 (Aluminum Bronze):

Cu-Al-Ni-Fe alloy.

Superior strength, hardness, wear, and corrosion resistance.

High cost, poor machinability.

(5)C68700 (Arsenical Aluminum Brass):

Cu-Zn-Al-As alloy.

Excellent resistance to stagnant seawater (arsenic inhibits dezincification).

Moderate strength, low conductivity.

Environmental considerations due to arsenic.

5. Main Applications
C46400 is widely used in:

(1)Shipbuilding & Marine Engineering:

Propellers for small to medium vessels.

Pump/valve housings, impellers, stems, flanges, fittings.

Shaft sleeves, bearings, couplings.

Deck hardware, fittings, railings, decorative components.

Seawater piping systems (brazed joints).

Condenser tube sheets (tubes often use copper-nickel or C68700).

(2)Power Industry:

Condenser tube sheets in thermal and nuclear power plants.

Components exposed to water vapor corrosion.

(3)General Machinery & Chemical Industry:

Components needing high corrosion resistance (pumps, valves, impellers).

Bushings, bearings under moderate loads.

Fixtures and fasteners in chemical equipment.

Wear plates, sliders.

(4)Construction & Structural Applications:

Coastal structures requiring marine atmosphere corrosion resistance.

Weather-resistant structural parts like bridge components.

(5)Others:

Musical instrument parts (horns, etc.).

Wear-resistant outdoor art and sculptures.

Precision-machined corrosion-resistant mechanical parts.

6. Common Product Forms

Bars: Primary form for machined parts (bushings, stems, fittings).

Forgings: Complex, high-strength components (propellers, valves, pump bodies).

Plates/Strips: Stamped parts, gaskets, wear plates, decorative panels.

Tubes: Seawater piping systems.

Wires: Brazing rods, rivets, limited springs.

Castings: Rare, with casting grades like C86400 for marine propellers.

7. Production & Processing Notes

Melting & Casting: Control tin uniformity, prevent zinc oxidation and volatilization.

Hot Working: Critical; precise temperature control (650-800°C) to avoid overheating.

Cold Working: Cold drawing/rolling enhances strength, moderate work hardening.

Heat Treatment: Mainly annealing to relieve stress.

Machining: Sharp tools, suitable cutting parameters, control lead dust risks.

8. Joining Methods

Preferred: Brazing with silver or copper-phosphorus filler metals.

Fusion welding: Use TIG/MIG with specialized brass wire, post-weld annealing.

Surface Treatment: Polishing, electroplating (nickel, chrome), passivation, or protective coatings.

9. Conclusion
C46400 (UNS) is a classic tin brass alloy, widely known as Naval Brass. Its key strengths lie in exceptional seawater corrosion resistance (especially dezincification), a balanced combination of strength and toughness, superior hot workability, and good machinability.

When you need a high-strength brass that operates reliably in brine/seawater environments, offers excellent forgeability and machinability, and is cost-effective, C46400 is a highly recommended choice.

10. About Suzhou Bolaibao Metal
Suzhou Bolaibao Metal Technology Co., Ltd. specializes in supplying high-performance copper alloys, stainless steels, and specialty metals. We are deeply engaged in shipbuilding, marine engineering, electronics, energy equipment, and precision manufacturing sectors, offering one-stop material solutions. With robust inventory, stable supply chains, and professional technical support, we ensure comprehensive material performance and product quality for our clients under demanding conditions.

Choose Bolaibao Metal for more reliable and professional material solutions, empowering your projects with superior durability, efficiency, and competitiveness.
Tel: +86 15366282159
Email: sale@bolaibao1.com
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