Gunmetal Admiralty Bronze Alloy (C90500 / LG2)
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Gunmetal Bronze (C90500 / LG2) | Bars, Bushes & Castings Brochure
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Descriptions
At Navkar Metal Syndicate, we specialize in supplying premium Gunmetal (Admiralty Bronze / C90500 / LG2) — a time-tested copper-based alloy composed primarily of copper, tin, zinc, and lead. Renowned for its superb strength, wear resistance, and corrosion protection, gunmetal is the preferred material for components exposed to steam, seawater, and mild chemical environments.
Our C90500 and LG2 grades are engineered to deliver excellent machinability, castability, and pressure tightness, ensuring reliable performance in valves, pumps, bearings, gears, plumbing parts, and marine hardware. With its natural lubricity and resistance to dezincification, gunmetal ensures long service life even under high loads and fluctuating pressures.
Every batch from Navkar Metal Syndicate is chemically analyzed, pressure tested, and supplied with complete Mill Test Certificates (MTCs), guaranteeing international compliance with ASTM B505 / B584, BS 1400 LG2, and IS 318. Designed for industrial, marine, and hydraulic applications, our gunmetal castings and rods combine heritage reliability with modern metallurgical precision — ensuring durability, performance, and trust that last decades.
Chemical Composition
Gunmetal (also known as Admiralty Bronze or LG2 Bronze) is a multi-element copper-based alloy combining copper, tin, zinc, and lead to achieve an ideal balance of strength, machinability, and corrosion resistance.
| Element | C90500 (%) | LG2 (%) |
|---|---|---|
| Copper (Cu) | 85.0 – 88.0 | 84.0 – 86.0 |
| Tin (Sn) | 4.0 – 6.0 | 4.0 – 6.0 |
| Zinc (Zn) | 4.0 – 6.0 | 4.0 – 6.0 |
| Lead (Pb) | 4.0 – 6.0 | 4.0 – 6.0 |
| Nickel (Ni) | ≤ 1.0 | ≤ 1.0 |
| Iron (Fe) | ≤ 0.30 | ≤ 0.30 |
| Phosphorus (P) | ≤ 0.05 | ≤ 0.05 |
| Other Elements (each) | ≤ 0.10 | ≤ 0.10 |
| Balance | Copper (Cu) | |
Note: Composition may vary slightly depending on casting process and standard (ASTM B505/B584, BS 1400 LG2, IS 318). All values are indicative typical ranges.
Mechanical, Physical & Fabrication Properties
Gunmetal (Admiralty Bronze / C90500 / LG2) offers a balance of strength, machinability, and corrosion resistance suitable for marine, hydraulic, and general engineering applications. Its inherent lubricity and castability make it ideal for pressure-tight and wear-prone components such as valves, pumps, and bearings.
| Property | Typical Value (C90500) | Typical Value (LG2) | Remarks |
|---|---|---|---|
| Tensile Strength | 200 – 300 MPa | 200 – 310 MPa | High strength for cast bronze alloys |
| Yield Strength (0.2% Proof) | 90 – 150 MPa | 90 – 160 MPa | Varies with casting method and temper |
| Elongation (% in 50 mm) | 10 – 20% | 10 – 20% | Good ductility for a cast alloy |
| Brinell Hardness (HB) | 70 – 100 HB | 70 – 110 HB | Moderate hardness with good machinability |
| Density | ≈ 8.8 g/cm³ | ≈ 8.8 g/cm³ | Typical for copper-based alloys |
| Melting Point | ≈ 1000 – 1050 °C | ≈ 1000 – 1050 °C | Dependent on Sn, Zn, and Pb content |
| Electrical Conductivity | 10 – 15% IACS | 10 – 15% IACS | Lower than pure copper due to alloying |
| Thermal Conductivity | ≈ 60 – 70 W/m·K | ≈ 60 – 70 W/m·K | Good for heat-transfer parts |
| Coefficient of Thermal Expansion | 17 × 10⁻⁶ /K | 17 × 10⁻⁶ /K | Stable under temperature changes |
| Machinability | Good | Good | Leaded composition improves cutting performance |
| Castability | Excellent | Excellent | Suitable for intricate and pressure-tight castings |
| Weldability | Fair | Fair | Brazing and soldering preferred |
| Corrosion Resistance | Excellent | Excellent | Highly resistant to seawater and mild chemicals |
Note: Mechanical properties may vary depending on casting type (sand, centrifugal, or continuous) and heat treatment. Typical standards: ASTM B505, B584, BS 1400 LG2, IS 318 Gr. 1.
Applications
Gunmetal, also known as Admiralty Bronze (C90500 / LG2), is widely used across marine, hydraulic, and industrial engineering sectors thanks to its exceptional corrosion resistance, castability, and wear performance. It performs reliably under high pressure, high load, and intermittent lubrication conditions.
- Valves, valve bodies, bonnets, and seats for steam and seawater service
- Pump casings, impellers, glands, and bearing bushes
- Marine hardware and fittings exposed to seawater and brine
- Hydraulic and pneumatic system components
- Gears, worm wheels, and heavy-duty bearing surfaces
- Plumbing and sanitary fittings for industrial and municipal systems
- Condenser end plates, cooling water fittings, and ship propeller hubs
- Pressure-tight castings and flanges for chemical and desalination plants
- Steam service castings and locomotive parts
- General engineering applications requiring high strength with good machinability
With its unique combination of mechanical strength, self-lubrication, and corrosion resistance, Gunmetal (C90500 / LG2) remains the alloy of choice for high-reliability components in marine, hydraulic, and general engineering industries.
Standards & International Equivalents:
Gunmetal, also known as Admiralty Bronze, conforms to multiple international specifications that define its composition, mechanical performance, and casting quality. These standards ensure consistency across global marine, hydraulic, and industrial applications.
| Standard | Designation | Country / Organization | Description |
|---|---|---|---|
| ASTM | C90500 / B505 / B584 | United States | Standard specification for copper alloy continuous and sand castings (Admiralty Bronze / Gunmetal) |
| BS (British Standard) | BS 1400 LG2 | United Kingdom | Leaded Gunmetal grade for general engineering and marine use |
| EN (European) | EN 1982 CC491K | Europe | Copper-tin-zinc-lead alloy for pressure-tight and wear-resistant castings |
| DIN | DIN 1705 / CuSn5Zn5Pb5-C | Germany | Gunmetal alloy equivalent used for fittings, bearings, and pump parts |
| ISO | CuSn5Zn5Pb5-C | International | Unified composition and mechanical requirements for gunmetal castings |
| IS | IS 318 Gr. 1 / Gr. 2 | India | Leaded tin bronze (Gunmetal) for engineering and marine castings |
| NF (French) | NFA 51-102 CuSn5Zn5Pb5 | France | Admiralty Gunmetal alloy for pressure-tight castings |
| UNS | C90500 | Unified Numbering System | Standard UNS designation for Admiralty Bronze / Gunmetal |
Note: All listed equivalents may vary slightly in tin, lead, or zinc content depending on foundry process and national standards.
Common Names & International Identifiers
Gunmetal, also known as Admiralty Bronze or Leaded Tin Bronze, is a time-proven copper alloy recognized across global engineering and marine industries for its strength, wear resistance, and ability to withstand pressure and seawater corrosion. Below are its widely recognized designations and trade names across international standards.
| System / Standard | Designation | Common / Trade Name | Description / Notes |
|---|---|---|---|
| UNS | C90500 | Admiralty Bronze, Gunmetal | Standard UNS designation for cast copper-tin-zinc-lead alloy |
| BS | LG2 | Leaded Gunmetal | British standard grade for marine and general engineering castings |
| EN | CC491K | CuSn5Zn5Pb5-C | European designation under EN 1982 for pressure-tight castings |
| DIN | CuSn5Zn5Pb5-C | RG5 / G-CuSn5Zn5Pb5 | German equivalent of LG2 gunmetal |
| ISO | CuSn5Zn5Pb5-C | Gunmetal | Internationally harmonized copper alloy designation |
| IS | IS 318 Gr. 1 / Gr. 2 | Gunmetal (Indian Standard) | Leaded tin bronze alloy for marine and general engineering castings |
| NF | NFA 51-102 CuSn5Zn5Pb5 | Admiralty Gunmetal | French equivalent used in hydraulic and pressure applications |
| JIS | BC6 / CAC406 | Gunmetal Bronze | Japanese equivalent grade with similar composition and properties |
Synonyms: Admiralty Bronze, LG2 Bronze, Leaded Gunmetal, Gun Metal Bronze, CuSn5Zn5Pb5-C, RG5 Bronze.
Common Product Forms & Dimensions
C90500 Tin Bronze (also known as SAE 62 or Gunmetal) is supplied by Navkar Metal Syndicate in a range of standard and customized semi-finished forms, manufactured using continuous casting, centrifugal casting, and sand casting techniques. These methods ensure excellent pressure tightness, uniform composition, and fine grain structure — ideal for machining, bearing, and marine service.
Available Forms
- Solid Bars (Rounds)
- Cored Bars / Tubes (Hollow Stock)
- Rectangular Bars / Flats
- Square and Hexagonal Bars
- Plates and Sheets
- Near-Net and Custom Shapes (e.g., gear blanks, billets, bushings, anodes, and profiles)
Typical Size Charts & Ranges
| Form | Outer Diameter (OD) / Width Range | Standard Lengths | Notes |
|---|---|---|---|
| Solid Bars | 1/2" to 10" OD (≈ 12.7 mm to 254 mm) | Typically 144" (12 feet / 3.66 m); custom cut lengths available | Supplied as-cast, rough turned, or machined to size |
| Cored Bars / Tubes | 1" to 16" OD (≈ 25.4 mm to 406.4 mm) | Typically 144" (12 feet); shorter custom lengths available | Ideal for bearings, bushings, and pressure-tight parts |
| Rectangles / Flats | Up to 20" width (≈ 508 mm) | Typically 144" standard; cut-to-size available | Commonly used for wear plates, thrust pads, and seals |
Note on Cored Bar Sizes
Cored bars are produced in various standard combinations of inner diameter (ID) and outer diameter (OD) to reduce machining and material waste. Typical size examples include 0.75" ID × 1.25" OD up to 9.5" ID × 12.0" OD, with intermediate sizes available on request.
Customization
Navkar Metal Syndicate provides cut-to-size and custom profile services for Gunmetal (C90500 / LG2), supporting both one-off and bulk industrial orders. Non-standard dimensions, rough-machined shapes, and pre-finished blanks can be supplied to exact client specifications with full Mill Test Certificates (MTCs) and traceable heat numbers.
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