Brass vs. Bronze vs. Copper: Key Differences Explored

As previously mentioned, these metals possess many features that set them apart. We will categorize these differences into several sections for clarity.

Available Alloys

Brass Alloys
Brass is versatile and comes in various alloys, including:

• Alloy 260 (Cartridge Brass): Known for excellent cold working characteristics, it’s used in automotive applications, ammunition, and fasteners.
• Alloy 272 (Yellow Brass): Contains about 33% zinc, making it ideal for industrial applications.
• Alloy 330: Offers high machinability and low lead content, suitable for piping applications.
• Alloy 353 (Clock Brass): Perfect for high-precision clock components due to its excellent machinability.
• Alloy 360: The most common brass grade, known for its machinability and suitability for fittings, fasteners, and valves.
• Alloy 464 (Naval Brass): Renowned for its corrosion resistance, it withstands temperature changes and is useful for various applications.
  
  

Bronze Alloys
Bronze also comes in multiple grades, including:

• Alloy 932: High-leaded bronze used for making washers and bushings.
• Alloy 954: An aluminum bronze alloy for industrial and mounting applications.

Copper Alloys
Copper is another option in rapid prototyping with common alloys such as:

• Alloy 101: Oxygen-free copper with high ductility and conductivity.
• Alloy 110: Electrolytic copper with superior thermal and electrical conductivity.
• Alloy 122: Similar to Alloy 110 but with better weldability.
• Alloy 145: Tellurium copper with excellent electrical and thermal conductivity.

Material Properties

Understanding the material properties will aid your selection process. Here’s a breakdown:

• Element Composition:

  • Copper: A pure, naturally occurring non-ferrous metal.
  • Brass: An alloy of copper and zinc, often containing lead and other elements.
  • Bronze: An alloy of copper, primarily with tin but may also include nickel and aluminum.

• Corrosion Resistance:

  • Bronze forms a protective layer (patina) when oxidized, making it corrosion-resistant, especially in marine applications.
  • Copper also forms a protective layer but degrades with continuous exposure to chlorine compounds.
  • Brass has lower corrosion resistance, although some grades with high manganese content are better.

• Durability:

  • Bronze is strong and resistant to bending, while copper is flexible but durable.
  • Brass is more prone to cracking compared to the other two metals.

• Weight:

  • Brass is the lightest at about 8720 kg/m³, followed by bronze (7400 to 8900 kg/m³), with copper being the heaviest at 8930 kg/m³.

• Machinability:

  • Copper offers better machinability due to its flexibility, while brass and bronze are less machinable.

• Weldability:

  • All three metals can be welded, but copper and brass have better weldability compared to bronze.

Conductivity Differences

• Electrical Conductivity: Copper has 100% conductivity, brass around 28%, and bronze about 15%.
• Thermal Conductivity: Bronze leads with 229 to 1440 BTU/hr-ft²-°F, followed by copper at 223 BTU/hr-ft²-°F, and brass at 64 BTU/hr-ft²-°F.

Strength Differences

• Tensile Strength: Bronze is strongest (350 to 635 MPa), followed by brass (338 to 469 MPa), with copper at 210 MPa.
• Yield Strength: Bronze also leads (125 – 800 MPa), brass follows (95 to 124 MPa), and copper has the least (33.3 MPa).

Appearance and Touch

• Color: Brass has a yellowish-gold hue, while bronze is reddish-brown, similar to copper but duller. Freshly exposed copper is distinctive in color.
• Hardness: Copper scores 35 on the Brinell hardness scale, brass ranges from 55 to 73, and bronze scores between 40 and 420, making bronze the hardest.

Pricing

Prices for brass, bronze, and copper vary based on their grades and alloys. Generally, copper is the most expensive, followed by bronze, while brass is the least costly due to its higher zinc content.