Brass
What is brass?
Brass is a copper and zinc alloy that is widely used in the engineering industry, machine shops, and various technical applications. The exact composition of brass can vary, and other metals such as aluminum, lead, or nickel can be added to modify its properties as needed. Brass is well known for its excellent corrosion resistance, strength, and outstanding machinability, making it a popular material for a wide range of uses.
Properties of Brass
Brass combines many features that are advantageous for machining. It is easy to work with using both cutting and forming methods. Brass resists corrosion well, especially in humid environments and seawater. Additionally, it has excellent electrical and thermal conductivity.
Typical properties of brass include:
- Density: approx. 8.4–8.7 g/cm³
- Tensile strength: 250–600 MPa
- Melting point: 900–940 °C
- Thermal conductivity: approx. 120–230 W/(m·K)
- Corrosion resistance: Good, especially in acidic and neutral environments
The composition of brass affects its mechanical and physical properties. For example, adding lead improves machinability, while adding nickel enhances corrosion resistance and gives the alloy a silvery hue.
Types and Alloys of Brass
Brass alloys can be divided into three main groups:
- Lead-free brass – Contains only copper and zinc, making it suitable for drinking water applications and the food industry.
- Lead-containing brass – Includes small amounts of lead to improve machinability, especially for cutting operations.
- Special brass – In addition to lead, may contain other alloying elements such as iron, aluminum, or nickel, which can increase properties such as wear resistance or resistance to stress corrosion.
Uses of Brass
Brass is a popular material in the engineering industry and building components because it is durable and easy to work with. Brass is used in:
- Locks and door handles, where strength and corrosion resistance are required.
- Water fittings and piping, as brass resists moisture and does not rust easily.
- Coins, since it is durable and can be easily stamped.
- Musical instruments, such as trumpets and trombones, because brass resonates well.
- Zippers and screws, which require mechanical durability and formability.
Brass is also well suited for many industrial applications, such as valves and bearings, where a combination of strength, machinability, and corrosion resistance is required.
Brass Corrosion and Dezincification
Although brass is generally highly resistant to corrosion, it can be susceptible to a specific type of corrosion known as dezincification. This occurs when brass comes into contact with a more galvanically active metal or a strong electrolyte, causing the zinc to leach out and leaving behind a porous, copper-rich metal. The risk of dezincification can be reduced by alloying brass with aluminum or nickel, which enhances its durability in harsh conditions.
Summary
Brass is a versatile and well-suited alloy for machinists, offering excellent machinability, strength, and corrosion resistance. Its versatility makes it a key material in numerous industries, especially machine shops and metalworking. By altering the composition of the alloy, brass can be optimized for different uses, and it is also highly recyclable.
