Bronze and brass are two widely used copper alloys in modern manufacturing. They have a rich history dating back thousands of years. While brass and bronze share some similarities, they differ in many ways. Bronze is a copper alloy known for its durability and excellent corrosion resistance. Brass, on the other hand, is valued for its bright gold appearance. 

Before using bronze or brass for your project, you should properly understand the characteristics of these materials to avoid mistakes. This article will explain the properties of bronze and brass and compare their strengths and weaknesses. 

What is Bronze?

Bronze is an alloy that primarily contains copper and tin. Copper makes up 88-95% of the alloy while tin is present in concentrations of 5-12%. They may also contain additional elements including aluminum, silicon, phosphorus, manganese, and nickel. Bronze alloy comes in reddish brown to golden color depending on the concentration. It is non magnetic which makes it useful in electrical and marine applications. 

Furthermore, bronze is harder and more brittle than pure copper. It has high strength and moderate malleability properties. Additionally, bronze is highly corrosion-resistant and develops a protective greenish-blue patina over time to prevent further oxidation. While protective, this patina formation may be undesirable in certain decorative applications. 

What is Brass?

Brass is a metal alloy composed of zinc and copper, ranging from 5-45% and 55-95% respectively. You may also find extra elements such as lead, aluminum, tin, nickel, iron, and silicon that enhance specific properties. Brass has an attractive appearance and retains its shine for a long time. Based on the zinc content, the color of brass is usually reddish gold to bright yellow. 

Most brass alloys are nonmagnetic. However, some high-iron varieties may exhibit slight magnetism. Furthermore, brass is highly workable and is one of the most machinable metals. However, it is prone to dezincification. In certain environments, zinc can leach out and compromise the structure of brass. 

Key Differences Between Brass and Bronze 

Brass and bronze are copper-containing alloys. However, they differ in composition which leads to unique properties. Let’s discuss the differences between brass and bronze in depth.

• Composition 

This is the origin of the differences between brass and bronze. Bronze mainly consists of copper and tin, with additional elements. The presence of tin makes it harder and suited for heavy-duty applications. On the other hand, brass contains mainly copper and zinc with small amounts of other elements to modify its properties. The percentage of zinc determines the hardness and strength of copper. Low zinc brass is softer and more ductile when compared to high zinc brass. 

• Color and Appearance

The color and appearance of bronze and brass are another significant difference. Bronze has a higher copper content which gives it a reddish brown to dark brown color. When bronze components are used for prolonged periods, they develop a greenish-blue patina as a result of copper oxidation. This is very different for brass color and finish. Brass has a shiny finish with a golden-yellow to reddish-gold appearance. It may turn darker and tarnish over time. 

• Strength and Hardness

You can also differentiate between bronze and brass based on their strength and hardness. Bronze is significantly stronger and harder than brass. This property can be attributed to the presence of tin and other elements that make bronze able to withstand heavy loads. Brass owns its softness and malleability to its zinc content. The higher the percentage of zinc, the softer and more ductile brass is. 

• Corrosion Resistance 

Bronze and brass are very different when it comes to withstanding environmental factors such as moisture and harmful chemicals. Bronze has superior corrosion resistance especially in marine environments because of the presence of tin, silicon, and nickel. Additionally, it develops a protective patina when exposed to air and moisture. The corrosion resistance properties of brass are minimal, depending on the zinc content and exposure environment. When brass is exposed to high chloride levels, zinc is selectively leached which leaves a porous copper structure behind.

• Workability and Machinability

The ability to shape, cut, and drill bronze is different from that of brass. Bronze is hard which makes it more challenging to work with. You may find it difficult to cut bronze using CNC machining. For this reason, you may want to cast bronze into various shapes rather than machine extensively. On the other hand, brass is one of the most machinable metal alloys. It is soft and the high zinc content lowers its melting point. Hence, it will be easy to cast, roll, or draw brass into thin sheets.

• Acoustic Properties

Another major difference between bronze and brass is sound and acoustic properties. This refers to how a material vibrates and transmits sound. When bronze is used for precision instruments like cymbals and bells, it produces a warm sound with rich overtones. However, brass is known for its bright and resonant sound. This metal alloy allows for consistent sound production with good sustain. For this reason, brass is used in musical instruments such as trumpets and saxophones.

• Friction and Wear Resistance

You can also differentiate between bronze and brass based on friction and wear resistance. This will help determine how well these materials can withstand repeated pressure and mechanical stress without significant deterioration. Bronze has excellent wear resistance and maintains its structural integrity under high load and continuous movement. On the other hand, brass has lower friction and is more prone to wear and tear. 

• Costs

Bronze and brass are both precious and pricey metal alloys. However, bronze is generally more expensive than brass. There are many reasons behind this. Tin is more costly than zinc which makes the base material more expensive. Additionally, the extra elements increase the price of specific bronze alloys. Furthermore, bronze alloys are harder to machine and require specialized techniques. This increases labor and tooling costs. 

• Applications 

Because of the many differences between bronze and brass, the application you use these materials varies. Bronze thrives in high-stress applications where durability, corrosion resistance, and wear resistance are important. These include marine hardware, bearings, bushings, and heavy-duty machinery parts. On the other hand, bronze is used in applications where low friction and easy machinability are required. It is found in plumbing, fittings, and architectural elements.

Conclusion

Brass and bronze are two unique copper alloys that serve different purposes because of their distinct properties. Bronze has a high tin content which makes it strong and corrosion resistant. The zinc content of brass increases malleability, machinability, and visual appeal. Choosing between bronze and brass depends on a myriad of factors. These include hardness, durability, cost, and application. Careful evaluation of these factors will help you select the best material for specific needs.