Brass and bronze are among the first alloys that were ever produced. The bronze metal alloy, in particular, lends its name to a period of human history that spans more than 1,000 years.
Nevertheless, most people would find explaining the difference between brass and bronze a challenge, partially because the difference between the two is slight. They are both forms of industrial copper and are more accurately described as copper alloys than as distinct metals compared to other metals. Only their extraordinarily long use has defined brass and bronze as distinct metals.
The different additives added to the copper—zinc for brass and tin for bronze—do lend the alloys different properties. Visually the differences between the two can be recognized by color. Brass is typically brighter yellow, and bronze is a redder shade or a darker brown. However, this can vary by their exact mixture, with the properties also being highly variable.
We refer to the bronze age of human history instead of the brass age because bronze is more suitable for use in tools and weapons due to the addition of tin, which gives it greater tensile strength and hardness. On the other hand, adding zinc provided brass corrosion resistance and made it more suitable for decoration. Brass has also found more utilitarian purposes in the modern period, however.
Below we detail the modern uses of the two alloys in the manufacturing process, the differences between brass and bronze, and what makes each unique.
Modern Additives for Brass and Bronze
Industrial applications in the modern world require modern materials, and a variety of other elements have been introduced in the age-old mixtures of brass and bronze-copper alloys. The most common—and perhaps surprising—is silicon. Adding this non-metallic element to the mix lends the alloy the following improvements:
- Like brass, bronze resists corrosion
- Decreased electrical conductivity
- Increased fluidity during casting
- Reduced brittleness
- Reduced contraction of the cooling metal
- Reduction of the final alloy’s oxygen content
The addition of silicon is common in decorative brass and bronze, as these are frequently cast. A variety of metals can be introduced to copper in addition to zinc or tin to change the resulting alloy’s properties further. Bronze is stronger and more structural than brass alloys and is the copper alloy that is most commonly mixed with other metals.
Some of the more common of these elements and the properties they lend to bronze can be viewed in the table below.
|Creates a layer of lead that reduces friction and wear between parts
|Bearings in aerospace engines as well as crankshafts for automotive and other internal combustion engines
|Enhances castability, wear resistance, and stiffness of bronze alloy
|Springs, dental bridges, reeds for musical instruments, electrical contact points, and electrical switches
|Improved corrosion resistance and anti-microbial and anti-biological properties
|Oil industry applications and marine environments where corrosion and colonization by organisms are a concern
|Good corrosion resistance and enhanced strength
|Aerospace and marine fasteners, bearings, bushings, landing gear struts, and others
Frequently, multiple additives are added to create special-purpose bronzes. For example, manganese, aluminum, and lead are often found together in the bronzes that are used in aerospace engine bearings. Additionally, a range of bronzes incorporate different percentages of aluminum and may also include iron and zinc, the latter of which defines an alloy as brass. The confusion between brass vs bronze owes to the fact that the lines are so easily and so frequently blurred.
Understanding the Difference Between Brass and Bronze
Their uses often determine the difference between bronze and brass. Brass, with its brighter luster, is often used for ornamental or decorative purposes than bronze. Also, adding zinc makes for a finer-grained copper alloy that is more easily and precisely machined, making brass the preferred choice for gearings that must make minute micrometers or smaller adjustments. This means that decorative lighting and precision microscope gearings are made of the same alloy.
Bronze has a similar dichotomy. It is known for being the stronger of the two alloys. One of its most frequent uses is in casting monumental statuary that stands in front of major civic buildings and, most famously, the material for Olympic medals that don’t come with sponsorship deals. It is this ornamental use that people are most familiar with. However, bronze copper alloys are spark-resistant, and some of their most common uses are in flammable gas line fittings, bearings in high rotation and high-tech engines, and countless other highly technical applications.
The difference between brass and bronze is academic and mostly owes to the long history of the alloys. The range of copper alloys the terms refer to are still used daily, however, and the unique properties specific to certain blends are highly sought after by engineers and machinists for industrial and high-tech applications where sparking or corrosion must be prevented. This leads to a robust market for brass and bronze alloys for general use and highly specialized technical applications.