For centuries, copper, brass, and bronze have played a significant role in human history. It’s worth noting that all three materials are highly recyclable, reducing the need for mining and extraction and contributing to environmental sustainability. These metals are often grouped as “red metals” due to their shared reddish hues, which can lead to confusion, especially when distinguishing between bronze and copper.
So, we have created this article to provide clarity on these differences. We aim to help you understand the distinctions between these metals straightforwardly and clearly. By exploring their unique properties, applications, and comparative advantages, you’ll be better equipped to make informed project decisions. So, let’s begin our exploration of these timeless and valuable metals.
What is Brass?
Brass is a non-ferrous alloy that significantly constitutes copper and zinc. Other elements like aluminum, iron, silicon, manganese, lead, tin, etc., also exhibit various properties in small proportions. However, the higher concentration of zinc makes this alloy solid and ductile.
What is Copper?
Unlike brass and bronze, copper is a pure, non-ferrous transition metal. You can use it directly for processing in industries. However, its alloys can be formed by mixing it with other refined metals. Among various excellent properties of copper, the greatest one is its ability to fight bacteria.
What is Bronze?
Bronze is a dull-gold-colored alloy composed of an excessive amount of copper (88%) and tin (12). That’s why it’s also known as a copper-based alloy. Bronze metal is primarily used in construction, industrial applications, medals, and musical instruments.
Brass vs. Bronze vs. Copper: In-depth Comparison
Brass is a non-ferrous alloy chiefly composed of copper and zinc. There may be involvement of lead, iron, silicon, aluminum, manganese, or some other elements. At the same time, bronze is an alloy of copper due to varying amounts of copper and tin. Nickel, phosphorus, aluminum, and zinc may also be part of bronze alloy.
However, copper is a naturally occurring metal, unlike brass and bronze, often present in its pure form, almost 99.9%.
Another distinction between brass, bronze, and copper is their colors. Typically, the color of the brass metal is yellowish-gold, making it suitable for fittings. At the same time, bronze shows an almost reddish-brown color. However, the color of copper is very similar to bronze. The only difference comes in the shade, as the tone of copper is distinctive and relatively fresh. In comparison, the shade of bronze is comparatively dull.
Comparison based on Properties
Regarding stiffness, bronze exhibits superior characteristics among these three metals. Bronze, due to its composition of copper and tin, is known for its remarkable stiffness and resistance to deformation under mechanical stress. Copper, while a malleable and ductile material, is not as stiff as bronze, making it less suitable for applications that require high stiffness. Brass, with its zinc alloy component, falls between copper and bronze in terms of stiffness.
To differentiate the hardness of three metals, the score of the Brinell hardness scale will work best. So, according to this scale, copper hardness scores 35, brass scores about 55 to 73, and bronze scores 40 to 420. The values determine that bronze is the hardest metal of all. Hence, it’s more susceptible to fractures or cracks.
In terms of toughness, Copper, being a highly ductile and malleable metal, has good toughness. It can deform significantly before fracturing. This is advantageous in applications like electrical wiring, where flexibility and elasticity are more important than hardness.
Brass, while it is less malleable than copper due to the inclusion of zinc, still offers reasonable toughness. It can withstand some degree of deformation before breaking, making it suitable for applications where a balance between toughness and other properties like corrosion resistance is required.
Bronze, because of its alloy composition of copper and tin, often possesses a high level of toughness. It can absorb significant energy before fracturing, making it a preferred choice in applications where strength and toughness are vital, such as in constructing bearings, sculptures, and marine equipment.
Strength or Torsional Strength
Strength is another key property where copper, brass, and bronze differentiate. Copper, though prized for its electrical conductivity, as we have told you, is the least strong among the three. Brass, thanks to its zinc alloy component, exhibits higher tensile strength compared to pure copper. However, its bronze, with its copper and tin composition, stands out as the strongest of the trio.
This makes bronze the preferred choice in applications requiring robust strength, while brass balances strength and other desirable properties. Copper, while less intense, still serves in applications where electrical conductivity and flexibility take precedence over raw strength.
Bending strength refers to a material’s capacity to withstand forces that attempt to deform it by bending. Among brass, copper, and bronze, bronze typically exhibits the highest bending strength. The addition of tin to the copper-tin alloy in bronze enhances its ability to resist deformation when subjected to bending forces.
When comparing brass, copper, and bronze for fatigue strength, bronze often demonstrates the highest fatigue strength. This increased fatigue strength can be attributed to the alloying of copper and tin in bronze. Copper, due to its inherent ductility and malleability, generally exhibits lower fatigue strength.
Compressive strength refers to a material’s ability to resist forces that tend to squeeze or crush it. Again, here, bronze often stands out as the material with the highest compressive strength among the three. Copper, while moderately strong in compression, typically has lower compressive strength than bronze.
Creep resistance is a material’s ability to withstand deformation under constant load or stress, especially at elevated temperatures. Bronze offers good resistance to creep. Copper and brass are less creep-resistant in comparison, which means they are more prone to gradual deformation when subjected to prolonged stress at elevated temperatures.
Tensile Strength and Yield Strength
Tensile strength is necessary when a material goes through the maximum load without being fractured. For this purpose, bronze can bear maximum load without support, making it perfect for processes where material strength is conducted. It can hold a tensile strength between 350 to 635 MPa.
Moreover, brass metal can bear a tensile strength of 338 to 469 MPa. However, copper has the lowest strength among them, at 210 MPa. The maximum point at which material deformation occurs is yield strength. Therefore, bronze has a maximum yield strength of 125 and 800 MPa, higher than copper and brass. On the other hand, copper has the lowest yield, about 33.3 MPa, while brass can withstand 95 to 124 MPa.
Copper, being a pure elemental metal, has a relatively high density. Its density is around 8.92 grams per cubic centimeter (g/cm³). This makes copper a relatively heavy material, which is essential to consider in applications where weight is a concern. Brass density falls between that of copper and zinc. Depending on the specific brass composition, its density typically ranges from 8.4 to 8.73 g/cm³. This places brass in an intermediate range in terms of density. Bronze also falls within a similar density range to brass, typically between 8.5 and 8.8 g/cm³. It shares a similar density profile with brass.
The melting point of metals determines their formability. The materials having low melting points are comparatively easy to form. Among brass vs bronze vs. copper, bronze has the lowest melting point, making it the most formable material.
- Copper melting point: 1085 C
- Brass melting point: 927 C
- Bronze melting point: 913 C
The ability of the material to conduct heat is known as thermal conductivity. Bronze has the highest thermal conductivity between 229 and 1440 BTU/hr-ft²-°F. Whereas copper has a thermal conductivity of 223 BTU/hr-ft²-°F. In contrast, the thermal conductivity of brass is 64 BTU/hr-ft²-°F.
Copper is well-known among the three materials when it comes to electrical usage of material in industries. Copper has almost 100% electrical conductivity, making it the most reliable option for electrical wiring. However, brass is only 28% conductive as compared to copper. Bronze has about 15% electric conductivity, the least electrical conductivity.
Thermal Expansion is one of the other most essential properties where copper is known for its relatively high coefficient of thermal expansion. When heated, copper expands significantly. Brass, an alloy of copper and zinc, inherits some of the thermal expansion characteristics of copper.
However, adding zinc slightly reduces the coefficient of thermal expansion compared to pure copper. Bronze falls in a similar range to brass in terms of thermal expansion. Its coefficient of thermal expansion is also somewhat lower than that of pure copper.
Whenever the metals are compared, corrosion resistance is the most critical parameter. Typically, bronze is the most corrosion-resistant metal than brass and copper. This is because it oxidizes when exposed to air and forms a defensive layer to withstand harsh environments, mainly marine water.
Like bronze, copper also forms a shielding layer upon oxidation, offering excellent corrosion resistance. Yet, if the copper content in both these alloys (bronze and copper) is exposed to chlorine compounds, they may undergo degradation. On the contrary, brass is the least corrosion-resistant alloy. The brass grades that constitute a good quantity of manganese are more corrosion-resistant than others.
Oxidation resistance is the property that can lead to significant differences between copper, brass, and bronze. Copper is susceptible to oxidation when exposed to air and moisture. This results in the formation of a greenish patina over time, which, while offering some protection, does not make it highly oxidation-resistant.
If we talk about brass corrosion, on the other hand, incorporates zinc into its composition, which enhances its resistance to corrosion and tarnishing. Brass is more oxidation-resistant than copper. Bronze tends to excel in oxidation resistance, outperforming both copper and brass. The presence of tin in bronze provides robust protection against oxidation and corrosion, which makes it a preferred material for applications exposed to harsh environmental conditions.
Certainly, in terms of chemical stability, all three materials demonstrate commendable resistance to chemical reactions and corrosion under normal environmental conditions. Copper exhibits high chemical stability, while brass and bronze, as copper alloys with zinc and tin, respectively, inherit good chemical stability.
Regarding thermal stability, bronze is the most heat-resistant material among copper and brass. While copper and brass remain thermally stable at normal temperatures, they have lower melting points than bronze, which can endure higher temperatures without significant deformation or softening.
Casting performance, seen as a crucial property, varies among these three alloys. Copper, known for its high thermal conductivity, allows for detailed and fine castings, making it a choice for artistic and decorative applications. Brass offers a balance between malleability and durability. On the other hand, bronze, with its copper-tin composition, excels in casting intricate and precise components.
Forging is known as the ability of a metal to withstand shaping and forming through heat and pressure. Copper possesses good forging performance. It can be easily forged into a variety of shapes without significant cracking or deformation, making it suitable for applications that require extensive shaping.
Brass also offers decent forging capabilities, combining the malleability of copper with the added strength of zinc. But bronze forging performance is excellent among them. The presence of tin enhances its ability to withstand the forging process, resulting in precise shaping and intricate detailing.
Copper is generally not heat-treatable in the traditional sense. It doesn’t respond well to heat treatment processes, and its properties remain unchanged when exposed to heat, whereas brass is also not typically heat-treatable.
While the individual components, copper and zinc, can be heat-treated separately, the resulting brass alloy does not show significant changes in its properties through heat treatment. Bronze, on the other hand, exhibits some level of heat treatability, especially when additional alloying elements or specific bronze compositions are involved.
Due to the high flexibility of copper, it has excellent formability that cannot be damaged through plastic deformation. So, many micron-sized wires can be made more easily with copper. In addition, brass also features good formability. Yet, bronze metal has extremely low formability due to its hardness.
The ability to join different materials together is termed weldability. The copper, which is oxygen-free, can be readily welded. Therefore, it has high weldability as compared to brass. The copper can be welded using TIG or MIG welding techniques.
However, TIG, MIG, and silver soldering can be used to weld brass alloys. If brass alloy contains less than 20% zinc, it has high weldability. On the other hand, if it contains more than 20% zinc, it has low weldability.
Among other bronze alloys, Silicon bronze is probably the easiest of the bronzes to weld as it has about 3% silicon and 1% manganese. Otherwise, it’s challenging to weld bronze due to its hardness.
In machining, you need a metal that can withstand stress and has more flexibility. According to this, copper is more bendable than brass and bronze. It can withstand machining processes due to its flexibility and high elasticity.
In comparison, brass is less flexible, which makes the machining process more difficult. Moreover, bronze metal is the hardest among them; thus, it has less machinability.
Brass vs Bronze vs. Copper: Applications
Without discussing the significant applications of each metal, their comparison would be incomplete. So, let’s look at some:
|Brass||Decorative and Aesthetic applications||Clocks and watch parts|
|Piping and plumbing equipment|
|Bronze||Versatile metal used for functional and aesthetic purposes||Sculpture|
|Marine applications (boats and ships)|
|Bushings and bearings|
|Petrochemical parts and oil rig equipment|
|Springs and electrical connectors|
|Copper||Machining Applications||Anti-biofuel parts of submarines|
|Heat exchangers and heat sink due to excellent thermal conductivity|
Brass vs Bronze vs Copper: Classification and Available Grades
Brass, bronze, and copper are classified into the following grades:
|Brass||Alloy 260||Also termed a cartridge, has a shiny yellow appearance. It is famous for its excellent cold working properties.||Ammunition, automobiles, fasteners, musical instruments, plugs, electronics, and hardware.|
|Alloy 272||Also known as yellow brass, comprises 62 to 65% copper and 37% zinc. This alloy’s increased amount of zinc makes it sensitive to stress and cracking. Yet, the involvement of tin can reduce the risk||architectural and industrial applications like cold-headed components, pump cylinder liners, and heat exchanger shells.|
|Alloy 330||Or C33000 brass is considered ideal for machining, forming, cold working, soldering, and brazing due to its lower proportion of lead||Commercial, consumer tubing, hardware, and plumbing accessories|
|Alloy 353||Or engraver’s brass, offers high machinability, wear resistance, and strength. Brass 353 comprises 62% copper, 36.2% zinc, and 1.8% lead.||Clocks, gears, hinges, wheels, adapters, couplings, etc.|
|Alloy 360||Referred to as free-machining or free-cutting brass, typically consists of 61.5% copper and 35.5% zinc, enhancing its formability. It features a smooth and gold-like appearance.||Decorative applications and manufacturing of functional parts including bolts, nuts, connectors, pump shafts, and valve stems.|
|Alloy 464||Also known as naval brass, is famous for outstanding corrosion resistance in marine water and caustic environments. Plus, it can withstand high temperatures, making it well-suited for hot forming and bending.||Marine hardware, fasteners, wear plates, condenser tubes, cannons, bushings, etc.|
|Copper||Alloy 101||The most used copper alloy in engineering. High conductivity and ductility are the dominant properties of this oxygen-free copper alloy.||electronic, automotive, and daily-use products|
|Alloy 110||Exhibits exceptional electrical conductivity. The composition of copper is 99.9%, with almost 0.04%, which ensures the purity of this alloy. Though alloy 110 is corrosion-resistant, it’s sensitive to specific chemicals.||Electronics, wiring, plumbing hardware, decorative hardware, etc|
|Alloy 122||Also known as DHP copper, consists of phosphorus, which makes it ideal for heavy-forming applications. Moreover, it’s easy to machine, weld, braze, and form this alloy.||Household and industrial applications such as air conditioners, gas lines, oil burner tubes, refrigerators, and plumbing tubes.|
|Alloy 145||Also known as tellurium copper. It’s named so due to the involvement of significant amounts of tellurium and phosphorus. The key characteristics of this alloy include excellent thermal and electrical conductivity, good machinability, and high formability.||Electrical switches, connectors, clamps, EDM anodes, fasteners, pins, motor parts, and contacts.|
|Bronze||Alloy 932||Has a high level of leaded tin, making it perfect for producing non-pressure parts. It is popular for its exceptional anti-friction and strength quality.||Bearings, valve parts, thrust washers, bushings, light duty gears, and pumps.|
|Alloy 954||An aluminum bronze featuring high yield strength, tensile strength, and excellent ductility. You can use it in different environments without any fear.||Industrial equipment and mounting i.e., bushings and bearings.|
Key Considerations to Choose a Suitable Metal Alloy
After being clear about the differences between copper, brass, and bronze, the next crucial step is to select one. Choosing the right material ensures high-quality results in the formation of parts. The following considerations might be beneficial to make an ideal decision.
- Budget is the foremost factor in choosing a material for your project. The most expensive of the three is copper, while brass is the cheapest. Thus, brass is a suitable option if you’re short of money.
- You must seek the machinability of the material before buying it. Copper is the most machinable metal, so you may go for it to enjoy smooth working.
- Finally, consider the application for which you need the material. For instance, if electrical conductivity is your demand, copper can be the best option, while bronze is ideal for marine water applications.
Once you know every aspect and characteristic of all three metals, i.e., brass, bronze, and copper, distinguishing and choosing between them becomes pretty easy. On the whole, copper has the most favorable properties. But your choice should depend upon your use or application. You must seek help from the critical considerations given above to select an ideal metal for your project.
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