Choosing Between Brass, Bronze, and Copper
Brass, bronze, and copper often tend to confuse and confound design engineers when selecting these materials due to their many similar characteristics, and you might have difficulty distinguishing them at first glance, despite their slightly different appearance in color.
This article therefore shows in detail the differences between brass, bronze, and copper, outlining their different characteristics and applications. Reading this article will help you select the best metal for your machining project!
Contents
Brass, Bronze, Copper: Key Differences
Usually, people refer to them as “red metals” because of their color, but there are some differences. You can review their key differences in the table below:
Property |
Brass |
Bronze |
Copper |
|---|---|---|---|
| Element Composition | Copper (60-90%) + Zinc (10-40%) | Copper (60-95%) + Tin (5-40%) | Copper (Cu) > 99% |
| Appearance | Golden Yellow | Reddish-Brown | Orange-Red |
| Corrosion Resistance | Medium | Excellent | Good |
| Yield Strength | Up to 124 MPa | Up to 800 MPa | Up to 33.3 MPa |
| Tensile Strength | Up to 469 MPa | Up to 635 MPa | Up to 210 MPa |
| Thermal Conductivity | 110-120 W/(m·K) | 80-120 W/(m·K) | 398-401 W/(m·K) |
| Electrical Conductivity | 28-37% IACS | 15-20% IACS | 100-102% IACS |
| Hardness | 60-150 HB | 90-250 HB | 35 HB |
| Machinability | Excellent | Good | Excellent |
Here’s a detailed breakdown of each point to help you understand the differences:
Composition and Alloying Elements
Copper: Of the three metals, copper is the only naturally occurring metallic element. It is called a natural metal and is represented as Cu on the periodic table.
Bronze: Bronze is an alloy of copper and tin, usually containing a percentage of tin, and may also contain other metallic elements such as aluminum, manganese, zinc, and nickel.
Brass: Brass is an alloy consisting of copper and zinc, usually with a high content of copper, while the proportion of zinc varies depending on the application.
Physical Properties (Strength, Durability Differences)
Strength properties are categorized into tensile strength and yield strength; while durability includes corrosion resistance, fatigue strength, and other comprehensive properties.
For bronze: It has the highest tensile strength (up to 635 MPa) and yield strength (up to 800 MPa) of the three materials. The addition of tin increases its strength, giving it a strong structure that is not easily bent, and providing excellent corrosion resistance. Very durable.
For brass: It has medium tensile strength (up to 469 MPa) and yield strength (up to 124 MPa), but the zinc in brass can precipitate and form grain boundaries, which increases the metal’s brittleness, making brass more prone to cracking. It is also less resistant to corrosion than the other two metals.
For copper: It has the lowest tensile strength (up to 210 MPa) and yield strength (up to 33.3 MPa). However, as a natural metal, copper is highly flexible, wear-resistant, and tear-resistant, making it easier to work with and more durable than brass.
In summary, in terms of strength: bronze > brass > copper. But in terms of durability: bronze > copper > brass.
Corrosion resistance
Another significant difference between brass, bronze, and copper is their corrosion resistance.
Bronze: As bronze is exposed to corrosive external environments (e.g., salt water) for long periods, it forms a protective layer on the surface. Therefore, its excellent corrosion resistance makes it ideal for manufacturing parts for use in marine environments.
Copper: It is well known that when copper is exposed to air or water, it forms copper oxide or copper-aluminum. Copper thus has excellent corrosion resistance.
Brass: Brass has lower corrosion resistance compared to bronze and copper, as its oxide film is less protective.
In summary, between bronze, brass, and copper, bronze has the highest corrosion resistance, followed by copper, and brass has the lowest corrosion resistance.
Electrical and thermal conductivity
Electrical conductivity and thermal conductivity are other important factors. Generally speaking, materials with good electrical conductivity also have excellent conductivity. However, factors such as material purity, alloy composition, and temperature can affect both electrical and thermal conductivity.
Copper: Copper has the best electrical conductivity (100-102% IACS) and thermal conductivity (398-401 W/m·K), so you’ll find that most of the wires in your home are made of copper.
Bronze: Bronze has the worst electrical conductivity (15-20% IACS) and thermal conductivity (80-120 W/m·K).
Brass: Brass has second-best thermal conductivity (110-120 W/m·K) and electrical conductivity (28-37% IACS) after copper.
Although some articles mention that bronze has the highest thermal conductivity, based on actual material properties, bronze’s thermal conductivity is usually lower than that of pure copper and brass. Bronze’s thermal conductivity is influenced by its composition, especially the tin content. Practical data shows that the thermal conductivity of bronze ranges from 80-120 W/(m·K), while pure copper reaches 401 W/(m·K), clearly making copper superior in thermal conductivity. That’s why when you open the back cover of your notebook, you’ll find that the CPU and GPU are cooled by copper tubing, precisely because of copper’s excellent thermal conductivity.
Appearance and color
Brass, bronze and copper can also be distinguished by their appearance and color.
Brass is the easiest to distinguish, it is golden yellow in color and has a smooth and shiny surface.
Bronze is a reddish-brown color, which is deepened by the addition of tin. Bronze will produce a lime green coating on the surface over time.
Copper is orange-red, but with time Copper will react with air moisture will generate an oxidation reaction, generating a dark green copper oxide (copper green), the famous Statue of Liberty is an example of copper showing green color under long-term oxidation.
Machinability
Machinability is related to the hardness, toughness, etc. of the metal.
Copper has very good machinability. It is a soft metal and can be easily milled, drilled, turned, soldered and other machining operations. Due to its ductility and plasticity, copper is well suited for the electrical and electronics industry.
Bronze can be less machinable than copper, but is a bit better machinable compared to other alloys such as (steel). However, due to its excellent hardness, it is not suitable for general machining.
Brass is sometimes considered to be very machinable compared to copper and bronze, he will not be machined as easily as brass overheating, the addition of zinc, increased hardness, but maintains a good machinability, brass in the turning, milling and stamping excellent performance.
Weight (Density), Hardness
Weight (density) and hardness are important machining factors for machinists, especially in certain applications where lightweight parts are required.
weight applications.
The density of copper is 8.96 g/cm³. The higher density of copper and the relatively low hardness of pure copper, Brinell hardness, is approximately 35 HB, which makes copper very ductile and machinable.
The density of brass is usually between 8.4 g/cm³ and 8.7 g/cm³, slightly lower than that of pure copper, and the Brinell hardness is usually between 60 HB and 150 HB.
Bronze has a density of 8.7 g/cm³ to 8.9 g/cm³, which is slightly higher than brass but closer to pure copper. Bronze is generally harder than brass and pure copper, with Brinell hardness ranging from about 90 HB to 250 HB.
The density and hardness of both brass and bronze are affected by the content of their alloys (zinc and tin).
Overview of Copper
Copper is one of the first natural metals to be utilized by mankind. This non-ferrous metal has excellent electrical and thermal conductivity, making it an indispensable material in the electrical industry. In addition, copper has good ductility and corrosion resistance, and is widely used in construction and industry.
Copper grades
According to Sequoia Brass & Copper’s Metal Alloy Comparison Guide, the most common copper grades include:
Alloy 101: Also known as Oxygen-Free Copper, oxygen is completely removed, reducing the effect of oxides on electrical conductivity.
Alloy 110: Known as Electrolytic Copper, this is the most electrically and thermally conductive copper, making it ideal for use in electrical and electronic equipment and cables.
Alloy 122: Similar to Alloy 110, but with better solderability.
Alloy 145: also known as Tellurium Copper (0.4%-0.7%) improves electrical conductivity and workability.
Copper applications
As a widely used natural metal, copper is widely used in the electrical and electronic industry including the manufacture of cables and transmission lines, in the heat dissipation system including the heat dissipation copper tubes for computers, and in the construction industry including piping and façade decoration by virtue of its excellent electrical conductivity, thermal conductivity and corrosion resistance.
Overview of Brass
Brass is an alloy of copper and zinc with good mechanical properties, workability and high corrosion resistance. Depending on the ratio of copper to zinc, brass can be of various types, each with different properties and uses. It is widely used in many fields, such as hardware fittings, mechanical parts, musical instruments and so on.
Brass Grade
According to Sequoia Brass & Copper’s Metal Alloy Comparison Guide, the most common grades of brass include
Alloy 260: About 70 percent copper and 30 percent zinc, also known as ammunition brass, has good cold working properties. It is suitable for ammunition, valves, hardware parts, etc.
Alloy 272: Increased zinc content (about 35%) improves hardness and is widely used in industrial construction.
Alloy 330: A small amount of lead has been added, mainly used in the plumbing industry
Alloy 353: further increased lead content, more suitable for parts requiring precision cutting and high wear resistance, such as watch bearings, gears, seals, etc.
Alloy 360: Also known as Free-Cutting Brass, lead has been added to improve machinability and it is commonly used in the manufacture of hardware components, valves and fasteners.
Alloy 385: Architectural Brass, making it suitable for parts used in construction and building systems.
Alloy 464: Also known as Naval Brass, additional small amounts of tin and lead are added to make it used for even excellent corrosion resistance, suitable for parts such as propellers, bearings, and piping in ships
Applications of brass
Brass is widely used in our machining industry due to its good workability, high strength, corrosion resistance and excellent surface quality:
such as precision machine parts: gears, bearings, pumps, valves and seals
Pipes and fittings: joints, valves, flanges
Musical instruments: wind instruments (e.g. trumpets, trombones, saxophones, etc.) and musical instrument parts (e.g. strings, keyboards and acoustic equipment), etc.
Overview of Bronze
Bronze is an alloy of copper and tin. Bronze is used in many industrial and artistic applications because of its excellent corrosion resistance, strength and wear resistance.
Grades of Bronze
According to Sequoia Brass & Copper’s Metal Alloy Comparison Guide, the most common bronze copper grades include
Alloy 932: Lead is added to copper and tin for enhanced wear resistance in scenarios like bushings and washers that require resistance to abrasion.
Alloy 954: Known as an aluminum alloy (5%-12%), it is especially suited for high loads and high temperatures, like in space or at sea.
Applications of Bronze
Bronze is widely used in various industries:
Artistic sculpture: Bronze can be cast and durability, is a variety of monuments sculpture material of choice. By virtue of the natural oxidized copper green can add a sense of art and history for the product.
Mechanical parts and high-strength components: Bronze is most widely used in the machining industry for mechanical parts such as bearings, gears, sliding parts, pistons, pumps, and more.
Marine applications: such as propellers, ship fittings and offshore platform components.
Why Choose Sundi for Your Metal Machining and Prototyping Needs
If you still don’t know the right choice between brass, bronze and copper, please contact SUNDI, as a professional machining expert for dozens of CNC machining machines, EDM, various grinding machines, our experienced engineers have enough expertise and knowledge to handle your mechanical parts in accordance with quality standards and give you an advantage at competitive prices. Contact us today and let’s start the discussion!
FAQs
Which is less expensive, brass, bronze or copper?
Brass is the least expensive, bronze is next, and natural copper is the most expensive.
Which is harder, brass, bronze or copper?
Bronze is the hardest, brass is next, and natural copper is the softest
Why do many people recommend machining with brass?
Brass is versatile, great for CNC machining, and priced right.
Conclusion
This article discusses in detail the differences between brass, bronze, and copper, three metals that are very similar but differ in thermal conductivity, electrical conductivity, corrosion resistance, workability, and more. Therefore, consider these differences when selecting the right material for your pricing program!
