Manganese Bronze: Definition, Composition, Properties, and Applications
Manganese bronze is a type of bronze alloy that contains added manganese, aluminum, zinc, and iron. Known for its strength, wear resistance, and corrosion resistance, manganese bronze is widely used in marine applications, and for high-load, high-wear components.
This article will look at what manganese bronze is, what it’s used for, its history, and the properties that differentiate it from similar alloys.
What Is Manganese Bronze?
Manganese bronze is a type of bronze that contains manganese as well as other alloying elements to improve certain physical properties. Bronze alloys have good corrosion resistance, ductility, strength, and thermal and electrical conductivity. The distinguishing property of manganese bronze is its increased strength due to the combination of alloying metals.
Manganese bronze is typically used in applications that require high strength, good corrosion resistance, and thermal conductivity. This includes gears, fasteners, and bearings in the aerospace, marine, and oil & gas industries.
What Is the History of Manganese Bronze?
The history of manganese bronze is linked with the history of Manganese Bronze Holdings, of England. P. M. Parsons patented manganese bronze in 1876 and founded a company, P. M. Parsons. The company was acquired by Manganese Bronze and Brass Co., as Manganese Bronze Holdings was then known, in 1882, primarily producing manganese bronze and white brass, another copper-based alloy. The metals produced by Manganese Bronze and Brass Co. were mainly used for naval and marine equipment, such as marine engines and ship propellers. Manganese bronze in particular was used extensively to manufacture ship propellers.
What Is the Other Term for Manganese Bronze?
Manganese bronze is sometimes also referred to as high-strength yellow brass, manganese brass, or naval bronze. These terms technically refer to different compositions, but they are frequently used interchangeably.
What Is Manganese Bronze Made Of?
Manganese bronze is primarily a copper-zinc alloy that also contains: manganese, iron, aluminum, lead, and tin. The exact composition can differ between manufacturers. As a guide, the following list shows the composition of Concast C86400, as a specific manganese bronze alloy:
- 56–62% Copper
- 0.5–1.5% Lead
- 0.5–1.5% Tin
- 34–42% Zinc
- 0.4–2% Iron
- 0.5–2.5% Aluminum
- 0.1–1.5% Manganese
How Are Manganese Bronzes Made?
Manganese bronzes are a modification of Muntz metal, which are brass alloys. These manganese bronzes are made by first melting copper, and then adding zinc and the other alloying metals. The molten manganese bronze is then cast into molds to set as ingots.
Can Tin Be Turned Into Bronze?
Tin cannot be turned into bronze, however bronze does contain small amounts of tin. Bronze is a group of alloys that consist primarily of copper along with other alloying metals. Modern bronze usually consists of 12% tin and 88% copper, but the amount of tin within bronze can be as low as 0.5%.
What Are the Characteristics of Manganese Bronze?
Manganese bronze has all the usual properties of bronze: high ductility, good thermal and electrical conductivity, and good corrosion resistance. The combination of alloying metals present in manganese bronze greatly increases its strength compared to other types of bronze. For example, UNS C86300, a specific grade of manganese bronze, has a yield strength of 460 MPa and a tensile strength of 820 MPa.
How Does Manganese Bronze Differ From Other Types of Bronze?
Manganese bronze has excellent wear and corrosion resistance compared to other types of bronze due to the addition of manganese. This makes manganese bronze a suitable choice whenever high fatigue strength and corrosion resistance are required, such as in marine applications.
What Is the Color of Manganese Bronze?
Manganese bronze has a yellowish-brown brass color. The surface of manganese bronze might develop a greenish-black patina of copper-oxide over time as the copper inside the manganese bronze reacts with oxygen.
What Does Manganese Bronze Look Like?
Manganese bronze has a yellowish-brown color that may form a dark green patina over time. When polished, the metal is generally smooth with a fine grain structure and a high gloss. Figure 1 below shows a manganese bronze:
Example of manganese bronze.
Image Credit: https://nfm.co.za/product/cda676-manganese-bronze/
What Are the Properties of Manganese Bronze?
Manganese bronze is a yellowish-brown metal with a fine grain structure. It is a very ductile metal that can be cast or forged. Its defining properties are its strength and wear resistance. Manganese bronze displays excellent strength compared to other bronzes, as well as fatigue strength, leading to excellent resistance to wear.
Manganese bronze displays good resistance to corrosion from seawater, which makes it an excellent choice for marine applications.
What Are the Mechanical Properties of Manganese Bronze?
Table 1 shows some of the mechanical properties of UNS C86300, a specific manganese bronze:
| Physical Property | Description |
|---|---|
Physical Property Hardness (Brinell) | Description 225 |
Physical Property Yield Strength | Description 460 MPa |
Physical Property Tensile Strength | Description 820 MPa |
Physical Property Density | Description 7.70 g/cc |
Physical Property Elastic modulus | Description 117 GPa |
Physical Property Fatigue strength | Description 170 MPa |
Physical Property Machinability | Description 8% |
Is Manganese Bronze Harder Than Silicon Bronze?
Manganese bronze is harder than silicon bronze. Manganese bronze has a Brinell hardness of around 225, while silicon bronze has a hardness of 11.5–14.5. Silicon bronze consists of 94–96% copper and 2.5%–6% silicon, with traces of other elements also present. Manganese bronze consists of 56–62% copper, and 34–42% zinc, as well as other metals such as: manganese, aluminum, iron, and lead. The presence of manganese, aluminum, and zinc all serve to increase the hardness of manganese bronze.
Is Manganese Bronze Strong?
Yes, manganese bronze is known for its strength in comparison to other types of bronze. The presence of manganese increases the yield strength of the bronze to around 460 MPa and the tensile strength to 820 MPa. The primary distinguishing properties of manganese bronze are its tensile strength and wear resistance, which itself is a property of its fatigue strength.
What Are the Chemical Properties of Manganese Bronze?
Table 2 shows some of the chemical properties of UNS C86300, a specific type of manganese bronze:
| Chemical Property | Description |
|---|---|
Chemical Property Thermal conductivity | Description 2.95 W/m-K |
Chemical Property Melting point | Description 885–920 °C |
Chemical Property Corrosion resistance | Description Excellent |
What Is Manganese Bronze Used For?
Manganese bronze is used primarily in applications that require good corrosion resistance, high strength, and good wear resistance and longevity. This combination of properties makes manganese bronze highly suited for marine applications, applications in corrosive environments, and applications in which components are routinely subjected to wear, or require longevity.
What Are the Applications of Manganese Bronze?
Manganese bronze is used in a wide variety of applications, such as:
1. Gears
Manganese bronze is a popular material choice for gears due to its strength, wear resistance, and low friction coefficient. Gears are constantly in contact with each other and can experience great amounts of wear. The strength and wear resistance of manganese bronze make it able to withstand gears operating under heavy loads that require longevity. The corrosion resistance of manganese bronze gives the added benefit of these gears being suitable for marine applications, or other applications in corrosive environments.
2. Bearings
Manganese bronze contains lead, which adds anti-seizing properties, as well as increases lubricity. This ensures the smooth operation of bearings. The wear resistance, strength, and impact resistance of manganese bronze make it suitable for high-speed and high-load-bearing applications.
3. Bushings
Manganese bronze has self-lubricating properties, which reduce friction and wear, and extend the life span of the bushing. This unique property makes it ideal for bushings, which are prone to wear over time. Along with this, the strength and wear resistance of manganese bronze increases the durability and longevity of bushings, making them a popular choice.
Bushings made from manganese bronze are commonly used in: marine applications, pumps, and other machinery.
4. Lead Screw Nuts
Lead screws are linear actuators that convert rotational motion to linear motion. The lead screw nut rotates on the lead screw shaft, causing the shaft of the nut to move linearly while the other is fixed. Lead screws and lead screw nuts may be subjected to high loads, and need to perform reliably over their life span to provide accurate movement.
Manganese bronze is a popular choice for lead screw nuts due to its strength, which can withstand high loads, and its wear resistance, which increases the life span of the nut and ensures reliable movement across its life span.
5. Parts of Landing Gear
Landing gear components require high strength to withstand the forces of a landing aircraft. Manganese bronze is a popular choice for certain landing gear components due to its increased strength, as well as its wear resistance. The corrosion resistance of manganese bronze has the added benefit of protecting the landing gear against corrosion due to atmospheric moisture and rainy weather.
6. Strut Bushings
Strut bushings are specialized bushings used for the strut rods of a car. These bushings absorb the majority of load when braking, and are subject to large amounts of wear, which can affect braking performance over time.
Manganese bronze exhibits the strength and enhanced wear resistance required for strut bushings. The corrosion resistance of manganese bronze is also useful to protect against environmental conditions.
7. Parts of Screw Manufacturing Machines
Screw manufacturing machines are automated machines that produce screws. They contain various components such as: gears, bearings, and bushings which operate at high speeds for long periods. As such, these components are subject to wear over their life span.
Manganese bronze displays strength and wear resistance to reduce the rate of wear, increasing the life span of these components.
What Are the Advantages of Manganese Bronze?
Manganese bronze has the following advantages over other types of bronze:
- The presence of manganese and other alloying metals greatly increases the strength of manganese bronze, compared to other types of bronze.
- Has a high fatigue strength, making it resistant to wear and increasing the longevity of parts.
- Manganese bronze, similar to other bronzes, has good corrosion resistance, making it very suitable for marine applications or other corrosive environments.
What Are the Disadvantages of Manganese Bronze?
Manganese bronze has some disadvantages compared to other types of bronze:
- Due to its high strength, manganese bronze’s machinability suffers. Manganese bronze does not respond well to cutting and machining and may damage machining tools.
- Is a relatively complex bronze to produce, which is reflected in its cost, which can be significantly higher than other types of bronze.
- Vulnerable to abrasive conditions, which can weaken its structural integrity.
Is Manganese Bronze More Expensive Than Steel?
Manganese bronze is generally more expensive than steel. Steel is an iron-carbon alloy and may refer to various types of steel, such as: carbon steel, stainless steel, tool steel, and alloy steel. The term steel generally refers to carbon steels, which are by far the most common type of steel, as well as the cheapest to produce.
In general, copper-based alloys are more expensive than steels, due to the different costs of manufacturing, as well as the base metals that these alloys are made of. Manganese bronze specifically is a type of bronze that is more expensive than others due to its complex production process.
Does Manganese Bronze Rust?
No, manganese bronze does not rust. Rust is iron oxide, which is formed as a reaction between iron and oxygen. This reaction is exacerbated when moisture is present. Manganese bronze contains a small amount of iron but has excellent corrosion resistance properties which protect it from rust.
Like other bronzes, the surface of manganese bronze may produce a copper oxide surface layer when exposed to oxygen, but this layer protects the rest of the material from further oxidation and damage.
Does Manganese Bronze Turn Green?
Yes, manganese bronze may turn green. This is due to the copper content of manganese bronze and is a common occurrence with all types of bronze and brass. The green layer that appears over time is copper oxide, which forms due to a reaction between the oxygen in the air and the copper in the metal. This copper oxide forms a surface layer that protects the underlying metal from further oxidation and degradation.
What Is the Difference Between Manganese Bronze and Titanium?
Manganese bronze and titanium are very different metals with different properties and applications.
Manganese bronze is mainly a copper-zinc alloy with other alloying metals present, while titanium is an elemental metal that is primarily used in alloy form. Manganese bronze is stronger than pure titanium, with a higher strength-to-weight ratio. Titanium is less dense than manganese bronze, with a density of 4.5 g/cc compared to 7.7 g/cc. Manganese bronze is much harder than titanium, with a Brinell hardness of 220 compared to titanium’s hardness of 70.
What Is the Difference Between Manganese Bronze and Manganese Brass?
Manganese bronze is sometimes referred to as a type of brass because the compositions of bronzes and brasses have a high degree of overlap. As such, manganese bronze may sometimes be referred to as manganese brass.
Summary
This article presented manganese bronze, explained it, and discussed its properties and various applications. To learn more about manganese bronze, contact a Xometry representative.
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