Bronze is a material with broad applications. Bronze metal is sought for its high corrosion resistance in engineering applications and its color and aesthetic value in decorations and medals.
Bronze is used in engine parts, plumbing applications, valves, and fittings. But to understand why bronze is used in so many applications, you must dive deep into bronze alloys and their properties.
In this guide, you’ll learn about different types of bronze, their unique properties, and their applications.
What Is Bronze?
A metal alloy is a mixture of a few metals and non-metals. Bronze is an alloy of copper and tin. Historically, bronze has always been composed of 88% copper and 12% tin.
Many bronze alloys with copper and tin as their primary components are alloyed with other metals like zinc, lead, and phosphorus. The percentage composition of these metals in bronze produces different bronze alloys to match application needs and alter properties like wear resistance and hardness.
Bronze has a metallic, smooth, and reflective finish with a dull golden undertone yellow color and a mix of red tones. It’s mostly regarded as a reddish-brown metal coming from copper.
Bronze is malleable and ductile; it can quickly be hammered, rolled, turned, and cast into many shapes and forms. You can also draw bronze and use extrusion methods without significant resistance.
Bronze naturally forms an outer oxide layer to protect the underlying metal. This natural oxide is called Patina, an oxide of copper and tin. It has a green appearance and protects bronze from corrosion.
Copper
Tin
Zinc
Lead
Statuary Bronze
97 %
2 %
1 %
Architectural Bronze
57 %
40 %
3 %
Commercial Bronze
90 %
10 %
Table of copper composition from the US; GSA
What Are Bronze Alloys?
Bronze itself is an alloy of copper and tin; however, in manufacturing, ‘bronze alloys’ refer to alloys distinctly made from bronze.
Bronze alloys are also copper alloys, and compared to copper, almost all alloys are harder and less malleable than pure copper. Bronze alloys have better wear and corrosion resistance and lower thermal and electrical conductivity than pure copper like C11000 (99.9% Cu).
Bronze alloys are generalized into three types according to their purpose and function. You can find the metallurgical classification of bronze here.
Statuary Bronze
Statuary bronze includes a set of bronze alloys that can be used for sculptures and decorative casting. You can find statuary bronze in displays in the park and in artistic uses. You can identify statuary bronze with its greenish patina over time.
Architectural Bronze
Architectural bronze has a high percentage of zinc (40%). For prestige and quality, architectural bronze is used in door handles, railings, and high architectural applications. Architectural bronze differs from other bronze types because the patina formation is less, and the golden color lasts longer.
Commercial Bronze
Commercial bronze is 90% Copper (Cu), and 10% Zinc (Zn) is brass because it has no tin but is referred to as low brass or red brass. Commercial bronze is highly machinable and is used in hardware and components like screws.
Different Types of Bronze Alloys
In manufacturing, bronze alloys are generally classified according to their alloying metals and composition.
Aluminum Bronze
Aluminum bronze is an alloy with 5-11% aluminium and some other alloying elements. Common aluminum bronze alloys include:
C95200
C95400
C95500
Element
Copper
Aluminum
Silicon
Iron
Manganese
Zinc
% weight
89.0764
10.8230
0.0495
0.0242
0.0242
0.0019
Table of aluminum bronze composition alloy; Source: research gate
Properties of Aluminum Bronze
Strength: The tensile strength of aluminum bronze ranges from 550 – 800 MPa and compares to the strength of steel.
Hardness: The rated Brinell Hardness of aluminum bronze is between 150 – 200.
Corrosion Resistance: It has good corrosion resistance against salt water, chemicals, and low pH liquids and acids. Aluminum forms an oxide layer of alumina that protects the underlying copper from corrosion.
Wear resistance: It has good abrasion resistance and metal wear.
Malleability: It is less ductile than pure copper and harder than copper.
Nickel Aluminum Bronze
Nickel aluminum bronze is a special bronze alloy with nickel and aluminum metal composition. The base alloying elements are 80 % copper, 9 – 11 % copper, 4 – 5 % nickel and iron.
C95800
C95XXX
Element
Copper
Aluminum
Nickel
Iron
Manganese
% weight
79.0
8.5-9.5
4.0-5.0
3.5-4.5
0.8-1.5
Table of aluminum nickel bronze alloy; Source: research gate
Properties of Nickel Aluminum Bronze
Nickel aluminum bronze is a special bronze alloy with nickel and aluminum metal composition. The base alloying elements are 80 % copper, 9 – 11 % copper, 4 – 5 % nickel and iron.
C95800
C95XXX
Tin Bronze
Tin bronze is the oldest type of bronze alloy. It has around 5 – 20 % tin in its composition.
C90500
C91100
Properties of Tin Bronze
Strength: It has a tensile strength that ranges from 350 – 600 MPa for high tin alloys.
Hardness: The rated Brinell Hardness of tin bronze is between 70 -100 for low tin and up to 200 for higher tin content.
Corrosion Resistance: Tin builds the green patina and shields copper from corrosion and decay.
Wear resistance: It has lower wear resistance compared to iron alloyed bronze.
Malleability: Highly machineable and malleable and low tin alloys can be rolled and shaped easily.
Element
Copper
Aluminum
Phosphorus
Lead
Tin
Element
88
0.2
0.6
0.07
11
Table of tin bronze alloy (CC483K); Source: eremetalurji
Phosphor Bronze
Phosphor bronze has a small percentage of phosphorus (less than 0.1%), the remaining being tin and copper.
C51000
C51900
C54400
Purpose of phosphorus: The phosphorus addition in bronze alloys improves the quality of the alloy by forming phosphide particles and acts as a deoxidizer.
Element
Copper
Aluminum
Phosphorus
Lead
Tin
Element
88
1.5 - 4.5
0.01 - 0.05
3.5 - 4.5
3.5 - 4.5
Table of phosphor bronze alloy (C54400); Source: pipingmetal
Properties of Phosphor Bronze
Strength: It has a tensile strength that ranges up to 600 MPa.
Hardness: The rated Brinell Hardness of tin bronze up to 120.
Corrosion Resistance: Performs well in low corrosive environments and ideal for normal moisture in air.
Wear resistance: Lower than bronze alloys with iron and nickel.
Malleability: It is more machineable than pure copper-tin alloys, and it is ductile.
Bearing Bronze
Bearing bronze is a special alloy crafted for bearings and bushings. Bearing bronze handles friction, wear, and tensile and compressive loadings.
C93200
C83600
C90500
Element
Copper
Tin
Silicon
Iron
Zinc
Phosphorous
% weight
81 - 85
6.3 - 7.5
0.01
0.20
2.0 - 4.0
1.5
Table of bearing bronze composition alloy; Source: supplier
Properties of Bearing Bronze
Bearing bronze has a tensile strength of around 250 MPa, C93200 has a tensile strength of 241 MPa.
It has a hardness of 65 HB
A low coefficient of friction
Mild corrosion resistance compared to other grades. It is viable for use in indoor and oiled machines
Manganese Bronze
The major alloying elements of manganese bronze are copper, zinc (40%) and manganese (5%). Manganese provides extra strength and high corrosion resistance for water-based applications, such as machine components that use water coolants.
Manganese changes the structure of the bronze adding strength and making it more corrosion resistant.
C86300
C86500
Element
Copper
Tin
Iron
Manganese
Zinc
Aluminum
Lead
% weight
66
0.20
4.0
5.0
28
7.5
0.20
Table of manganese bronze (C86300) composition alloy; Source: Copper development association
Properties of Manganese Bronze
The mechanical properties of manganese bronze include tensile strength that ranges from 600- 900 MPa, and aluminum bronze typically has the same strength.
It has superior corrosion resistance in sea water, because the manganese prevents the zinc from releasing or breaking away from the alloy
It is not as tough as aluminum nickel bronze
High resistance to wear
Silicon Bronze
Silicon bronze has copper as its primary alloying element and silicon up to 4% with some other elements.
Element
Copper
Silicon
Iron
Manganese
Lead
% weight
Balance
2.0
0.80
0.7
0.05
Table of manganese bronze (C5100) composition alloy; Source: Concast
Properties of Silicon Bronze
Silicon bronze has tensile strength similar to cast iron (gray) and has the advantage of increasing strength with cold working.
It has a Rockwell hardness of around 95 RHB
It has good corrosion resistance
Silicon adds a layer of toughness, making it more tough and abrasion-proof
It has good fatigue resistance and can sustain cycles in the range of 107 at half its tensile strength.
Other properties of silicon bronze make it ideal for some critical applications. It has a great soldering and brazing rating. It can be readily welded with standard procedures like gas welding and spot welds.
How To Choose The Right Brass Alloy?
Your application and specific requirements define the brass alloy. There is a wide variation in property.
For bronze sculptures, an alloy like phosphor bronze offers good machinability, casting ability, and platina, and it shares a historical bond with bronze-age sculptures and bronze tools.
Modern bronze, like aluminum bronze or copper-nickel bronze alloys, excels in saltwater corrosion resistance and is used in marine applications. Alloys like leaded bronze are excellent at reducing friction and anti-spark abilities.
You can match the mechanical properties with the required applications to help you decide the best bronze alloy.
Applications of Different Types of Bronze Alloys
Bronze Alloy
Applications
Aluminum Bronze
Used in marine applications like boat propellers. In industrial applications like valves and gear components.
Nickel Aluminum Bronze
Used in propellers, bushings and bearings. In industrial applications, it is used in gears and frictional metal parts.
Tin Bronze
Bearings and bushings
Bearing Bronze
Coins, bronze tools, and weapons, in musical instruments like bells and electrical contacts
Manganese Bronze
Ship propellers and ship components and wide marine applications
Silicon Bronze
Conduits, Motor rotors and pole line components
Conclusion
Bronze, primarily an alloy of copper and tin, has good strength, wear resistance, is highly corrosion resistan,t and has a unique green patina copper oxide protecting from weathering elements.
This guide explores bronze beyond its standard applications and provides a detailed manufacturing selection process.
FAQs
What is the difference between brass and bronze?
The difference between brass and bronze is the alloying element. Brass is made using copper and zinc, but bronze is made using copper and tin.
Why is bronze no longer used?
Bronze is no longer used due to the discovery of iron and its higher strength and versatility.
Why is bronze so valuable?
Bronze value is tied to its history as a valuable decorative alloy. The alloying elements copper and tin are more expensive than other metals like steel.
Is bronze a good quality?
Bronze is a good quality metal with sought-after properties, specifically being highly corrosion resistant to saltwater.
Is Brass and Bronze the same thing?
Brass is different from bronze. Brass is made of copper and zinc, but bronze is made from copper and tin
Is bronze metal expensive?
Bronze typically costs around 15$ per kg; the real expense is in melting the different alloys and producing the specific bronze alloy for applications.
Is bronze stronger than metal?
Bronze has a comparable strength to iron; its alloys are stronger than some iron alloys. But it is weaker than steel.