Aluminum alloys are an indispensable material in modern society. Because they are light, strong, and easy to process, they are used in various fields such as aircraft, automobiles, and construction.
This article explains the types and characteristics of aluminum alloys and how to select them by application. By comprehensively explaining everything from basic knowledge of aluminum alloys to specific application examples, we aim to help readers gain a deeper understanding of aluminum alloys and make appropriate material selections.
By the time you finish reading this article, you will have deepened your knowledge of aluminum alloys and obtained information that will be useful in material selection. Please read to the end and deepen your understanding of aluminum alloys.
Basic Knowledge of Aluminum Alloys
Definition and Classification of Aluminum Alloys
Aluminum alloys are alloys made mainly of aluminum, with other metal elements added to improve strength, corrosion resistance, etc. Alloys with various properties are made depending on the type and amount of elements added.
Aluminum alloys are broadly classified into two types: casting alloys and wrought alloys.
- Casting Alloys: Alloys that are molded by pouring from a molten state into a mold. Suitable for manufacturing products with complex shapes.
- Wrought Alloys: Alloys that are molded by processing such as rolling, extrusion, and forging. Processed into plates, rods, shaped materials, etc., and used for various applications.
Furthermore, they are classified by numbers from 1000 series to 8000 series depending on the alloy composition and properties.
- 1000 Series: Pure aluminum (99.00% or more)
- 2000 Series: Alloys with Cu as the main additive element
- 3000 Series: Alloys with Mn as the main additive element
- 4000 Series: Alloys with Si as the main additive element
- 5000 Series: Alloys with Mg as the main additive element
- 6000 Series: Alloys with Mg and Si as the main additive elements
- 7000 Series: Alloys with Zn as the main additive element
- 8000 Series: Alloys with other elements as the main additive element
Properties of Aluminum Alloys
Aluminum alloys have the following excellent properties.
- Lightweight: Aluminum has a specific gravity of about 2.7, which is about 1/3 the weight of iron. Therefore, it is ideal for products that require weight reduction.
- High Strength: Alloys with high strength are made by adding elements and heat treatment.
- Corrosion Resistance: Aluminum forms an oxide film on its surface, so it has excellent corrosion resistance.
- Processability: Various processing such as rolling, extrusion, forging, and cutting is possible.
- Thermal Conductivity: High thermal conductivity, suitable for heat exchangers, etc.
- Recyclability: Easy to recycle, low environmental impact material.
Types and Characteristics of Aluminum Alloys
Aluminum alloys are made into alloys with various properties depending on the type and amount of added elements. Here, we will explain in detail the types and characteristics of representative aluminum alloys.
| Series | Main Additive Element | Characteristics | Main Applications | Representative Alloys |
|---|---|---|---|---|
| 1000 Series | Pure Aluminum | High corrosion resistance, processability, conductivity, and thermal conductivity | Electrical parts, heat exchangers, roofing materials, cookware | A1050, A1100 |
| 2000 Series | Copper (Cu) | High strength, high toughness, fatigue resistance, and heat resistance | Aircraft parts, structural materials, sports equipment | A2017, A2024 |
| 3000 Series | Manganese (Mn) | Moderate strength, good corrosion resistance, processability, and weldability | Aluminum cans, building materials, heat exchangers, cookware | A3003, A3004 |
| 4000 Series | Silicon (Si) | Good castability, wear resistance, and low thermal expansion | Pistons, cylinders, welding wires | A4032 |
| 5000 Series | Magnesium (Mg) | High strength, good corrosion resistance and weldability, low-temperature properties | Automobile parts, ship parts, structural materials, tanks | A5052, A5083 |
| 6000 Series | Mg + Si | High strength, good corrosion resistance, extrudability, and heat treatability | Aluminum sashes, building materials, vehicle parts, heat exchangers | A6061, A6063 |
| 7000 Series | Zinc (Zn) | Highest strength, good corrosion resistance and heat treatability | Aircraft parts, sports equipment, precision machine parts | A7075 |
| 8000 Series | Other | Special properties (varies depending on application) | Special applications (wires, packaging materials, etc.) | – |
1000 Series Aluminum Alloys
1000 series aluminum alloys are alloys based on pure aluminum. It is characterized by high purity with an aluminum content of 99.00% or more.
Characteristics
- Corrosion Resistance: Shows excellent corrosion resistance because it forms a dense oxide film on the surface.
- Processability: Soft and excellent in ductility, so processing such as rolling, extrusion, and forging is easy.
- Conductivity: High electrical conductivity, used for electrical parts, etc.
- Thermal Conductivity: High thermal conductivity, used for heat exchangers, etc.
Main Applications
- Electrical parts (conductors, electrodes, etc.)
- Heat exchangers
- Chemical plants
- Roofing materials, exterior wall materials
- Cookware
Representative Alloys
- A1050: High purity, excellent corrosion resistance and processability.
- A1100: An alloy with a small amount of copper added to A1050, with slightly improved strength.
2000 Series Aluminum Alloys
2000 series aluminum alloys are alloys with copper (Cu) as the main additive element.
Characteristics
- High Strength: One of the alloy systems with the highest strength among aluminum alloys.
- High Toughness: High resistance to impact and vibration.
- Fatigue Resistance: High resistance to repeated loads.
- Heat Resistance: Relatively high high-temperature strength, suitable for use in high-temperature environments.
Main Applications
- Aircraft parts (wings, fuselage, etc.)
- Structural materials
- Sports equipment
Representative Alloys
- A2017: An alloy known as duralumin, which balances strength and processability.
- A2024: An alloy known as super duralumin, which has higher strength than A2017.
3000 Series Aluminum Alloys
3000 series aluminum alloys are alloys with manganese (Mn) as the main additive element.
Characteristics
- Moderate Strength: Has moderate strength, higher than 1000 series and lower than 5000 series.
- Good Corrosion Resistance: Shows the same level of corrosion resistance as the 1000 series.
- Good Processability: Processing such as rolling, extrusion, and deep drawing is easy.
- Weldability: Excellent weldability.
Main Applications
- Aluminum cans
- Building materials (sashes, roofing materials, exterior wall materials, etc.)
- Heat exchangers
- Cookware
Representative Alloys
- A3003: An alloy with manganese added to the 1000 series, improving strength and corrosion resistance.
- A3004: An alloy with higher strength than A3003.
4000 Series Aluminum Alloys
4000 series aluminum alloys are alloys with silicon (Si) as the main additive element.
Characteristics
- Good Castability: Good fluidity in the molten state, suitable for manufacturing castings with complex shapes.
- Wear Resistance: High resistance to wear.
- Low Thermal Expansion: Low coefficient of thermal expansion, little dimensional change due to temperature changes.
Main Applications
- Pistons
- Cylinders
- Welding wires
Representative Alloys
- A4032: An alloy used for pistons, etc., with excellent wear resistance and heat resistance.
5000 Series Aluminum Alloys
5000 series aluminum alloys are alloys with magnesium (Mg) as the main additive element.
Characteristics
- High Strength: Higher strength than the 3000 series.
- Good Corrosion Resistance: Especially excellent corrosion resistance to seawater.
- Good Weldability: Excellent weldability.
- Low-Temperature Properties: Maintains strength and toughness even at low temperatures.
Main Applications
- Automobile parts (wheels, bumpers, etc.)
- Ship parts
- Structural materials
- Tanks
Representative Alloys
- A5052: Excellent processability, corrosion resistance, and weldability.
- A5083: Higher strength than A5052, used for ships and tanks, etc.
6000 Series Aluminum Alloys
6000 series aluminum alloys are alloys with magnesium (Mg) and silicon (Si) as the main additive elements.
Characteristics
- High Strength: Has the same level of strength as the 5000 series.
- Good Corrosion Resistance: Shows the same level of corrosion resistance as the 5000 series.
- Good Extrudability: Suitable for manufacturing products with complex shapes by extrusion.
- Heat Treatability: Strength can be adjusted by heat treatment.
Main Applications
- Aluminum sashes
- Building materials (window frames, door frames, etc.)
- Vehicle parts
- Heat exchangers
Representative Alloys
- A6061: An alloy whose strength can be adjusted by heat treatment, with high versatility.
- A6063: Excellent extrudability, used for aluminum sashes, etc.
7000 Series Aluminum Alloys
7000 series aluminum alloys are alloys with zinc (Zn) as the main additive element.
Characteristics
- Highest Strength: The alloy system with the highest strength among aluminum alloys.
- Good Corrosion Resistance: Also excellent corrosion resistance.
- Heat Treatability: Strength can be adjusted by heat treatment.
Main Applications
- Aircraft parts
- Sports equipment (bicycle frames, skis, etc.)
- Precision machine parts
Representative Alloys
- A7075: An alloy known as extra super duralumin, which has the highest strength among aluminum alloys.
8000 Series Aluminum Alloys
8000 series aluminum alloys are alloys with other elements as the main additive elements, which are not classified in any of the above.
Characteristics
- Special Properties: Alloys with special properties such as heat resistance, wear resistance, and corrosion resistance are made depending on the added elements.
Main Applications
- Aircraft parts
- Electronic parts
- Welding wires
Representative Alloys
- A8090: An alloy with lithium added, realizing both lightweight and high strength.
How to Choose Aluminum Alloys by Application
Aluminum alloys are used for various applications depending on their properties. By selecting the appropriate alloy, it is possible to improve product performance, reduce weight, and reduce costs. Here, we will explain how to select the optimal aluminum alloy for each application.
Selection Criteria
When choosing an aluminum alloy, the following factors should be considered:
- Strength: Select the appropriate alloy system according to the required strength. Choose 2000 series or 7000 series for high strength requirements, and 3000 series or 5000 series for moderate strength requirements.
- Corrosion Resistance: Select a highly corrosion-resistant alloy according to the corrosiveness of the usage environment. Especially when exposed to seawater or acid rain, the 5000 series, which has excellent corrosion resistance, is suitable.
- Processability: Select an alloy with good processability according to the required processing method. For processing into complex shapes, the 1000 series or 3000 series, which have excellent ductility, are suitable.
- Cost: Alloy prices vary widely, so cost must also be considered.
- Other: Thermal conductivity, electrical conductivity, weldability, and surface treatability should also be considered.
Application Examples and Recommended Alloys
| Application | Recommended Alloy | Selection Reason |
|---|---|---|
| Aircraft Parts | 2000 Series, 7000 Series | High strength, high toughness, fatigue resistance |
| Automobile Parts | 5000 Series, 6000 Series | High strength, good corrosion resistance, weldability |
| Building Materials | 3000 Series, 6000 Series | Moderate strength, good corrosion resistance, processability |
| Aluminum Cans | 3000 Series | Good corrosion resistance, processability, recyclability |
| Heat Exchangers | 1000 Series, 3000 Series | High thermal conductivity, corrosion resistance |
| Electrical Parts | 1000 Series | High electrical conductivity, corrosion resistance |
| Sports Equipment | 7000 Series | Highest strength, good corrosion resistance |
| Castings | 4000 Series | Good castability |
Future Prospects for Aluminum Alloys
Demand for aluminum alloys is expected to continue to expand in various fields in the future due to their excellent properties such as lightweight, high strength, and corrosion resistance. In particular, demand is increasing for the purpose of reducing the weight of automobiles and improving the fuel efficiency of aircraft.
Trends in Supply and Demand
With the increase in global demand for aluminum, the demand for aluminum alloys is also increasing. According to a report by Fortune Business Insights, the global aluminum market size is projected to reach US$259.8 billion in 2028, up from US$167 billion in 2021 [1].
On the other hand, the supply of bauxite, the raw material for aluminum, is concentrated in major producing countries such as Australia, China, and Guinea, and there are concerns about supply risks.
Development Trends for New Aluminum Alloys
Development of new aluminum alloys with higher strength, higher corrosion resistance, and higher functionality is underway. For example, in the aircraft field, the development of aluminum lithium alloys that combine weight reduction and high strength is underway.
In addition, the evolution of 3D printer technology has made it possible to manufacture aluminum alloy parts with complex shapes, and the development of new applications is expected.
Efforts to Reduce Environmental Impact
Although aluminum alloys are materials with excellent recyclability, energy consumption and CO2 emissions during the manufacturing process are issues. Therefore, efforts are underway to reduce environmental impact, such as improving the efficiency of the manufacturing process, using renewable energy, and improving recycling technology.
Summary
Aluminum alloys are lightweight, high-strength, and have excellent corrosion resistance and processability, and are used in a wide range of fields such as aircraft, automobiles, and construction. This article explained the difference between casting alloys and wrought alloys, and the properties and applications of each alloy from the 1000 series to the 8000 series. Please use it as a reference for appropriate material selection.
