Classification of Aluminum and Aluminum Alloy Materials (II)

Detailed Introduction to the Eight Series of Aluminum Alloys: Classified by Alloy Composition and Applications

Aluminum, as a lightweight metal material widely used in modern industry, has its model classification closely based on differences in alloy composition and the needs of practical application scenarios. Currently, in the internationally accepted aluminum material model system, it is mainly divided into eight series according to the types and contents of alloying elements, as well as performance characteristics. Each series, due to its unique composition design, exhibits distinct mechanical properties, corrosion resistance, processability, and other traits, thus playing a focused role in numerous fields such as aerospace, architectural decoration, automotive manufacturing, and marine engineering. The following are the detailed characteristics and application directions of the eight series of aluminum materials: 

1. 1××× Series

    Among all series, the 1××× series has the highest aluminum content, with a purity of over 99.00%. The minimum aluminum content of aluminum sheets in this series can be determined by the last two Arabic numerals of the model. For example, the last two digits of the 1050 series are “50”, meaning its aluminum content must reach over 99.5% to meet the qualification standard. 

    This type of aluminum alloy is renowned for its excellent electrical and thermal conductivity and superior corrosion resistance. Although its strength is relatively low, the advantage of low density makes it widely used in fields requiring lightweight materials (such as electronic heat dissipation components, food packaging, and conductive busbars). 

2. 2××× Series 

    A notable feature of 2××× series aluminum sheets is their high hardness. Their main alloying element is copper, with a content ranging from 3% to 5%. This series of aluminum bars are typical aerospace aluminum materials. Compared with the 1××× series, their corrosion resistance is slightly insufficient, so they are less used in general industrial fields and mainly applied to aerospace structural parts with strict strength requirements (such as aircraft skins and frames). 

3. 3××× Series

    The main alloying element of the 3××× series is manganese, with a content of approximately 1.0% to 1.5%. Aluminum materials in this series not only have good corrosion resistance but also exhibit excellent processing performance (such as stamping and bending). Therefore, they are widely used in architectural decoration (such as curtain walls and door/window frames) and the manufacturing of chemical equipment (such as pipelines and storage tanks). 

4. 4××× Series

    The main alloying element of the 4××× series is silicon, with a content of about 4.5% to 6.0%. Its core advantages are low melting point and good corrosion resistance. Meanwhile, aluminum materials in this series have excellent strength and good weldability, making them very suitable for the manufacturing of welded structures. In addition, with a density of approximately 2.7 grams per cubic centimeter, moderate strength, and good heat resistance, they perform outstandingly in the field of high-temperature component manufacturing (such as engine blocks and radiators). 

5. 5××× Series 

    The main alloying element of the 5××× series is magnesium, with a content of about 3% to 5%, so it is also called Al-Mg alloy. It is mainly characterized by low density, high tensile strength, elongation, and fatigue strength, but cannot be strengthened through heat treatment. Aluminum materials in this series are widely used in general industry, especially due to their good seawater corrosion resistance and weldability, making them an ideal choice for shipbuilding, vehicle structures (such as oil tankers and containers), and other fields. 

6. 6××× Series

    The main alloying elements of the 6××× series are silicon and magnesium, with the sum of their contents being approximately 0.8% to 1.5%. Aluminum materials in this series are suitable for components requiring high corrosion resistance and oxidation resistance. They are easy to coat and have excellent processing performance (such as cutting and forging), so they are widely used in the manufacturing of various structural materials, including construction scaffolding, automotive body parts, and rail transit accessories. 

7. 7××× Series 

    The main alloying element of the 7××× series is zinc, with a content of up to 5% to 7%. It belongs to the Al-Mg-Zn-Cu alloy system and can be strengthened through heat treatment, being a typical super-hard aluminum alloy. This series of aluminum materials have good wear resistance but poor corrosion resistance. They are also aerospace aluminum materials and, due to their ultra-high strength (tensile strength up to 500-600MPa), are widely used in key aerospace components (such as airframe frames and landing gears). 

8. 8××× Series 

    The alloy composition of the 8××× series is relatively special, often containing other elements such as lithium and iron (for example, some models contain lithium). Therefore, they have low density and good processing performance. Aluminum materials in this series are suitable for special purposes, such as aluminum foil manufacturing (food packaging, battery aluminum foil) and components used in high-temperature environments (such as internal combustion engine parts). They play an important role in multiple fields such as aerospace, automotive manufacturing, and precision machinery. With the development of material technology, their research, development, and application will continue to promote the progress of aluminum alloy technology.