Aluminum sheet: lightweight and multifunctional green metal sheet

In modern industry and consumer sectors, aluminum sheet, with its core competitive advantages of "aluminum's inherent advantages and flat form," has become a lightweight, cost-effective material that cannot be replaced by steel sheet. Made from pure aluminum or aluminum alloys, it is processed into a flat sheet through hot rolling, cold rolling, and surface treatment. While inheriting aluminum's core properties of low density (2.7g/cm³, only one-third that of steel), natural corrosion resistance (surface oxide film), high thermal and electrical conductivity, and ease of processing, its flat form adapts to diverse applications, including decorative, structural, and functional components. It is widely used in architectural decoration, transportation, electronics, and new energy, making it a key foundational material for the "lightweight manufacturing" and "green and low-carbon" trends.

I. Basic Concepts and Core Composition of Aluminum Sheet

The core component of aluminum sheet is aluminum (Al). It is categorized into pure aluminum and aluminum alloys based on application requirements. Its manufacturing process is similar to that of steel sheet, but due to the material properties of aluminum (its melting point is 660°C, far lower than steel's 1538°C), the rolling process emphasizes low-temperature forming and surface oxidation control. (I) Material Basics: Core Differences Between Pure Aluminum and Aluminum Alloys
Pure aluminum sheet: Aluminum purity ≥ 99.0% (e.g., 1050 and 1060 pure aluminum). Higher purity improves electrical and thermal conductivity and corrosion resistance, but also reduces strength (tensile strength approximately 90-120 MPa). It is suitable for applications requiring high electrical conductivity and corrosion resistance but low strength (e.g., conductive sheets and food packaging substrates).
Alloy aluminum sheet: Alloying elements such as magnesium (Mg), silicon (Si), manganese (Mn), and zinc (Zn) are added to pure aluminum to enhance strength through solid solution strengthening while retaining aluminum's lightweight advantages. Different alloying elements contribute to different properties:

Magnesium (Mg): Improves corrosion resistance and toughness (e.g., 5-series aluminum-magnesium alloys, with a tensile strength of 200-300 MPa, suitable for marine environments);

Silicon (Si) + Magnesium (Mg): Can be heat-treated and strengthened, resulting in high strength and ease of machining (e.g., 6-series aluminum-magnesium-silicon alloys, with a tensile strength of 250-400 MPa, suitable for structural parts);

Zinc (Zn) + Magnesium (Mg): Ultra-high strength (e.g., 7-series aluminum-zinc-magnesium alloys, with a tensile strength of 500-700 MPa, close to that of mild steel, suitable for aerospace applications). (II) Manufacturing Process and Morphological Characteristics
The manufacturing process for aluminum sheet is "aluminum ingot smelting → casting and rolling into billets → hot rolling/cold rolling → surface treatment → cutting and forming." Key process features include:
Hot-rolled aluminum sheet: The aluminum billet is heated to 400-500°C (below the melting point of aluminum) and rolled. The thickness ranges from 3 to 500 mm (extra-thick plates can be produced). The surface has an oxide scale and good toughness, making it suitable for thick-walled structural parts (such as molds and chemical equipment).
Cold-rolled aluminum sheet: Using hot-rolled aluminum sheet as raw material, it is rolled at room temperature. The thickness ranges from 0.1 to 3 mm. It has a smooth surface (roughness Ra ≤ 0.8 μm) and high dimensional accuracy (thickness tolerance ±0.01 mm). It is suitable for precision parts and decorative parts (such as home appliance panels and curtain wall panels).
Surface oxide film: When exposed to air, aluminum sheet naturally forms a dense, non-porous Al₂O₃ oxide film 5-10 nm thick. This film is resistant to room-temperature corrosion without the need for painting. Anodizing can increase the film thickness to 100 nm. 50-200nm, further enhancing corrosion resistance and decorative properties.

Common specifications for aluminum sheet: thickness 0.1-500mm (mainstream 0.3-10mm), width 1000-2000mm (customizable extra-wide sheets over 3000mm), length 1-6m (cut to length), and lightweight (e.g., a 1m×2m×1mm aluminum sheet weighs only 5.4kg, compared to 15.7kg for a steel sheet of the same size).
II. Core Classification of Aluminum Sheet (By Material and Process)
The classification logic for aluminum sheet revolves around "material performance" and "application scenarios." Clear functional boundaries corresponding to different categories are key to its wide adaptability:

(I) Classification by Material (Alloy Series) (Core Dimension)
Series 1 Pure Aluminum Sheet (approximately 15%)

Composition: Aluminum purity of 99.0%-99.9% (e.g., 1060 pure aluminum contains 99.6% aluminum), free of other alloying elements. Excellent electrical and thermal conductivity, corrosion resistance, and low strength (tensile strength ≤ 120 MPa).

Applications: Conductive components (e.g., transformer busbars, wire and cable cores), food contact parts (e.g., can bases, food packaging foil), and corrosion-resistant containers (e.g., pure aluminum storage tanks). Typical applications: 1060 aluminum sheet is used in household aluminum pots (for uniform thermal conductivity). 3 Series Aluminum-Manganese Alloy Sheet (Approximately 10%)

Composition: Contains 1.0%-1.5% manganese (Mn), no magnesium, cannot be heat-treated for strengthening, has medium strength (tensile strength 180-250 MPa), and offers superior corrosion resistance compared to pure aluminum sheet, especially seawater corrosion resistance.

Applications: Outdoor decorative panels (such as residential billboard panels), air conditioner radiators, and ship interior panels. Typical applications: 3003 aluminum sheet is used in air conditioner outdoor unit radiators (thermal conductivity and outdoor corrosion resistance).

5 Series Aluminum-Magnesium Alloy Sheet (Approximately 25%)

Composition: Contains 1.0%-5.0% magnesium (Mg), no silicon, cannot be heat-treated for strengthening, has high strength (tensile strength 200-350 MPa), good toughness, and excellent corrosion resistance (second only to pure aluminum sheet). It is the mainstay of "weather-resistant structural aluminum sheet."​
Applications: Marine engineering (such as ship decks and offshore platform steps), architectural curtain walls (exterior curtain wall panels), and transportation components (such as RV hulls). Typical applications: 5052 aluminum sheet is used for curtain wall panels in beachfront villas (salt spray corrosion resistant and maintenance-free).

6-Series Aluminum-Magnesium-Silicon Alloy Sheet (approximately 35%)

Composition: Contains 0.4%-1.0% silicon (Si) and 0.4%-1.0% magnesium (Mg). It can be strengthened through heat treatment (T6 temper), offers high strength (tensile strength 250-400 MPa), is easily processable (can be stamped, bent, and welded), and offers the best value, making it a "general-purpose structural aluminum sheet."

Applications: New energy vehicle components (such as battery housings and vehicle frames), building structural components (such as aluminum alloy door and window profile substrates), and electronic device housings (such as laptop computer housings). Typical applications: 6061 aluminum sheet is used for new energy vehicle battery housings (lightweight and high strength). 7-Series Aluminum-Zinc-Magnesium Alloy Sheet (approximately 5%)
Composition: Contains 5.0%-7.0% zinc (Zn) and 2.0%-3.0% magnesium (Mg). Heat-treatable and hardenable, it offers extremely high strength (tensile strength 500-700 MPa, close to that of mild steel), but exhibits relatively poor corrosion resistance (requiring surface treatment).
Applications: Aerospace components (e.g., aircraft fuselage skins, wing structures), high-end molds (e.g., precision stamping dies), and high-strength structural parts (e.g., bridge guardrails). Typical applications: 7075 aluminum sheet is used in drone fuselages (lightweight and ultra-high strength).
Other Specialty Aluminum Sheets
2-Series Aluminum-Copper Alloy Sheet: Contains 3.8%-4.9% copper (Cu), offers high strength but poor corrosion resistance, and is used in the military industry.
4-Series Aluminum-Silicon Alloy Sheet: Contains 4.5%-6.0% silicon (Si), has a low melting point, and is used in welding materials (e.g., aluminum welding wire substrates). (II) Classification by Rolling Process and Surface Treatment

By Rolling Process

Hot-rolled aluminum sheet: 3-500mm thick, with a rough surface (Ra ≤ 6.3μm), good toughness, and used for thick-walled structures (e.g., 50mm thick 6061 hot-rolled sheet for molds);

Cold-rolled aluminum sheet: 0.1-3mm thick, with a smooth surface (Ra ≤ 0.8μm), high precision, and used for precision parts (e.g., 0.5mm thick 6063 cold-rolled sheet for mobile phone midframes). By Surface Treatment (Derivative Product Category)

Anodized aluminum sheet: A thick oxide film (50-200nm) is formed through electrolysis. It can be dyed (gold, black, etc.), increasing corrosion resistance by 3-5 times. It is used for decorative purposes (such as hotel walls and furniture handles).

Spray-coated aluminum sheet: Surface-coated with fluorocarbon paint or polyester paint for excellent weather resistance (no fading for 15-20 years outdoors). It is used for building curtain walls (such as office building exteriors).

Laminated aluminum sheet: Surface-coated with PVC film for scratch resistance. It is used for home appliance panels (such as washing machine tops).

Brushed aluminum sheet: Surface-brushed (straight or random grain) for fingerprint resistance. It is used for electronic device casings (such as laptop computer covers).

III. Key Performance Advantages of Aluminum Sheet (Compared to Steel Sheet)

Aluminum sheet's performance advantages stem from its material properties. It precisely addresses the pain points of steel sheet: heavy, difficult to process, and poor thermal conductivity, making it suitable for lightweight and high-end applications:

Lightweight: 30%-70% weight reduction, lower energy consumption

Aluminum sheet has a density of only 2.7g/cm³, one-third that of carbon steel (7.85g/cm³) and one-third that of stainless steel (7.93g/cm³). Its weight is only 34% of that of steel for the same volume. For example, using 6-series aluminum sheet for the body frame of new energy vehicles can reduce vehicle weight by 40% and lower fuel consumption by 1.5-2L/100km. 7-series aluminum sheet, used in aviation for aircraft skins, is 60% lighter than steel skins, improving range. Naturally Corrosion-Resistant: Maintenance-Free, Lowering Costs

A dense, non-porous Al₂O₃ oxide film naturally forms on the surface of aluminum sheets. Under normal temperature and neutral conditions, the corrosion rate is only 0.0001mm/year (compared to approximately 0.1mm/year for carbon steel sheets, which require paint maintenance). The corrosion rate of 5-series aluminum-magnesium alloy sheets in seawater is 1/50 that of carbon steel, allowing for easy use without the need for paint. For example, a coastal building using 5052 aluminum sheet for curtain walling will remain rust-free for 20 years, with zero maintenance costs (compared to the average annual maintenance cost of 15 yuan/m2 for a carbon steel curtain wall). High Thermal and Electrical Conductivity: Suitable for Functional Components
Pure aluminum sheet has a thermal conductivity of 237W/(m・K), which is 5.2 times that of carbon steel (45W/(m・K)) and 14.8 times that of stainless steel (16W/(m・K)), making it suitable for heat sinks. Its conductivity is approximately 60% that of copper, but at only one-third the price, making it suitable for low-cost electrical applications. For example, using 1060 pure aluminum sheet in LED heat sinks offers four times higher heat dissipation efficiency than steel heat sinks, ensuring a doubling of LED lamp life. Easy to Process: Flexible Forming, Suitable for Complex Structures

Aluminum sheet has a low hardness (pure aluminum has a hardness of HB25-35, while carbon steel has a hardness of HB130-180). This allows for ultra-thin (0.01mm aluminum foil), ultra-wide (over 3000mm wide), and complex stamping (such as stretching cans). It can also be welded, bent, and cut, while consuming only 50% of the processing energy of steel. For example, a mobile phone middle frame made of 0.5mm thick 6063 cold-rolled aluminum sheet can be stamped into complex curved surfaces in a single press, with a scrap rate of only 1% (compared to approximately 5% for steel middle frames).

High Recyclability: Green and Low-Carbon

The recycling rate for aluminum sheet exceeds 95%, and the energy consumption of recycled aluminum is only 5% of that of virgin aluminum (recycling steel consumes 20% of that of virgin steel). Furthermore, the performance of recycled aluminum approaches that of virgin aluminum (purity exceeding 99.5%). For example, recycled cans can be re-rolled into 1060 aluminum sheet, which can then be used to make new cans, achieving a "closed loop" and reducing carbon emissions by 95% compared to using virgin aluminum.

IV. Key Application Areas of Aluminum Sheet

Aluminum sheet's lightweight and multifunctional properties make it suitable for a wide range of applications, including construction, transportation, electronics, and packaging. The core applications account for the following:

(I) Construction (approximately 30%)

Architectural curtain walls and decoration: 5-series aluminum-magnesium alloy sheet (0.8-3mm) is used for weather-resistant outdoor curtain walls, 6-series aluminum-magnesium-silicon alloy sheet (1.5-5mm) is used for door and window profile substrates, and anodized/spray-coated aluminum sheet is used for interior decoration (such as hotel walls and elevator panels). For example, the curtain wall of Beijing Daxing Airport uses 5052 spray-coated aluminum sheets (silver-gray), covering an area of ​​120,000 square meters, achieving a 40% weight reduction and 20-year weather resistance.

Roofs and Ceilings: 3-series aluminum-manganese alloy sheets (0.5-1.0mm) are used for factory roofs (corrosion resistance), and brushed aluminum sheets are used for shopping mall ceilings (aesthetically pleasing and fingerprint-resistant).

Structural Parts: 6-series aluminum sheets (5-20mm) are used for aluminum alloy scaffolding and curtain wall support keels (lightweight and easy to install).

(II) Transportation Sector (approximately 25%)

New Energy Vehicles: 6-series aluminum sheets (1.0-3.0mm) are used for battery casings (lightweight and high strength) and body panels (such as doors and hoods), and 5-series aluminum sheets (2.0-5.0mm) are used for chassis components (corrosion resistance). For example, the Tesla Model 3's battery casing uses 6061-T6 aluminum sheet, reducing weight by 30% and improving battery life.

Aerospace: 7-series aluminum sheet (2.0-10mm) is used for aircraft fuselage skins and wing structures (ultra-high strength + lightweight), while 1-series pure aluminum sheet (0.1-0.5mm) is used for aircraft conductor cores (conductivity).

Railway and Shipbuilding: 5-series aluminum sheet (3.0-8.0mm) is used for high-speed rail interior panels and ship decks (weather resistance), while 3-series aluminum sheet (1.5-3.0mm) is used for subway air conditioning radiators. (III) Electronics and Electrical Appliances (approximately 20%)
Consumer Electronics: 6-series aluminum sheet (0.3-1.0mm) for laptop cases and mobile phone midframes (lightness and strength); 1-series pure aluminum sheet (0.1-0.3mm) for LED heat sinks and power bank cases (heat conduction);
Home Appliances: 3-series aluminum sheet (0.4-0.8mm) for air conditioner outdoor unit radiators and refrigerator evaporators (heat conduction); and coated aluminum sheet (0.3-0.5mm) for washing machine tops and microwave oven cases (scratch resistance);
Industrial Appliances: 1-series pure aluminum sheet (1.0-5.0mm) for transformer busbars and distribution cabinet conductive plates (conductivity); 6-series aluminum sheet (2.0-8.0mm) for motor end caps (lightweighting). (IV) Packaging and Other Applications (Approximately 25%)

Packaging: Pure aluminum foil (0.005-0.1mm, ultra-thin aluminum sheet) is used for food packaging (such as chocolate foil) and pharmaceutical packaging (such as capsule aluminum-plastic sheet). 1-series aluminum sheet (0.2-0.5mm) is used for can bases (easily stretchable and corrosion-resistant).

Industrial: 6-series aluminum sheet (10-50mm) is used for precision molds (such as stamping dies) and chemical equipment (such as pure aluminum storage tanks). 5-series aluminum sheet (5-20mm) is used for offshore platform treads (salt spray resistant).

New Energy: 6-series aluminum sheet (0.1-0.3mm) is used for photovoltaic module backsheets (lightweight and weather-resistant). 1-series pure aluminum sheet (0.5-2.0mm) is used for conductive components in hydrogen energy equipment (conductive and hydrogen embrittlement-resistant).
V. Future Development Trends of Aluminum Sheet

With the advancement of the "dual carbon" goals and the upgrading of high-end manufacturing, aluminum sheet is developing towards "high strength, ultra-thinness and ultra-wideness, multifunctionality, and greenness":

High Strength: Breaking Through Structural Scenario Limitations

Developing "ultra-high-strength aluminum alloy sheet," such as 7-series aluminum-zinc-magnesium-copper alloy sheet (tensile strength ≥800 MPa), which approaches high-strength steel, is being used in aerospace applications (such as large passenger aircraft fuselages) and heavy truck frames (reducing weight by 50%). Microalloying (adding scandium and zirconium) is being used to enhance the strength of 5-series and 6-series aluminum sheet while maintaining corrosion resistance, enabling the replacement of more steel.

Structural parts.

Ultra-thin and ultra-wide: Suitable for precision and large-scale applications

Breakthroughs in "ultra-thin aluminum sheet" manufacturing technology, such as 0.005mm thick pure aluminum foil (only 1/10 the diameter of a human hair), for flexible electronic display substrates and lithium battery separators; development of ultra-wide cold-rolled aluminum sheet over 3000mm for large-scale building curtain walls (a single sheet covers an area of ​​up to 6 square meters, reducing seams) and high-speed rail carriage side panels (formed in one step, improving efficiency).

Functional Composites: Expanding Multi-Scenario Needs

Development of "multifunctional composite aluminum sheets": such as "thermal conductive + insulating" composite aluminum sheets (coated with an insulating film for electronic heat sinks), "antibacterial + corrosion-resistant" aluminum sheets (with silver ion additions for medical device casings), and "self-healing" aluminum sheets (which automatically repair damaged oxide films for long-term outdoor use); and promoting the integration of aluminum sheets with other materials (such as aluminum-steel composite sheets and aluminum-carbon fiber composite sheets), achieving both lightweight and high strength. Greening: Carbon Reduction and Circular Upgrading
Promote the "green aluminum smelting and rolling" process: Use renewable energy (photovoltaic and wind power) to electrolyze aluminum, reducing carbon emissions by 90% compared to thermal power aluminum; increase the proportion of recycled aluminum, with a target of 50% by 2030 (currently approximately 30%), and establish a closed-loop system of "aluminum sheet - scrap aluminum sheet - recycled aluminum sheet"; develop environmentally friendly surface treatment technologies such as chromium-free passivation and water-based spray coating to reduce heavy metal pollution.

Conclusion
Aluminum sheet, as a representative material of "lightweight + greening," not only addresses the pain points of steel sheet (heavy weight, high energy consumption, and difficult processing), but also achieves comprehensive upgrades in strength, corrosion resistance, and functionality through alloying and surface treatment, making it a "multifunctional carrier" for high-end manufacturing and consumer goods. From ultra-high-strength structural components in aerospace to lightweight battery casings for new energy vehicles, from weather-resistant decorative panels for building curtain walls to aluminum foil for everyday food packaging, aluminum sheet is present throughout the entire supply chain from high-end manufacturing to consumer goods and environmental protection. In the future, with breakthroughs in high-strength alloy research and development and green processes, aluminum sheet will further replace steel, becoming a core foundational material supporting the "dual carbon" goals and the upgrading of high-end manufacturing.