Aluminum sheet: an all-round metal material in the era of lightweighting

1. Core classification and characteristics of aluminum plates
Classification by alloy system
Pure aluminum (1 series aluminum plate)
Typical grades: 1050, 1060, 1100, aluminum content ≥99%, total impurities (iron, silicon) <1%.
Performance advantages: density is only 2.7g/cm³, about 1/3 of steel plate, excellent electrical conductivity (61% IACS) and thermal conductivity (237W/m・K), strong atmospheric corrosion resistance (Al₂O₃ passivation film naturally formed on the surface).
Application scenarios: Aluminum foil substrate (thickness ≤0.2mm) is used for food packaging and pharmaceutical packaging; conductive busbars are used in the power industry; chemical equipment linings (such as concentrated nitric acid storage tanks).
Rust-proof aluminum (3 series, 5 series aluminum plates)
3 series (Al-Mn alloy): such as 3003, containing 1.0%~1.5% manganese, outstanding resistance to intergranular corrosion, and excellent formability. Commonly used in building curtain wall panels, can bodies (excellent deep drawing performance), and refrigerator evaporators.
5 series (Al-Mg alloy): such as 5052, containing 2.2%~2.8% magnesium, with a yield strength of 170MPa, and significant seawater corrosion resistance, used for ship decks, marine engineering structural parts, and lightweight automotive parts (such as door inner panels).
Duraluminum (2 series, 7 series aluminum plate)
2 series (Al-Cu-Mg alloy): such as 2A12 (LY12), with a tensile strength of ≥420MPa after aging treatment, is a traditional aviation aluminum plate used to manufacture aircraft skins and wing beams, but has poor corrosion resistance and requires anodizing treatment.
7 series (Al-Zn-Mg-Cu alloy): such as 7075, the strength can reach 572MPa (close to low alloy steel), often used in aerospace high-load parts (such as rocket fuel tanks) and high-end sports equipment (ski bottoms), but the weldability is poor, and riveting or bolting is mostly used.
Super hard aluminum (7 series improved)
Typical grade 7A04, with zinc and copper added, tensile strength exceeds 600MPa, used to manufacture aircraft landing gear and armored vehicle protective plates, but the plasticity is low, and the deformation needs to be controlled during processing.
Classification by production process
Hot-rolled aluminum plate
It is formed by high-temperature rolling (400℃~550℃), the thickness is usually >0.2mm, the surface has oxide scale, and the mechanical properties are uniform. It is used for architectural patterned plates and automobile fuel tank shells.
Cold-rolled aluminum sheet
Rolled at room temperature, with high thickness accuracy (tolerance ±0.01mm), smooth surface, can be further processed into foil or anodized, such as 5052 cold-rolled sheet (thickness 0.8mm~1.2mm) for mobile phone shells.
Cast aluminum sheet
Adopting die casting or sand casting process, it has a high silicon content (such as 10%~13% silicon in 3 series cast aluminum) and good fluidity. It is used to manufacture complex-shaped parts, such as automobile engine cylinder blocks and aluminum alloy wheels.
II. In-depth interpretation of key performance and application scenarios
Perfect balance between lightweight and high strength
Aviation field: Airbus A350 fuselage uses 5 series and 7 series aluminum sheets, which reduce weight by 15%~20% compared with traditional steel and improve fuel efficiency by 10%. For example, 7050-T7451 aluminum sheet (tensile strength 510MPa) is used to manufacture the wing main beam, and the deformation is less than 0.5mm when subjected to 3000N/m² aerodynamic load.
New energy vehicles: Tesla Model 3 body uses 6 series (Al-Mg-Si) aluminum sheet (6061-T6, tensile strength 310MPa), the body-in-white weighs only 270kg, 35% lighter than the steel body, and the cruising range is increased by 15%.
Corrosion resistance and environmental adaptability
Marine engineering: An offshore wind power platform in the South China Sea uses 5083-H116 aluminum sheet (containing 4.0%~4.9% magnesium). After chromate passivation treatment, the salt spray test (GB/T 10125) is 1000 hours without rust, and the service life is more than 25 years.
Building curtain wall: The exterior wall of Shanghai Tower is made of 3004-H16 aluminum plate (3mm thickness), with fluorocarbon spraying (PVDF coating) on ​​the surface, which has a weather resistance of more than 20 years and can resist typhoon (wind speed ≥50m/s) and acid rain (pH≤4.5) erosion.
Electrical conductivity, thermal conductivity and electromagnetic shielding performance
Power transmission: The busbar of high-voltage transmission lines is made of 1060 aluminum-magnesium-silicon alloy plate (conductivity ≥61% IACS), and the current carrying capacity is 70% of the copper busbar with the same cross-section, but the weight is only 1/3, and the cost is reduced by 40%.
Electronic equipment: Huawei server shell uses 1050 aluminum plate (1.5mm thickness). After chemical nickel plating, the electromagnetic shielding efficiency reaches 80dB (at 1GHz frequency), meeting the FCC Class B standard.
3. Processing technology innovation and technological breakthroughs
Surface treatment technology upgrade
Anodizing process
Traditional sulfuric acid anodizing: oxide film thickness 5μm~20μm, hardness HV 300~500, used for architectural decoration (such as door and window profiles), corrosion resistance is 5 times higher than that of untreated plates.
Hard anodizing: treated in low temperature (-5℃~5℃) oxalic acid solution, the film thickness can reach 50μm~150μm, hardness HV 500~800, used for automobile engine piston rings and aviation bearing seats.
New coating technology
Ceramic coating: Al₂O₃-TiO₂ composite film is formed on the surface of aluminum plate by sol-gel method, and the wear resistance is 3 times higher than that of ordinary anodized plate, which is used to protect the lens of mobile phone camera.
Self-cleaning coating: Fluorocarbon coating with nano-TiO₂ added can decompose surface organic matter under ultraviolet light, and the cleanliness rate reaches 95% after rainwater washing, which is used in curtain walls of high-rise buildings.
Forming process innovation
Superplastic forming technology
Heating 7075 aluminum plate to 450℃~500℃ and controlling the strain rate below 10⁻³/s can achieve complex curved surface forming (such as aircraft air intake shell), with material elongation of more than 500%, reducing welding process by 80%.
Electromagnetic pulse forming
Through strong magnetic field pulses (peak current 100kA), the aluminum plate is fitted to the mold within μs time, which is used to manufacture automobile anti-collision beams (5052 aluminum plates). The forming accuracy reaches ±0.1mm, and the production efficiency is 5 times higher than that of traditional stamping.
IV. Market dynamics and green development trends
Demand explosion in the new energy field
Photovoltaic brackets: In 2025, the global demand for aluminum plates for photovoltaics will reach 3 million tons. Due to its weather resistance and lightweight advantages, the penetration rate of 6063-T5 aluminum plates (tensile strength 215MPa) in tracking brackets will increase from 30% in 2020 to 65%.
Energy storage battery: CATL uses 1060 aluminum plate (thickness 0.3mm) to make battery shells, and achieves sealing through laser welding (leakage rate <10⁻⁹Pa・m³/s), which reduces weight by 40% compared with steel shells and improves heat dissipation efficiency by 20%.
Deepening the application of recycled aluminum
In 2025, the proportion of recycled aluminum in domestic aluminum plate raw materials will reach 45% (compared with 2020 + 15%). An aluminum company adopts the "crushing-smelting-refining" short process. The energy consumption of recycled aluminum plates is 80% lower than that of primary aluminum, and CO₂ emissions are reduced by 90kg/ton.
The EU's "New Battery Law" requires that the proportion of recycled aluminum in battery shells be ≥60% in 2027, and promotes the application of 5 series recycled aluminum plates (such as 5754) in the field of power batteries. At present, mass production has been achieved in China (impurity Fe content <0.1%).
5. Future Technology Development Direction
Nano-reinforced aluminum alloy plate: Add 0.5%~1.0% nano Al₂O₃ particles to increase the strength of 7 series aluminum plate by 20%, while maintaining elongation ≥10%, and aim to be applied to the fuselage of the next generation of large aircraft (such as C919 modification).
Multifunctional composite aluminum plate: Surface integrated photocatalysis (TiO₂) + self-cleaning + conductive functions, used for building integrated photovoltaic (BIPV) curtain wall, power generation efficiency of 15%, while decomposing NOx in the air (purification efficiency ≥80%).
Digital twin manufacturing: Through ANSYS simulation of grain growth during aluminum plate rolling (grain size control above ASTM 8 level), the new product development cycle is shortened from 12 months to 6 months. For example, the stamping pass rate of 6 series automotive aluminum plate developed by a certain company has increased from 75% to 98%.