Aluminum, magnesium, titanium and other metals with small density are usually called light metals, and the corresponding aluminum, magnesium and titanium alloys are called light alloys. The special excellent properties and development potential of light alloy make the world pay more and more attention to the research, development and application of light alloy materials.
1. Concept and definition of
aircraft grade aluminum sheet
Aircraft grade aluminum sheet is a kind of ultra-high strength deformed aluminum alloy, which is widely used in aviation industry. Compared with ordinary aluminum alloy, aluminum alloy for aircraft has higher requirements on strength, hardness, toughness, fatigue resistance and plasticity. Aviation aluminum alloy has good mechanical and processing properties, good plasticity after solution treatment and good heat treatment strengthening effect. Generally, it has high strength and toughness below 150 ℃ (or even higher), so it is an ideal aviation structural material.
There are many kinds of aluminum alloys used in airplanes. At present, the aluminum alloy used in aircraft structure in the world is mainly high-strength 2 series (2024, 2017, 2A12, etc.) and ultra-high-strength 7 Series (
7075,
7475,
7050,
7A04, etc.), in addition, there are some 5 Series (5A06, 5052, 5086, etc.) and 6 Series (6061, 6082, etc.) and a small number of other series of aluminum materials.
2. Basic characteristics of
aircraft grade aluminum sheet
The main characteristics of aluminum alloy for aerospace are: large-scale and integrated, thin-walled and lightweight, precision of section size and geometrical tolerance, homogenization and quality of structure and properties. According to the different service conditions and parts of the aircraft, the main aluminum alloys used in aerospace are high-strength aluminum alloy, heat-resistant aluminum alloy and corrosion-resistant aluminum alloy. High strength aluminum alloy is mainly used in aircraft fuselage parts, engine room, seats, control system, etc., which is the most widely used.
The biggest characteristic of
aircraft grade aluminum sheet is that it can improve its strength through deformation heat treatment. Deformation heat treatment is a comprehensive process which combines the deformation strengthening of plastic deformation with the phase transformation strengthening of heat treatment to unify the forming process and forming performance. In the plastic deformation process of aviation aluminum alloy, the defect density inside the crystal increases, and these crystal defects will cause the change of the microstructure inside the material. In the process of plastic deformation of aviation aluminum alloy, there will be dynamic recovery, dynamic recrystallization, sub dynamic crystallization, static recrystallization, static recovery and other crystal structure changes. These changes of crystal structure, if properly controlled, will significantly improve the mechanical properties and enhance the service life of the material.
3. Classification of
aircraft grade aluminum sheet
There are many kinds of classification methods of aluminum alloy. According to the processing methods, aluminum alloy can be divided into deformation aluminum alloy and casting aluminum alloy. Deformation aluminum alloy can withstand pressure processing, can be processed into various forms and specifications of aluminum alloy, mainly used in the manufacture of aviation equipment. Deformation aluminum alloy is divided into non heat treatment strengthening aluminum alloy and heat treatment strengthening aluminum alloy. The non heat treatment strengthening aluminum alloy can not improve the mechanical properties through heat treatment, but can only be strengthened through cold working deformation. It mainly includes high-purity aluminum, industrial high-purity aluminum, industrial pure aluminum and antirust aluminum. Heat treatable strengthening aluminum alloy can improve its mechanical properties by means of heat treatment such as quenching and aging. It can be divided into duralumin, forged aluminum, super duralumin and special aluminum alloy. Aviation aluminum alloys are mainly deformable aluminum alloys that can be heat treated, such as 2000 and
7000 series aluminum alloys.
4.
Aircraft grade aluminum sheet application
According to reports, the launch cost of space vehicles entering the air will be saved about US $20000 for each 1kg reduction, so the structural weight reduction in the space field can be described as "gram calculation". If the fighter's weight is reduced by 15%, the aircraft's running distance can be shortened by 15%, the range can be increased by 20%, and the payload can be increased by 30%. Therefore, countries all over the world attach great importance to the research and development of lightweight structural materials for aerospace.
Aircraft grade aluminum sheet is widely used in the field of Aeronautics and Astronautics because of its unique advantages, such as small density, moderate strength, easy processing and forming, strong corrosion resistance, rich resources and strong recyclability. The skin, beam, rib, truss, partition frame and landing gear of the aircraft can be made of aluminum alloy. The passenger compartment, front fuselage, middle fuselage, rear fuselage, vertical tail, flap, lift aileron and horizontal tail of the space shuttle are all made of aluminum alloy. The amount of aluminum used in airplanes varies according to their use. Due to the low price of aluminum alloy, a large number of civil aircrafts focusing on economic benefits are used. For example, the aluminum alloy used in Boeing 767 aircraft accounts for about 81% of the body structure weight. Some aviation aluminum alloys have good low temperature properties and can work in liquid hydrogen and liquid oxygen environment, so they are good materials for making liquid rockets. The fuel tank, oxidizer tank, inter tank section, interstage section, tail section and instrument cabin of Saturn 5 launch vehicle launching Apollo are all made of aviation aluminum alloy.
At present, the main aluminum alloy materials used in civil aircraft are: aluminum alloy casting, aluminum alloy forging, large section aluminum alloy extrusion profile,
aircraft grade aluminum sheet and aluminum lithium alloy.
2024 aviation aluminum alloy is used for aircraft structural parts. 2048 aviation aluminum alloy is mainly used for manufacturing aerospace structural parts and weapon structural parts. 2218 is mainly used for piston of aircraft engine and diesel engine, cylinder head of aircraft engine, impeller of jet engine and compressor ring. 2219 aluminum is used for welding oxidizer tank of space rocket, skin and structural parts of supersonic aircraft.
7049 is used for aircraft and missile parts such as landing gear hydraulic cylinders and extrusions.
7050 aviation aluminum alloy is used for medium and thick plates, extrusions, free forgings and die forgings of aircraft structural parts. 7178 aviation aluminum alloy is used to manufacture aerospace parts with high compressive yield strength. 7475 is used for fuselage plate, wing frame, truss, etc. 7A04 is used for aircraft skin, screws, and load-bearing components such as girder truss, spacer frame, wing rib, landing gear.
