7A04 aluminum alloy is heat-treated strengthening alloy, its strength is higher than that of hard aluminium. Its yield strength is close to tensile strength and plasticity is low. Its sensitivity to stress concentration is strong, especially under vibration load and repeated static load. Therefore, the design, manufacturing and assembly processes of parts need to strictly avoid stress concentration and stress factors of process accessories. The heat resistance of the alloy is poor, and it will soften sharply when the temperature is higher than 125 C. The stress corrosion resistance of thick parts in short and transverse direction is poor.
7A04 aluminum alloy is widely used in the main force parts of aircraft structure, such as girder, truss, partition frame, skin, wing rib, joint, landing gear parts, etc. It can produce various semi-finished products, such as sheets, strips, profiles, bars, wallboards, pipes, wires, free forgings and die forgings.
Large semi-finished products, especially large and complex forgings, die forgings and profiles, must carefully check their transverse properties and apply more perfect manufacturing procedures to improve their transverse properties. In addition, all kinds of non-destructive testing should be carried out to ensure that the defects are within the allowable range.
The plasticity of
7A04 aluminum alloy in annealing and new quenching state is similar to that of 2A12 alloy in the same state. The plasticity of material in T6 state decreases obviously, but it is allowed to be calibrated, which can be carried out after cold state or preheating. The alloy has good spot welding performance, excellent friction stir welding performance, non-gas welding, and good machinability.
