Aluminum alloy plate is a highly versatile material created by adding various alloy elements (primarily copper, silicon, magnesium, zinc, manganese, and secondary alloy elements such as nickel, iron, titanium, chromium, and lithium) to improve its mechanical performance and chemical properties during aluminum plate processing. Aluminum alloy plates possess special properties that pure aluminum plates do not have, and are widely used in special environments, such as in ships, refrigerators, molds, and aerospace equipment.
The formability of a sheet is its ability to withstand changes in shape during stamping. The formability of aluminum alloy plates can be evaluated through formability tests, and their results fully meet the needs of automotive performance requirements.
Excellent surface finish
Aluminum alloy plates have a greater crystal size than steel plates. Unequal grain sizes under coarse crystals can lead to uneven deformation on the surface of the stamped parts in the rolling direction, resulting in surface defects known as "rope lines." This can cause inconsistent surface luster after painting, so aluminum alloy plates used in automobiles need to have excellent surface finish.
Certain anti-aging stability
The feature of an aluminum alloy plate that does not age at room temperature is called anti-aging stability. Aging can cause alloys to yield elongation points or Lüders bands during tensile deformation, resulting in uneven surface deformation and wrinkling during stamping, which affects the appearance of stamped parts. The material from production to stamping usually requires some time for transportation and storage at room temperature. It is generally required that the material undergoes no aging for six months in storage.
Good bake hardenability
Stamping parts in vehicles undergo aging during painting and baking to increase their yield strength, which is called bake hardenability. A high bake hardenability gives a part high resistance to dents. Since most automotive paint baking processes are designed for steel plates, the bake hardenability of aluminum alloy plates needs to be compatible with the paint process designed for steel plates. The bake hardenability of the material can be evaluated according to relevant standards.
Good flanging ductility
The characteristic of aluminum alloy plates resisting cracking during flanging in stamped automotive exterior panels is called flanging ductility. Aluminum alloy plates need to have good flanging ductility to ensure that they do not crack during flanging. Flanging ductility is related to the total elongation of the plate and the internal structure of the material. Cold bending tests can be used to detect flanging ductility, but typical cold bending tests do not consider strain rate sensitivity, and flanging during stamping involves rapid deformation and a large strain rate, requiring higher demands for flanging ductility.