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In order to meet these stringent standards, various vehicles, including family cars, must lose weight, which forces automakers to consider new materials, and the process development and production application of aluminum alloy body sheets have developed rapidly.

The aluminum alloys used for automobile body sheets in Europe mainly include 5××× and 6××× series alloys, of which 5××× series have higher strength and are mostly used as inner plates and internal structural plates, and 6××× series are mostly used for Outer panel. Since the 1940s, Alcoa, Alusuisse, Alcan and other famous aluminum processing companies have successively cooperated with automobile companies including British Leyland, Ford and JaguarLand Rover. Cooperation, they have done a lot of work in the research and development of aluminum alloy body panels, they have developed a set of detailed parameters for each step of the production process, the purpose is to be tied to the customers they supply, making it difficult for other manufacturers to supply these manufacturers. goods. For example, AA6016A products have very strict requirements in different ranges, and require additional surface treatment, such as electric spark texturing (EDT) surface and stable passivation layer, which leads to the need for at least 5 It took years to pass the certification, which caused great resistance for other aluminum processing companies to enter the European and American aluminum alloy automotive sheet market.

The production process of automobile sheet is as follows: semi-continuous casting, milling, hot rolling, cold rolling, continuous solution heat treatment, finishing and surface treatment (cleaning, passivation, wet or dry oiling, straightening). Among them, the casting, hot rolling and cold rolling stages are similar to many cases of can production. The bottleneck of the processing process lies in the continuous solution heat treatment stage (6××× series alloys and a few 5××× series alloys require solution heat treatment). Therefore, The production capacity of automotive sheets depends on these production lines. A typical continuous solution treatment line includes: an uncoiler (possibly with an in-line roll leveler), a looper (which can store a sufficient amount of coil material when unloading or changing coils). The strip is then heated in a furnace, typically at a temperature of 550-600°C, followed by rapid quenching and coiling. Coiling is carried out in a controlled state to achieve stable pre-aging, eventually reaching the T4 state, at which point the material becomes stable, soft, and has good formability.

The heat treatment is followed by a series of surface finishing processes. The strip is chemically or electrolytically cleaned, rinsed, and then stabilized with fluozirconic acid and fluotitanic acid to prevent further oxidation, allowing the sheet to have a stable surface for at least 6 months prior to use by the manufacturer. After passivation treatment, the sheet is rolled or sprayed with a dry lubricating film to increase the formability when stamping the panel, then dried and coiled. The supply form may be cut sheets or coils according to the requirements of different manufacturers.