The process of aluminum sheet manufacturers and aluminum coil manufacturers affects the price of aluminum coils

A process used for aluminum alloy sheets with high yield strength and suitable ductility, especially for manufacturing automotive panels. This process involves casting an aluminum alloy that has not undergone heat treatment into a billet, which is then rolled through a series of processes to obtain the final specification of the plate. A better option is to produce recrystallization after subsequent heat treatment. The rolling process includes hot rolling and medium temperature rolling of the cast billet to obtain intermediate thickness products, followed by cooling of the intermediate products, followed by medium temperature rolling and cold rolling of the intermediate products within the range of room temperature to 340 degrees Celsius to obtain the final specifications of the plate. This series of rolling processes involves continuous winding without intermediate products and complete annealing of intermediate plates. The invention also relates to thin sheets of alloy products.

The present invention relates to a process flow of aluminum sheet metal. In particular, the present invention relates to sheets suitable for forming from unheated alloys by rolling. For example, in the manufacturing of automotive panels, the 5000 series aluminum alloy.

The 5000 series aluminum alloy (with magnesium as the main alloying element) is commonly used in automotive panels (such as protective panels, door panels, covers, etc.), providing high yield point and high ductility for alloy sheets for such applications. Aluminum alloy sheets with appropriate specifications and yield strength can be obtained by rolling after continuous casting. In the traditional continuous casting process, the metal obtained from casting is hot rolled and warmed, then coiled (at a temperature of approximately 300 degrees Celsius) and sent to another rolling mill for final cold rolling at a temperature not exceeding 160 degrees Celsius.

In order to refine, the point to be mentioned here is that the commonly referred to 'hot rolling' is carried out when the temperature is higher than the recrystallization temperature of the alloy. So that the alloy can self anneal and recrystallize between the roll gaps or in the coil after rolling. The term 'cold rolling' usually means working rolls with a large work hardening rate so that the alloy neither recrystallizes nor recovers during or after rolling. The "medium temperature rolling" is performed between the two, so that there is no recrystallization effect but the yield strength is significantly reduced due to the recovery process. For aluminum alloys, the hot rolling temperature exceeds 350 degrees Celsius, the cold rolling temperature is less than 150 degrees Celsius, and medium temperature rolling is carried out between 150 and 350 degrees Celsius.

Unfortunately, the intermediate winding of the conventional methods mentioned above is cumbersome and expensive, and storage and transportation require obtaining a product with a suitable microcrystalline structure to achieve the expected yield strength.

On May 7, 1996, a coaxial continuous casting process was disclosed in the US version 5514228, in which the plates were not rolled into the final required specifications through intermediate winding. However, further solution treatment is required before the final rolling to ensure that the plates are continuously and completely annealed before the final winding. However, the 5000 series alloys will not be strengthened after solution treatment.

One purpose of the present invention is to conveniently and economically produce aluminum alloy sheets without heat treatment, suitable for the manufacturing of automotive panels.

Another object of the present invention is to provide a process for obtaining high yield point aluminum alloy products by continuously rolling 5000 series aluminum alloy plates in steps without intermediate secondary rolling.

One aspect of the present invention provides a process for producing aluminum alloy sheets, which includes casting aluminum alloy without heat treatment to form a flat steel ingot, which then undergoes a series of rolling steps to produce the final specification product. The rolling steps include: hot rolling and medium temperature rolling of the slab to form intermediate specification intermediate plates and cooling intermediate plates; Then, the intermediate plates are rolled and cold rolled at medium temperature within the temperature range of room temperature to 340 degrees Celsius; A series of continuous rolling steps without intermediate plates for winding or complete annealing.

The above process is an alloy in the so-called H2 tempering. Further annealing and recrystallization are suitable for plates used in automobiles.

Another aspect of the present invention is to provide an aluminum alloy sheet made of aluminum alloy without heat treatment, which includes casting aluminum alloy without heat treatment to form a flat steel ingot; The flat steel ingot undergoes a series of rolling to produce the final specification of the product; The rolling steps include: hot rolling and medium temperature rolling of the slab, forming intermediate intermediate plates, cooling the intermediate plates, and then conducting medium temperature rolling and cold rolling of the intermediate plates within the temperature range of room temperature to 340 degrees Celsius; A series of continuous rolling steps without intermediate plates for winding or complete annealing.

As mentioned above, the present invention requires hot rolling and medium temperature rolling, followed by medium temperature rolling and cold rolling without intermediate winding or complete annealing. When continuously rolling flat steel ingots, the hot slab loses heat to the air and the rollers, so that the hot rolling ends in medium temperature rolling (i.e. below the crystallization temperature).

This is the method of hot rolling and medium temperature rolling. During hot rolling, the metal is completely recrystallized to release any strain energy generated during casting. The temperature during this period depends on the amount of concurrent cold working and the composition of the alloy. During medium temperature rolling, strain energy is established due to gradual rolling, which is what metals call "recovery". Like recrystallization, the degree of recovery affected by the exit temperature depends on the amount of cold work and the composition of the alloy. The important difference between recrystallization and recovery is that the recrystallization effect causes a rapid reduction in internal tension and occurs during hot rolling. However, recovery occurs throughout the entire cycle of medium temperature rolling and cold rolling, and the internal tension decreases smoothly, but most of the pressure is released during the "warm" rolling period.

The process of the present invention is beneficial for any aluminum alloy that has not undergone heat treatment, and the final treatment of these aluminum alloys is in a fully annealed state. However, strengthening grain size is the most important among the 5000 series alloys in automotive applications. The process can be used for transporting all 5000 series alloys in a fully annealed state, but it is particularly useful for AA5754 alloy, which contains a limited amount of Mg. To avoid stress corrosion cracking, strengthening grain size is particularly important for this alloy. For example, AA5182 alloy with higher Mg content is sensitive to stress corrosion cracking, but they have higher strength. Of course, it is beneficial for such alloys, but it is not so obvious.

The process of the present invention, at least in its preferred form, provides a 5000 series aluminum sheet for manufacturing automotive body structures, which obtains good mechanical properties through continuous rolling on a continuous casting machine.

An advantage of the present invention is that although self annealing does not optimize the microstructure and properties, recrystallization after rolling at lower temperatures and subsequent annealing do indeed result in the expected fine particle size, high strength, and favorable crystal texture.

1. A process for aluminum alloy sheets, which includes casting aluminum alloy without heat treatment to form a flat steel ingot, which then undergoes a series of rolling steps to produce the final specification of the product. The rolling steps include: hot rolling and medium temperature rolling of the slab to form intermediate specification intermediate plates and cooling intermediate plates; Then, the intermediate plates are rolled and cold rolled at medium temperature within the temperature range of room temperature to 340 degrees Celsius; A series of continuous rolling steps without intermediate plates for winding or complete annealing.