What is the process of rolling aluminum? Recent technological advances in the aerospace, automotive, marine, and construction industries have led to increased demand for materials with high strength / weight ratio, high specific modulus, good corrosion resistance, and good thermal conductivity. Aluminum and its alloys offer a combination of enormous properties.
The processing of aluminum alloys from casting to the final product is associated with several metallurgical events. For further refining and optimization of process paths and alloys, a comprehensive understanding of mechanical-thermal processes with experimental observations and physical modeling is required.
Rolling is a mechanical process that is involved in many metalworking operations. Rolled aluminum products are the basic materials for our daily lives. Thin products are used as packaging materials such as thick products, aluminum cans and aluminum sheets as structural elements for railway vehicles and aircraft.
Rolled products, namely plates, sheets and foils, make up approximately 50% of the total aluminum alloys used. In North America, the packaging industry uses most sheets and foil to make beverage cans, foil containers, and foil packaging. This sheet is also used in roofing and facades, for aircraft structures, road and rail vehicles, in transportation, including offshore platforms, and superstructures and hulls.
Also, relatively little is currently used in the production of high-volume vehicles, it is expected that in the next decade the sheet used for space frames and body panels will be used, a market that can easily fit 2 million tons. In the drink frame. boxes. Used in the manufacture of aerial frames, military vehicles and bridges, ship superstructures, refrigeration and chemical containers, and plastic products. Other uses for packaging foil include foil for electrical equipment, building insulation, lithographic plates, and heat exchangers.
Shows the production processes of extruded aluminum products. Rolling equipment is divided into approximately three types. That is, hot rolling mills, cold rolling mills and foil mills. In general, rolling is done by applying a load to the material by pressing it vertically along a pair of rolls. Work rolls deform due to the high load rolling process. As a result, the rolled strips are distorted. To solve this problem, one or more additional rollers are installed at the top and bottom of each working roller to reduce deformation.
Hot rolling is done at the highest possible temperature to reduce the loads and reduce the flow stress to achieve a large reduction. Due to the need to re-control the crystallization and precipitation, depending on the alloy as well as the aggregation, a high temperature limit is applied.
During normal rolling, the coarse structure transforms into a bulk structure and recrystallizes to a finer grain size. The primary sediments are coarsely crushed and evenly distributed. Decreasing the temperature during rolling and increasing the vacuum concentration in the network due to deformation leads to more precipitation of the secondary phases.
Due to the microstructure, hot rolling deformation and annealing steps are observed sequentially. The predominant metallurgical properties are recrystallization and development of crystal (texture) orientations. Both processes are interconnected and affected by continuous rainfall
. Recrystallization is mainly determined by the alloy system and processing conditions. In high purity aluminum, the grain boundary mobility is high and the material already shows rapid recrystallization during processing (dynamic recrystallization).
Conventional industrial alloys, dynamic recrystallization can be observed at very high temperatures, this effect is not only due to nucleation and growth, but mainly due to local swelling of the grain boundary. For these materials, recrystallization usually occurs at standstill or after rolling at high temperatures (after dynamic or static recrystallization).
In commercial pure alloys such as AA1050, which is commonly used for foil or lithographic sheet packaging, low-solubility elements such as Fe and Si interact with the grain boundaries to prevent recrystallization in the presence of finely dispersed sediments.
The presence of manganese and chromium gives the same effect as long as the elements are not attached to large particles. In the Al-Mg-Mn alloy system, which is used in significant quantities for beverage cans or automotive components, recrystallization covers a wide range of industrial conditions and can therefore be greatly influenced by the choice of rolling parameters. . In industrial practice, the recrystallization structure can be obtained in a separate annealing process, but more advanced technologies use the rolling temperature on the coil.
In a typical hot mill, aluminum ingots are dipped in kilns before being brought to the reverse mill or shredder to make a long, narrow strip. The tape is significantly reduced, we bring it to the Finishing Mill, which is a series of rolls downstream of the same line, and is reduced to the final thickness before it is wrapped at the end of the process.
A continuous rolling line creates a continuous thin slab that progresses in a continuous process, all in one, through a coarse mill mill and then an end mill. Slab mill has a separate crushing mill and finishing factory. The plate is repeatedly passed under the same mill to obtain the final thickness.
Shows sample configurations of hot rolled aluminum plants. The configuration of rolling mills varies depending on the amount of production desired. Single-base mills are used to produce small batches of a wide range of products, while standing mills are used for mass production.
In recent years, it has become very significant to start working with single-mill mills to add rolling mills in line with growing demand to minimize initial investment and shift standing plants.
Hot rolling mills for aluminum have coil coating problems because the adhesion of aluminum powder to the surface of the coils affects the surface quality of the rolling strips. Brush rolls and other special mechanisms are installed in aluminum rolling mills as countermeasures against such a problem.