The mill finish aluminum generally has two types: hot rolling aluminum and cast rolled aluminum. The hot rolling aluminum alloy plate usually refers to rolling at a temperature higher than the crystallization temperature of the metal. Compared with general cast-rolled products, hot-rolled aluminum plates not only ensure good surface quality, but also have strong ductility and mechanical properties, and the anodizing effect is also very good.
Differences between hot-rolled aluminum plates and cast-rolled aluminum plates
1. Price
Cold-rolled aluminum plates are simple to process and cheaper than hot-rolled aluminum plates. Since hot-rolled aluminum plates need to undergo hot rolling, the process requirements and costs are higher, and the price will be higher accordingly.
2. Differences in billet supply
The billet supply process for hot-rolled aluminum plates is generally: aluminum ingots → smelting and casting into flat ingots → milling surface → uniform annealing → hot rolling into aluminium plates and strips.
The billet supply process of cold-rolled aluminum sheet is generally: aluminum ingot → melting → rolling into aluminum sheet by casting and rolling machine.
Comparing the billet supply processes of the two, it can be seen that the casting production efficiency of cold-rolled aluminum plates is relatively high. However, the composition deviation and impurity inclusion problems of cold-rolled aluminum plate billets are difficult to solve. Therefore, from the overall quality point of view, cold-rolled billets are not as good as hot-rolled billets.
3. Different production processes
Cold-rolled aluminum sheets are first processed by a casting mill into a cast-rolled coil and then processed by a cold rolling mill, while hot-rolled aluminum sheets are made by heating aluminum ingots (400-500mm thick) at high temperature and then rolling them by a hot rolling mill.
4. Different performance
Hot-rolled aluminum plates have good surface quality after high-temperature treatment, and have strong ductility and mechanical properties.
5. Different uses
Cold-rolled aluminum sheets are mostly used in the mold field, while hot-rolled aluminum sheets are suitable for high-strength work such as stamping and stretching.
6. Finished product differences
The elongation of cold-rolled products is usually lower than that of hot-rolled products.
Depending on the purpose, the technical requirements for aluminum plates are different, but they still have some common technical requirements:
1. Fine structure and uniform performance
For thick plates, especially ultra-thick plates, the performance in the thickness direction is required to be uniform, and no large performance fluctuations are allowed; for medium and thick plates and thin strips, there must not be large performance fluctuations in the length and width directions. There are corresponding special control standards for aluminum plates of different uses and specifications.
2. High dimensional accuracy
It mainly includes thickness accuracy and width accuracy. The most difficult and strict requirement is thickness dimensional accuracy, which affects the performance or subsequent processing procedures.
3. Good plate shape
Plate shape includes flatness and plate convexity. Aluminum plate thickness is sometimes also called plate shape, which is mainly manifested in wave type or warping, while plate convexity refers to the degree of deviation of the cross section from the rectangle, which will seriously affect the forming and processing performance and use performance.
4. High surface finish
Aluminum metal sheet is widely used in packaging, printing, construction and other industries. Therefore, they must have good surface quality and must not have surface defects such as inclusions, pressed objects, black and white stripes, scratches, etc.