The inclusions removal in molten aluminum have a great impact on the aluminum plates, Degassing and slagging by degassing unit are important. In the process of feeding and stirring, the oxide film formed on the surface of the melt is damaged and mixed into the molten aluminum. Because the specific gravity of the oxide film is similar to that of the melt, the sedimentation is slow, and it is easy to enter the cast plate during casting. (Al2O3) is more polluting to metals. It has a high melting point. It exists in solid form in liquid aluminum. It is much harder than the matrix in cast-rolled sheets. As the amount of deformation increases, these places will appear similar to scratches.
When the machine is stopped, there are more slag and aluminum in the casting launder. When the slab is re-upped, these slags and aluminum (which have been oxidized) will cause the molten aluminum to enter the cast-rolled plate and affect the quality of the plate. In addition, because the aluminum silicate fiber felt will be damaged after the shutdown, which will cause partial fall off, these fall off will also enter the cast-rolled plate with the aluminum liquid in the next production. After cold rolling to a certain extent, surface quality problems will occur.
For the addition of the grain refiner Al-Ti-B, since the coarse TiAl3 agglomerates and TiB2 agglomerates cannot be completely dissolved during the time from the addition to the plate release, the agglomerates will be extended during the rolling process In strips, when it appears on the surface, after surface treatment, linear defects similar to scratches appear.
Since the casting nozzle material used is very easy to produce sintered products, after 40 to 60 hours of production, these sintered products are easy to fall off and enter the cast-rolled plate with the molten aluminum. The inclusions removal of the aluminum melt have a great impact on the use of aluminum plates, so it must be strictly controlled in production, and the following tasks should be done:
- Strict process management, do a good job of degassing and slagging in smelting.
- Pay attention to the use and maintenance of the runner, and replace the runner lining regularly.
- Pay attention to the addition of Al-Ti-B during operation, stir the adding part at any time, and beware of local deposition of Al-Ti-B.
- When selecting the caster tips and nozzles material, it must be noted that its material must have good high temperature resistance, and it is not easy to produce sintered products at high temperatures.
- Do a good job of degassing and slagging by degassing unit.
- Use ceramic foam filters to filter the aluminum melt and improve its purity.