After aluminum melting refining in the static furnace for 30 minutes, the bubbles generated by the refining in the melt will carry hydrogen that diffuses into the bubbles and the oxidized slag adhered to the surface during the rising stage of the bubbles overflows the liquid surface. For low-grade products that are generally required, When the modifier is added in the smelting process, it can enter the casting process. However, for high-end products, online refining and online filtration are required to further purify the melt. At the same time, it is best to use an online modification method, so that the modifier is added about 15 minutes before casting, and then enters the casting process.
The molten aluminum has enough time in the aluminum melting refining process, as long as the gas content of the molten aluminum entering the refiner is less than 0.18ml/(100g A1), the refining agent used is pure and effective, and the gas content of the aluminum melt after online refining It can reach below 0.10~0.12ml/ (100g A1), which can fully meet the requirements of producing high-quality double zero aluminum foil.
However, in casting, the situation is different from casting and rolling. One is that the flow rate is large. The soft alloy is more than 3.8 times that of casting and rolling, and the hard alloy is also more than 2.5 times that of casting and rolling. The action time of the soft alloy is only 4.7min, and the hard alloy is only 7.2min. The refining effect is far less than that of casting and rolling. The second is that the alloy composition is complex and the content is high. The content of the alloy melt is much higher than the pure casting. The gas content of aluminum, under normal circumstances, after the aluminum melt in the standing furnace is refined, the gas content of pure aluminum is 0.14 0.16 mL/ (100g A1), while 7075 alloy has 0.28 mL/ (100g A1) ) Above, this shows from another aspect that it is more difficult to reduce the gas content in 7075 alloy.
Now some aerospace materials require the gas content of 7075 alloy melt to be controlled at 0.08mlL/(100g A1), which is difficult to achieve. It requires a reasonable design of the structure, capacity, rotor speed of the degassing device, the purity and activity of the refined gas, and the need to adopt a dual-rotor structure, use high-purity and active refining gas, appropriately expand the capacity, and extend the aluminum liquid in the refiner. The effective time in the middle can guarantee the effect of online refining.