| 7075 aluminum alloy belongs to Al-Zn-Mg-Cu aluminum alloy, which is widely used in aerospace and other fields because of its advantages, such as high strength, low density and good corrosion resistance. The traditional method of producing 7075 aluminum alloy sheets is hot rolling, which has long procedure, big equipment investment and high production cost. Roll-casting process for 7075 aluminum alloy has a lot of advantages such as simple production process, low equipment investment, energy saving and environmental protection. But it is difficult for 7075 aluminum alloy to be roll-cast because of its physical properties. In this paper, the effects of complex fields and Al-Ti-B refiner on the microstructure of 7075 aluminum alloy are studied by applying ultrasound, pulse current, static magnetic field and the complex fields of them in the cast-rolling process of 7075 aluminum alloy. A series of results are obtained as follows:(1)In the condition of common cast-rolling, the microstructure of 7075 aluminum alloy is nonuniform and. And the grains of the 7075 aluminum alloy which has a obvious phenomenon of segregation are also coarse.(2)The complex fields of ultrasound whose frequency and power are 20KHz and 2000 W, pulse current whose frequency^ peak current and duty cycle are 20Hzã€300A and 15%, static magnetic field whose size is 30mT have the best effect to refine the microstructure of 7075 aluminum alloy and abate the cast-rolling segregation.(3)Adding the Al-Ti-B refiner whose content is 0.2% has an obvious effect to refine the microstructure of 7075 aluminum alloy in the common cast-rolling condition and the complex fields condition.(4)Adding the complex fields of pulse current whose frequencyã€peak current and duty cycle are 20Hzã€300A and 15% and steady-state magnetic field whose size is 30mT in the cast-rolling zone has a better effect of refining the microstructure of the aluminum alloy sheets than the other complex fields, after adding the Al-Ti-B refiner whose content is 0.2%. |
