Study On Control Technology Of Composite Field Homogenization Of Continuous Casting Aluminium Alloy Billet

2219 aluminum alloy belongs to heat treatable reinforced wrought aluminum alloy,has a higher specific strength,good welding performance and excellent high and low temperature mechanical properties,the working temperature can reach-250??300?,in the aerospace field has been widely used.But with the development of technology in aerospace and other fields,large aluminum alloy components are needed to meet the requirements.As the size of aluminum alloy ingot increases,the defects such as segregation,shrinkage porosity and cavity become more prominent due to the size effect,which greatly affects the use of ingot.In order to solve this problem,the Institute of Metal Engineering of Chinese Academy of Sciences proposed the forming technology of super-large size metal construction.Based on the concept of "base material construction,small size to large size",through the construction of small homogeneous casting billets as the basic element,through the subsequent surface treatment and diffusion bonding technology,the super-thick and large scale homogeneous forging billets were obtained.In this paper,the 2219 aluminum alloy with the section size of 200mm×1000mm was taken as the research object.Through numerical simulation analysis and solidification simulation experiment,the electromagnetic/ultrasonic composite field was studied.In this paper,numerical simulation software Fluent and Maxwell are used to simulate the electromagnetic casting process.It was found that the size of the paste area and the depth of the liquid pool increased significantly with the increase of the casting speed,and the corresponding relationship between the casting speed and the cooling water was explored.At the same time,the optimum cooling water distribution on the unit circumference of the length direction of the billet is 1:10:30 by simulation analysis.The simulation results of electromagnetic field show that the electromagnetic induction intensity is mainly concentrated on the surface of the billet and is the largest at the bending of the induction coil and the corner of the billet.The coupling analysis of electromagnetic field and flow field shows that electromagnetic field can significantly improve the distribution of flow field and temperature field in the liquid pool of casting billet,improve the size uniformity of paste zone at different positions,reduce the thick paste zone at the center of casting billet,and help to reduce the area that needs to be applied ultrasonic action.By adding ultrasonic in the solidification simulation experiment,the action rules of different ultrasonic application methods were explored.The results show that in the model studied in this paper,the area requiring ultrasonic action is the thick paste area in the center of the casting billet,and it is advisable to use higher ultrasonic power to expand the ultrasonic action range and obtain the homogenized grain refinement effect.At the same time,the grain refining effect is not sensitive to the time of ultrasonic application,so the casting speed can be appropriately increased to improve the production efficiency.In order to ensure the uniformity of grain size after refinement,the ultrasonic probe should not be inserted too deep into the paste area,and the best location is the top area of the paste area.