| Magnesium alloy has been widely used because of its outstanding advantages such as lightweight,high specific strength,good thermoformability,good machinability,and good biocompatibility,and its advantages have been greatly highlighted in electronics,aerospace,biomedicine,and other fields.Centrifugal casting as one of the most commonly used special casting methods,has great advantages for forming pipe parts,so it has been widely studied.Electromagnetic centrifugal casting is the introduction of electromagnetic force based on centrifugal casting,to achieve the purpose of refining grains,and optimizing the structure and mechanical properties,which has become one of the directions of rapid development in recent years.Due to the complicated flow and force of metal liquid in the process of electromagnetic centrifugal casting,the high temperature and high pressure of a metal liquid,and the opacity of the mold,this paper adopts numerical simulation technology to conduct finite element numerical simulation technology on the process of centrifugal casting and electromagnetic centrifugal casting,to study the changes of the macroscopic physical field in the process of electromagnetic centrifugal casting and the influence of electromagnetic field on the microstructure before and after the introduction of the magnetic field.It provides new ideas for experiment and guides experiment at the same time.In this paper,AZ80 magnesium alloy was used as the experimental material and a finite element numerical simulation method was adopted to conduct numerical simulation on the process of centrifugal casting and electromagnetic centrifugal casting of magnesium alloy,aiming to explore the influence law of different variable conditions on the flow field,temperature field,pressure field and velocity field of the casting,and analyze the influence of centrifugal casting and electromagnetic centrifugal casting on the grain.The main research results are as follows:(1)For the analysis of the temperature field,under the conditions of pouring temperature at the entrance of 923.15 K,943.15 K,and 963.15 K,the casting solidified at the time of 16.4s,17.2s,and 18.2s respectively.At the position with the maximum temperature difference z = 0.03553 m,the inlet velocity of 0.45m/s is about 18.661 K higher than that of 0.4m/s,and the inlet velocity of 0.5m/s is about 13.048 K higher than that of 0.45m/s.The maximum temperature difference between 2100r/min and 2000r/min and 2050r/min is at Z = 0.03553,and the temperature difference reaches 20.385 K.When the magnetic field intensity is 0.05 T,the casting temperature increases by 32.1002 K,which has the greatest influence on the temperature;(2)As for the solidification field analysis,the liquid phase ratio at the pouring temperature of 963.15 K is 0.0272 higher than that at 943.15 K,0.0188 higher than that at923.15 K,and 0.0362 and 0.0446 higher after 11.4s,respectively.At the moment 4.4s,the liquid phase ratio was 0.8774,0.8599,and 0.8602,respectively,under the conditions of inlet pouring speed of 0.4m/s,0.45m/s,and 0.5m/s.When the rotation speed is 2000r/min,the liquid phase ratio is greater than that of 2050r/min and 2100r/min,but the liquid phase ratio is the same under the conditions of 2050r/min and 2100r/min.When the magnetic field intensity is 0.05 T,the liquid phase ratio at this point is 18% higher than that without the magnetic field;(3)For the force field,the pouring temperature at the entrance is about 140.91 Pa larger than 963.15 K and about 219.84 Pa larger than 923.15 K.The average pressure in the middle is 2743.58 Pa.Different inlet speeds have little influence on the casting pressure.After the casting is stabilized,the average pressure is 2763.16 Pa.At the moment 15.8s,the average pressure is 3021.54 Pa under the rotating speed of 2100r/min,2414.26 Pa under the rotating speed of 2050r/min,and 2324.17 Pa under the rotating speed of2000r/min.The magnetic field intensity has little influence on the wall pressure of casting,and the pressure fluctuates in the range of 2500 Pa to 3000Pa;(4)As for the velocity field analysis,the velocity field is not sensitive to the pouring temperature at the entrance,the pouring speed at the entrance,and the rotating speed,and the components of the velocity in the Y direction remain unchanged.The velocity with the magnetic field is about 0.047m/s lower than that without magnetic field;(5)As for the microstructure analysis,under the condition of electromagnetic centrifugal casting,the primary dendrite arm is subjected to less centrifugal force,and some secondary dendrite arms grow in the direction opposite to the centrifugal force,while the secondary dendrite arms grow in the side opposite to the centrifugal force,the length and density of the tertiary dendrite arms are higher than that of the electromagnetic centrifugal casting. |
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