Study On Solidification Of Low Melting Point Liquid Metal With Bottom Argon Blowing During Ingot Casting

In this paper,the influence of argon blowing process on the casting solidification of ingot is studied by means of solidification experiment and mathematical simulation.The influences of the arrangement of one or double gas porous beams and different bottom blowing argon flow rates on the flow field,temperature field and solidification structure of ingot in the casting process were investigated,and the mathematical simulation of the flow field and temperature field in the casting process was carried out.Through solidification experiment,the results show that the temperature difference of monitoring points in the vertical direction decreases with the increase of bottom blowing argon flow,and the temperature of each monitoring point has obvious fluctuations before solidification of the alloy liquid,and all monitoring points solidify almost at the same time.In the casting process,bottom blowing argon significantly delayed the initial solidification time of the lower part of the model,decreased the temperature drop rate at the bottom of the model at the later casting stage,and increased the temperature drop rate at the center of the ingot mould in casting process to promote the simultaneous solidification of the alloy liquid in the ingot mold.Argon blowing at the bottom of the double permeable brick under different wall cooling conditions can effectively refine the solidified structure of the ingot.When the bottom blowing argon of the single gas porous beams at the bottom of the mold is carried out,the bottom blowing argon quantity is small,and the effect on the temperature field in the mold is better.When the bottom blowing argon quantity is 150mL/min,the argon bubble rises faster,and the stirring effect on the lower part of the model is poor,and the metal solidification at the bottom of the model is faster.In the process of mathematical simulation,combining with the solidification test,the mathematical simulation of the temperature change in the ingot mold under the condition of bottomless argon blowing and the bottom argon blowing of double gas porous beams was verified.And the flow field,temperature field,bubble motion state and solidification process in the casting process were simulated.By comparing the temperature change curves of the monitoring points in the mold during the casting process between the experiment and the numerical simulation,it is found that the results of the numerical simulation and the solidification experiment are in good agreement.When casting under the condition of bottomless argon blowing,the flow velocity of the fluid in the mold is small,the flow velocity in the bottom area of the model is poor,and the flow velocity in the corner area is almost zero.The bottom blowing argon is carried out during casting,and the stirring effect of argon bubble promotes the liquid flow in the mold,increases the flow rate of the fluid,and improves the fluidity of the bottom and corner area of the model.When casting under the condition of bottom argon blowing,the argon bubble deviates to both sides of the upwelling strand and moves upward with the upwelling strand during the rising process.With the increase of the amount of bottom blowing argon,the rising velocity of argon bubble increases obviously,but the dispersion range of argon bubble decreases obviously.The variation of the temperature field in the mold during the casting process shows that the change of the isotherm in the mold is advanced from the wall to the center in the horizontal direction and upward in the vertical direction from the bottom of the mold.In bottomless argon blowing casting,the isotherm in the mold changes from "V" shape to "U"shape,while in bottom argon blowing casting,the stirring effect of bottom-blowing argon homogenized the temperature in the mold,and improved the horizontal and vertical temperature gradient in the mold.The ingot solidifies from the bottom corner of the model,horizontally from all sides to the center,and vertically from bottom to top.In the process of casting,argon blowing at the bottom of the mold significantly lengthens the beginning solidification time at the bottom corner of the mold,accelerates the solidification speed of the solidification shell in the vertical direction,and is beneficial to the sequential solidification of the ingot and improves the quality of the ingot.