Simulation of heat transfer and microstructure during solidification of φ800 mm large section continuous casting round billet
Taking 42CrMo4 round billet with a section size of φ800 mm as the research object,a large round billet model was established with ProCAST finite element method and CAFE method.The effects of superheat,drawing speed and specific water volume in secondary cooling zone on solidification behavior and grain structure were com-pared.The results show that the influence of the drawing speed on the solidification temperature,solidification end point and the thickness of the solidified billet is greater,while the influence of superheat on the grain growth is grea-ter.When the drawing speed is increased by 0.02 m/min,the solidification end point moves back about 3 m,and the change of superheat and specific water volume in the secondary cooling zone has no obvious effect on the temper-ature and central solid fraction.When the superheat is increased from 10 ℃ to 55 ℃,the equiaxial crystal rate de-creases from 43.2％to 9.2％,while the influence of pulling speed and secondary cooling zone specific water volume on the equiaxial crystal rate is not obvious,and the change is less than 8％.Based on the electromagnetic stirring position of the end,an optimization scheme was proposed for the existing process.The superheat was reduced to 10 ℃,the specific water volume was reduced to 0.16 L/kg,which could effectively improve the equiaxed crystal rate and refine the grains.
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