Numerical Simulated On Electromagnetic Stirring In Continuous Casting Of 26CrMoVTiB Round Billet

The element segregation is very serious at the inner and outer wall of the oil casing steel in a large steel mill.Under the sulfide and carbide corrosion atmosphere for a long time,the oil casing steel internal is easy to be corroded,and long term corrosion may cause the rupture of the oil casing and affect the normal production.As reasonable electromagnetic stirrer can reduce internal segregation of continuous casting billet of the oil casing steel,this thesis determines reasonable parameters of electromagnetic stirring by the numerical simulation analysis of E-EMS and F-EMS,which can reduce the C and Mo element internal segregation of the oil casing steel and improve the corrosion resistance of the oil casing steel.This thesis establishes 2D and 3D magnetic field and flow field mathematical mode of E-EMS and 3D magnetic field model of F-EMS by ANSYS software,and verifies the mathematical model with the field data.The influence of that the center line of E-EMS and the crystallizer copper tube is uneven on the magnetic induction intensity,the maximum electromagnetic force and flow field distribution of the liquid steel is analyzed.The distribution of maximum electromagnetic force and the best range of steel fluid velocity of the continuous casting liquid core of F-EMS are analyzed further,and the best parameters of E-EMS and F-EMS are determined.The magnetic induction intensity of the F-EMS is judged by white band way.Combining with the chemical analysis of internal composition of the oil casing steel continuous casting billet,the improvement of C,Mo segregation is identified.The experimental results are as follows:the error between the simulation value and the measured value of magnetic induction intensity of E-EMS is equal or less than 18Gs,inaccuracy deviation below 3 percent;the maximum error between the simulation value and the measured value of the magnetic induction intensity of F-EMS 12Gs,inaccuracy deviation below 2 percent.Therefore the precision of the electromagnetic stirring mathematics model is high enough to describe the field production.Through the numerical simulation analysis,it is founded that the electromagnetic force of the liquid steel near the side of the agitator in the crystallizer reaches the maximum when the frequency of the crystallizer agitator is 4Hz.The corresponding frequency value is related to the current intensity,the greater the current intensity is,the greater the frequency value corresponding to the maximum electromagnetic force is.The appropriate current intensity is 300 A,and the appropriate frequency is 3Hz or 4Hz by comprehensive analysis.The influence of core diameter on the frequency value corresponding the maximum electromagnetic force of the steel liquid is studied by numerical simulation.It is found that when the diameter of the liquid core changes from 70 mm to 50 mm,the frequency values decreases from 9Hz to 7Hz,and the change is very small.However the variation of core diameter has great influence on the maximum electromagnetic force under the same current intensity.Taking the liquid core diameter and flow of 26CrMoVTiB steel into account,the final current intensity and frequency should be selected at 600A,8Hz or 9Hz.Industrial test proves that under the optimized electromagnetic stirrer condition that the current intensity and frequency of the E-EMS are 300A and 4Hz,and the current intensity and frequency of the F-EMS are 600A and 9Hz,the C elements deviation decreases from 0.07%to 0.031%in the continuous casting billet,and the Mo elements deviation decreases from 0.08%to 0.038%.