Research On The Influence Of Combined Electromagnetic Stirring On Negative Segregation Of Small Square Billet In Continuous Castin

Continuous casting electromagnetic stirring helps to improve the quality of the slab,but when the electromagnetic stirring intensity exceeds a certain critical value,negative segregation will occur in the slab,and this negative segregation zone may affect the hardenability,surface hardness and mechanical properties of steel products.Performance is adversely affected.Therefore,this study takes a steel mill billet 30Cr13 as a sample,simulates and calculates the temperature field,flow field and typical element solute distribution characteristics in the billet molten steel;The effect of segregation.According to the simulation results to guide industrial experiments,explore the influence of the combination of electromagnetic stirring in the crystallizer and electromagnetic stirring at the end of solidification on negative segregation.Key findings of the study include:(1)The simulation research on the influence of combined electromagnetic stirring on the negative segregation of the billet shows that: as the electromagnetic stirring current of the mold increases from 100 A to 300 A,the subcutaneous negative segregation of the billet is improved;When the current continued to increase to 500 A,the degree of negative segregation of the slab increased correspondingly,and the mass percentage of solute decreased from0.6928% to 0.6903%.The mass percentage of solute in the subcutaneous area of the billet decreased from 0.6928 % to 0.6905 %,so the optimal electromagnetic stirring parameter of the crystallizer was 3 Hz+300 A.On this basis,the negative segregation of the slab was found to be simulated and calculated with different combinations of electromagnetic stirring parameters at the end of solidification,and it was found that a negative segregation area would be formed near the central area of the slab,and the degree of negative segregation would decrease as the power increased.(2)Experimental research on the influence of different solidification terminal currents on slab segregation under combined electromagnetic stirring shows that: when the frequency of terminal electromagnetic stirring is 5 Hz,the effects of terminal electromagnetic stirring currents of 450 A,500 A and 550 A on slab segregation are investigated.Influenced by carbon segregation,when the terminal electromagnetic stirring current is 550 A,the carbon segregation index of the slab section is 0.92-1.02.Under this condition,the carbon segregation of the slab is best controlled,and it is more conducive to the uniform distribution of carbon elements in the slab.(3)Experimental research on the effect of different superheating degrees on slab segregation under combined electromagnetic stirring parameters shows that: the higher the superheating degree of molten steel,the more serious the slab segregation;the lower the superheating degree,the better the segregation control.When the degree of superheat is 20 ℃,the distribution of carbon element in the slab is the best,the carbon segregation index is0.92-1.06,and the central segregation rating is 0.5.(4)The experimental research on the influence of different solidification end parameters on the shrinkage cavity and equiaxed crystal ratio of the slab under combined electromagnetic stirring shows that the electromagnetic stirring at the solidification end has a certain improvement effect on the shrinkage cavity of the slab.,the areal equiaxed crystallization ratio and radial equiaxed crystallization ratio both show an upward trend;when the terminal electromagnetic stirring frequency is 5 Hz,the current increases to 550 A,and the area equiaxed crystallization ratio and radial equiaxed crystallization ratio have the best control effect,reaching 37.5 % and 61.25 % respectively.