Numerical Simulation Study Of Electromagnetic Stirring In The Second Cold Zone Of Continuous Casting Of Extra Thick Slab

With the rapid development of marine engineering,new requirements are constantly put forward for the quality of steel used in marine engineering equipment.Among them,the large size and high strength of slabs are the key research and development goals of marine engineering steel.Therefore,the process technology for producing extra-thick slabs has developed rapidly in recent years.In order to reduce the center segregation of extra-thick plate continuous casting billet and improve the equiaxed crystal ratio,electromagnetic stirring technology is applied to the continuous casting production process.Among them,the electromagnetic stirring technology in the secondary cooling zone in the extra-thick plate continuous casting production process is the key to reducing the center segregation of the slab and improving the equiaxed crystal rate.It is necessary to apply electromagnetic stirring to the secondary cooling zone in the extra-thick plate continuous casting production process.The macroscopic transport and solidification behavior within the cast slab were systematically studied.Therefore,this paper analyzes the magnetic field distribution of the center cross-section of different electromagnetic stirrers by numerical simulation,studies the distribution of magnetic induction intensity,electromagnetic force and current density under different coil energization currents and frequencies,and discusses the distribution of slab flow field and temperature field under electromagnetic stirring in the secondary cooling zone.The important conclusions are as follows:(1)The magnetic induction intensity and electromagnetic force increase with the increase of the energizing current;The magnetic induction intensity of the center point of the cross-section of the electromagnetic stirrer decreases with the increase of frequency.The current density of the cross-sectional center point of the electromagnetic stirrer increases with the increase of frequency;With the increase of frequency,the electromagnetic force first increases and then decreases,and the electromagnetic force reaches a maximum when the frequency is 4Hz.(2)With the increase of the slab pulling speed,the thickness of the solidified billet shell decreases;The slab pulling speed was from 0.5 m/min to 0.7 m/min,the thickness of the solidified billet shell was reduced by 15 mm at a distance of 2.8 m from the meniscus.(3)When the stirring method is the same,the stirring speed of the molten steel will increase with the increase of the slab pulling speed;The slab pulling speed was from 0.5 m/min to 0.7 m/min,the average flow rate of molten steel in double-ring,double-disc and three-ring stirring increases by 0.01m/s,0.009m/s and 0.005m/s,respectively.(4)For every 50 A increase in current intensity,the average flow rate of molten steel in double-ring,double-disc and three-ring stirring increases by 0.12m/s,0.085m/s and 0.09m/s,respectively,which is a linear increase.(5)As the slab pulling speed increases,the temperature of the molten steel decreases more slowly.When the distance between the mixing rollers is 40°,the double disc type stirring has the best effect;When the mixing roller distance is 30°,the threering stirring works best.Both the two-disc and tricycle stirring have the most uniform temperature distribution at a current of 200 A.