Simulation Of Uniaxial Solidification Process Of Billet Under Linear Electromagnetic Stirring

Electromagnetic stirring(EMS)is widely used in continuous casting process.It is a very effective solidification control technology which can improve the solidification structure quality of slab increase the nucleation rate in melt,promote the transformation of CET and reduce the macro-segregation.Through The study on electromagnetic field,temperature distribution and fluid flow during the alloy solidification process under electromagnetic stirring,we can obtain the best process parameters and mixing parameters.Electromagnetic stirring can refine the grains and improve the quality of slab with a properprocess parameters.In this paper,a laboratory self-designed single-side solidification device is taken as a physical model for continuous casting machine,and the Inconel 625 alloy is taken as the research object.The electromagnetic field and electromagnetic force distribution in melted alloy under linear electromagnetic stirring(L-EMS)is calculated by ANSYS software,then,the electromagnetic force,fluid flow,heat transfer and porous media modelare coupled to solve the solidification process of alloy in the slab.the influence of different parameters such as:current intensity,superheat,time of electromagnetic stirring and the position of linear electromagnetic stirrer on the flow and solidification process of alloy liquid are investigated.Further,the influence of electromagnetic stirring on the CET transformation is studied.It proves the feasibility of simulating the actual continuous casting process by the unilateral solidification device.The results of electromagnetic field tests and numerical simulation show that the magnetic induction intensity is larger at the end of the cooling copper plate,and can effectively penetrate the entire slab.The electromagnetic force is circumferential distribution around the center of the slab in the cross section of the slab center.In the slab,When the current intensity increases in a certain range,the magnetic induction and electromagnetic force at the same position increase correspondingly,while the magnetic induction at the same position decreases when the current frequency increases.Under linear electromagnetic stirring,the flow of the alloy liquid in the central cross section of the slab is swirling.With the increase of current intensity,the flow rate of the alloy liquid increases,the cooling rate increases,the solidification process of the slab accelerates,the shape of the solidified shell changes,the spacing of the secondary dendrite arm spacingdecrease,which shows that increasing the current intensity of the electromagnetic stirring further accelerate the solidification process.When the current density of linear electromagnetic stirring is 450 A,the maximum flow velocity on the central axis reaches 0.16 m/s,and the spacing of the secondary dendrite arm is calculated as smaller.It is recommended to use a linear electromagnetic stirrer to access the current intensity of 450 A.Under the condition of linear electromagnetic stirring,When the time of linear electromagnetic stirring increase to 90s,the deflection of the liquid core is more obvious.At the same position,the secondary dendrite arm spacing is the smallest at 0.03 m?0.08 m from the cooling copper plate.When the linear electromagnetic stirrer is located at EMS2,the alloy liquid flow in the cross section of the slab is swirling,and the velocity reach 0.25 m/s;The secondary dendrite arm spacing is smaller;and it is suggested that the linear electromagnetic stirrer should be placed at EMS2.Because the electromagnetic stirring to promote the superheat dissipation,the higher liquid fraction of superheat degree of 30?,at this condition,the center axis of the alloy rotational speed can reach 0.156 m/s,and the secondary dendrite arm spacing decreases.The results show that the self-made unilateral solidification device solidification calculation results agree well with the continuous casting process within the region of X direction 0.02 m?0.06 m,Y direction 0?0.04m and Z direction 0.02 m?0.12 m.And the following parameters for the unilateral solidification device experiment are proposed:current intensity as 450 A and electromagnetic stirrer placed at EMS2.