Numerical Simulation On Transient Temperature Field And Micro-structure In Electroslag Remelting And Validation

Electro-slag remelting(ESR) technology is a representative net shaping technology.It centralizes the metal refinement pure and the progressive solidification shaping,and it is a new method to produce roughcasts of machine parts with good quality and high strength. However, The mechanical property and durability property of the ingot lie on the solidification microstructure.Therefore,the accurate simulation of the microstructure can save the cost and improve the ESR process.In this paper,the solidification microstructure of ESR ingot was simulated by using the macro and micro dynamic coupling CAFE module in the ProCAST software.First of all,a two-dimensional geometric model of axisymmetric was stablished,and the transient temperature distribution in ingot was get with the macro coarse mesh (element) by finite element method. With the increasement of ESR ingot,the ESR reached steady state and the bath was close to the parabolic shape,its shape and size of the pool no longer changed.The microscopic temperature field was given by using the finite element shape functions interpolation.Because the mass transfer and energy fluctuations of solidification process is a random process,in this paper,a more realistic probability method (CA)was used to simulate the ESR steel microstructure.A nucleation model on a Gaussian distribution by Rappaz and KGT growth model by Kurz was taken to simulate the solidification process of ESR ingot.At the beginning of the ESR,the heat was transfered mainly by the bottom,so the columnar crystal growth along the vertical direction.With the increasement of the ingot,ingot solidification was influenced by thermal boundary conditions and internal temperature field,metal melting pond is increasingly close to parabolic shape,heat flux and the growth of columnar grain tend to the axial direction.Eventually a inverted V-shaped axial symmetry was formed.This paper also studied the relationship between ESR ingot temperature field and electrode melting rate and slag pool temperature and the variation of solidification structure with different nucleation parameters.To verify the accuracy of simulation results,this paper studied the cylindrical ingot remelted by the H13electrode materials which is cut by WEDM (Wire cut electric discharge machine)firstly, then grinded and finally etched with the Aqua regia about15minutes.The macrostructure of ESR ingot was consistent with the simulation.