摘要
A secondary-cooling-segment electromagnetic stirring(S-EMS)experiment was performed at 150 A and 4 Hz to evaluate the effect of S-EMS on solidification characterization near the white band.The upper and lower parts of the white band exhibited average secondary dendritic arm spacing of 205.4 and 214.4μm,respectively.The S-EMS operation resulted in large Lorentz forces and cooling intensity,which could produce additional dendritic arms with low carbon concentrations,leading to local negative segregation.Moreover,a 3D flow-temperature-magnetic coupling numerical model was established.The results revealed that the magnetic induction intensity and Lorentz force were symmetrically distributed along rollers S1 and S2.The average velocity magnitude increased by approximately 42.52%,58.69%,and 64.11%for liquid fractions of 0.7,0.8,and 0.9,respectively.During the S-EMS operation,the Lorentz force may alter the velocity of the solidification front and promote the dissipation of superheat.Additionally,the influence of S-EMS on grain nucleation and growth was investigated using Gibbs free energy theory and component undercooling.Furthermore,a formation model for the white band was established,and the mechanism of white band formation was elucidated according to the changes in the solute-enriched layer,solute precipitation,and diffusion.
基金
supported by the National Natural Science Foundation of China(No.51774031)
the Project funded by China Postdoctoral Science Foundation(No.2023M730230).
作者简介
Corresponding author:Min Wang,wangmin@ustb.edu.cn。
