Multiphase Solidification Modeling of Solidification Structure Evolution and Macrosegregation of Round Bloom Continuous Casting Process with Mold Electromagnetic Stirring and Final Electromagnetic Stirring

Abstract

Base on Eulerian‐Eulerian method, a 2D/3D mixed columnar‐equiaxed solidification mathematical model, which takes into consideration the macroscale heat transfer and fluid turbulent flow with microscale grains nucleation and crystal growth, was developed to predict the solidification structure evolution and macrosegregation in continuously cast round bloom. The results show that the M‐EMS could accelerate superheat dissipation and promote grain nucleation in mold, but the horizontal swirl induce by M‐EMS has a strong washing effect on the solidification front and leads to subsurface negative segregation. When the M‐EMS current intensity increases from 200 to 300A, the subsurface negative segregation ratio decreases from 0.935 to 0.875. The F‐EMS would improve the center segregation, but also lead to the formation of negative segregation zone near the round bloom center due to the enhancement of solute washing induced by F‐EMS. As the F‐EMS current intensity increases from 150 to 300A, the center segregation ratio decreases from 1.148 to 1.075, and the negative segregation ratio near the round bloom center decreases from 0.985 to 0.977. Another phenomenon is found that the nucleation of equiaxed grain ahead of columnar tips restrains the solute diffusion in the liquid phase and leads to a local macrosegregation in CET zone.This article is protected by copyright. All rights reserved.

Optimization of Process Parameters for 40Cr Steel Continuous Casting Round Bloom with Pulsed Magneto‐Oscillation Treatment

“…Phenomena such as remelting and dissociation occurred near the solidification front, leading to a noticeable refinement of primary dendrites and accelerating the diffusion of solutes enriched in interdendritic spaces. [6] Zhao et al [42] found that the solidification structure of metal was improved with the increase in pulse peak current, but excessive peak currents could induce the Joule heating effect, potentially remelting the grains. [43] Therefore, despite the increase in temperature drop and flow effects with the rise in current, it is essential to prevent excessive Joule heating effects and control energy consumption.…”

“…Due to solute redistribution and forced cooling, the heterogeneous defects, such as macrosegregation and shrinkage cavity, are inevitable in continuous casting and are difficult to eliminate through subsequent processes, which seriously affect the quality of steel products. [1,2] Hence, a variety of technologies have been developed to improve the homogeneity of casting blooms, such as electromagnetic swirling flow, [3,4] electromagnetic stirring, [5][6][7] soft or heavy reduction, [8][9][10][11] and so on. The pulsed electromagnetic field, with advantages such as low energy consumption, convenient application, and significant effects, has become a research hotspot in the field of solidification structure refinement technology.…”