Purpose

The purpose of this paper is to reveal the solute segregation behavior in the molten and solidified regions during direct chill (DC) casting of a large-size magnesium alloy slab under no magnetic field (NMF), harmonic magnetic field (HMF), pulsed magnetic field (PMF) and two types of out-of-phase pulsed magnetic field (OPMF).

Design/methodology/approach

A 3-D multiphysical coupling mathematical model is used to evaluate the corresponding physical fields. The coupling issue is addressed using the method of separating step and result inheritance.

Findings

The results suggest that the solute deficiency tends to occur in the central part, while the solute-enriched area appears near the fillet in the molten and solidified regions. Applying magnetic field could greatly homogenize the solute field in the two-phase region. The variance of relative segregation level in the solidified cross-section under NMF is 38.1%, while it is 21.9%, 18.6%, 16.4% and 12.4% under OPMF2 (the current phase in the upper coil is ahead of the lower coil), HMF, PMF and OPMF1 (the current phase in the upper coil lags behind the lower coil), respectively, indicating that OPMF1 is more effective to reduce the macrosegregation level.

Originality/value

There are few reports on the solute segregation degree in rectangle slab under magnetic field, especially for magnesium alloy slab. This paper can act a reference to make clear the solute transport behavior and help reduce the macrosegregation level during DC casting.

中文翻译：

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预测不同磁场对大规格镁合金板坯直接冷硬铸造过程中溶质偏析的影响

目的

本文的目的是揭示在无磁场 (NMF)、谐波磁场 (HMF)、脉冲磁场下大尺寸镁合金板坯直接冷硬 (DC) 铸造过程中熔融区和凝固区的溶质偏析行为。磁场 (PMF) 和异相脉冲磁场 (OPMF) 两种类型。

设计/方法/途径

使用 3-D 多物理场耦合数学模型来评估相应的物理场。使用分离步骤和结果继承的方法解决耦合问题。

发现

结果表明，溶质缺乏倾向于出现在中心部分，而溶质富集区域出现在熔化区和凝固区的圆角附近。施加磁场可以极大地均匀化两相区的溶质场。NMF下凝固截面相对偏析水平的变化为38.1%，而OPMF2下为21.9%、18.6%、16.4%和12.4%（上线圈的电流相提前于下线圈）， HMF、PMF 和 OPMF1（上层线圈电流相位滞后于下层线圈），表明 OPMF1 对降低宏观偏析水平更有效。

原创性/价值

关于磁场作用下矩形板坯溶质偏析程度的报道很少，尤其是镁合金板坯。本文可为阐明溶质传输行为和帮助降低直流铸造过程中的宏观偏析水平提供参考。