Purpose

The purpose of this paper is to investigate the effect of pulsed magnetic field (PMF) with different duty cycles on the melt flow and heat transfer behaviors during direct-chill (DC) casting of large-size magnesium alloy billet and find the appropriate range of duty cycle.

Design/methodology/approach

A transient two-dimensional mathematical model coupled electromagnetic field, flow field and thermal field, is conducted to study the melt flow and temperature field under PMF and compared with that under the harmonic magnetic field.

Findings

The results reveal that melt vibration and fluctuation are generated due to the instantaneous impact of repeated thrust and pull effects of Lorentz force under PMF. The peak of Lorentz force decreases greatly with the increasing duty cycle, but the melt fluctuation region is expanded with higher duty cycle, which accelerates the interior melt velocity and reduces the temperature gradient at the liquid-solid interface. However, PMF with overly high duty cycle has adverse effect on the melt convection and limited influence on the interior melt. A duty cycle of 20% to 50% is a reasonable range.

Practical implications

This paper can provide guiding significance for the setting of duty cycle parameters on DC casting under PMF.

Originality/value

There are few reports on the effect of PMF parameters during DC casting with applying PMF, especially for duty cycle, a parameter unique to PMF. The findings will be helpful for applying the external field of PMF on DC casting.

中文翻译：

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大型镁合金坯在脉冲磁场下直接冷铸过程中流动和传热行为的数值研究

目的

本文的目的是研究不同占空比的脉冲磁场（PMF）对大型镁合金钢坯直接冷（DC）铸造过程中熔体流动和传热行为的影响，并找到合适的范围。占空比。

设计/方法/方法

建立了瞬态二维数学模型，将电磁场，流场和热场耦合，研究了PMF下的熔体流动和温度场，并将其与谐波磁场下的流动进行了比较。

发现

结果表明，在PMF下，洛伦兹力反复受到推力和拉力的瞬时影响会产生熔体振动和波动。洛伦兹力的峰值随占空比的增加而大大降低，但熔体起伏区域随占空比的增加而扩大，这将加速内部熔体速度并减小液-固界面处的温度梯度。但是，占空比过高的PMF对熔体对流有不利影响，而对内部熔体的影响有限。20％至50％的占空比是一个合理的范围。

实际影响

本文可为PMF下DC铸造的占空比参数的设置提供指导意义。

创意/价值

很少有关于使用PMF的直流铸造过程中PMF参数的影响的报道，特别是对于占空因数（PMF独有的参数）的影响。这些发现将有助于将PMF的外部领域应用于DC铸造。