脉冲磁场对定向H13钢凝固组织的影响

Effect of Applied Pulsed Magnetic Field during Directional Solidification on Solidified Structure of H13 Steel

研究了脉冲磁场对不同抽拉速率条件下H13钢定向凝固组织的影响。结果表明:施加脉冲电压为50-200 V的脉冲磁场,可使H13钢的一次和二次枝晶间距减小,且其减小的程度随着脉冲电压升高而增加;随着脉冲磁场频率的提高,一次和二次枝晶间距呈现先减小后增加的趋势;随着抽拉速率的提高,枝晶间距减小的幅度降低。在定向凝固过程中,施加脉冲磁场使加热区的高温熔体向凝固前沿流动,提高了凝固前沿附近液相温度,从而使凝固前沿温度梯度升高,导致枝晶间距减小。

The effect of pulsed magnetic field（PMF） on the solidified structure of H13 steel during directional solidification with various growing rates was investigated. It was found that the primary dendrite arm spacing（λ1） and the secondary dendrite arm spacing（λ2） both decreased under the PMF with exciting voltages in a range of 50 V-200 V. λ1 and λ2 decreased with the increase of exciting voltage. With the increase of magnetic field frequency, λ1 and λ2 firstly decreased and then increased. While with the increase of growing rate, the reduction degree of λ1 and λ2 decreased. The PMF causes melt convection during directional solidification, which brings hot melt in the heating zone to the solidification front, thus the temperature gradient near the solidification front increases, leading to the decrease of λ1 and λ2.