Smart Liquid Processing R&D Department, Korea Institute of Industrial Technology, Incheon, 21999, Republic of Korea.
School of Mechanical Engineering, Korea University of Technology and Education, Cheonan, 31253, Republic of Korea.
Sci Rep. 2023 Feb 28;13(1):3382. doi: 10.1038/s41598-023-29522-y.
Grain refinement is a crucial issue in metallic materials. One of the emerging techniques to obtain equiaxed grains is to apply an electric current to the liquid metal during solidification. With this view, in this paper, the effect of electric current on the solidification behavior in various cavity shapes of mold was investigated. Cylinder-, cube-, and cuboid-shaped cavities designed to have similar cavity volume were used. By applying an electric current during the solidification of liquid aluminum, the grains were effectively refined with a grain size of approximately 350 µm for all three types of cavities. The circulating flow of liquid aluminum was observed to have a similar shear rate intensity in all three types of cavities, which is known to be sufficiently high (over hundreds of s) to induce dendrite fragmentation resulting newly generated nuclei. Dispersion of nuclei on unsolidified aluminum appeared differently according to the shape of the cavity, which influences final shape of refined zone. The area fraction of refined zone was affected by the relative relationship between the solidification completion time and the electric current application time. This study will provide insight to control of process parameters when electrically-assisted solidification is applied to a real product with a complex shape.
晶粒细化是金属材料中的一个关键问题。获得等轴晶的一种新兴技术是在凝固过程中向液态金属施加电流。基于这一观点，本文研究了电流对各种型腔形状的模具凝固行为的影响。设计了具有相似型腔体积的圆柱形、立方体和长方体型腔。通过在液态铝凝固过程中施加电流，有效地细化了晶粒，对于所有三种类型的型腔，晶粒尺寸约为 350μm。在所有三种类型的型腔中，都观察到液态铝的循环流动具有相似的剪切率强度，这被认为足以高（超过数百秒），从而诱导枝晶破碎产生新的晶核。未凝固铝上的晶核分布根据型腔的形状而不同，这会影响细化区的最终形状。细化区的面积分数受凝固完成时间和电流施加时间的相对关系的影响。本研究将为在具有复杂形状的实际产品中应用电辅助凝固时控制工艺参数提供参考。
