摘要
The application of electric current pulse（ECP） to a solidification process refers to the immersion of electrodes into the liquid metal and the employment of thermal insulators on the upper surface of metal.In order to ascertain the effects of these two factors on the structure refinement by the ECP technique,three groups of experiments were performed with different types of electrodes or various thermal insulators.By the comparison between solidification structures under different conditions,it is followed that the electrode and the thermal insulator have an obvious influence on the grain refinement under an applied ECP,and further analysis demonstrates that the thermal conditions of the liquid surface play a vital role in the modification of solidification structure.Also,the results support the viewpoint that most of the equiaxed grains originate from the liquid surface subjected to an ECP.
在实际的铸造过程中应用脉冲电流要求电极插入熔体中并在熔体的上面覆盖保温剂。为了探明这两个因素对脉冲电流细化组织的影响,采用不同电极或不同保温剂进行了3组实验。通过比较不同条件下得到的凝固组织,发现在脉冲电流作用下电极和保温剂都对凝固组织的细化有明显的影响。进一步的分析表明,液面在凝固组织的细化中起到了关键性的作用,而且结果也支持了在脉冲电流作用下等轴晶主要来自液面的观点。
基金
Project(2009AA03Z110) supported by the National High Technology Research and Development Program of China
Project (2011CB012902) supported by the National Basic Research Program of China
