Study On Pulse Current On Solidification Process Of Metal

The refinement of metal solidification structure has great significance for improving metal properties. As for the methods of controlling metal solidification structure refinement, the hot spot is the application of physical field. This article, using the method of experimental research, studies the law of the electric current pulse (ECP) to the metal solidification structure, and explores its mechanism.Focusing on Al-Si, Al-Cu and alloys, this article studies the influence of the pulse current peak value density and frequency on the macro and micro solidification structure. Through the research, it is found that the pulse current has great refinement to the solidification macrostructure of Al-Si and Al-Cu. With the increase of the pulse current peak value density and frequency, the grain size of its macrostructure is decreasing gradually. The pulse current density and frequency also have great influence on the solidification microstructure. With the increase of the parameter of ECP, for the dendritic crystals of the primary a-A1 phase, its axial size is becoming small, and into the shape of globe. The second-arm is shorter, and gradually disappears. Also the research has found that with the increase of the parameter of ECP, the primary a-Al phase is gradually well-distributed.For the microstructure of Al-Si alloy, also it is found that eutectic Si phase is changed short strip and well-proportioned distribution with ECP from long strip without ECP.During the comparative experiment of pure Al, pure Cu, and Al-Si, Al-Cu alloys, it is found that different metal, under the same parameter of ECP, has different refinement effect to grains. As for the alloys of different solute concentration, with the increase of Cu content of hypoeutectic Al-Cu alloys, the refinement effect of ECP on macrostructure is weakened. In addition, it is illustrated farther that there is a closely relationship between effect of ECP on solidification structure and characteristics of metal.This article explores the refinement effect of the pulse current peak value density, frequency and pulse width on solidification structure of metal. And it is found that the effect is proportional to the square of the peak value density, and to the root square of frequency and pulse width. It shows that the effect of peak value density is larger than that of the frequency and pulse width.