Papers by Author: Yu Bo Zuo

Abstract: On the basis of conventional hot-top casting, low frequency electromagnetic field was applied in the process of hot-top casting to produce 7050 aluminum alloy ingot, the influences of low frequency electromagnetic field on cold-shut have been studied. The experimental results show that under the effect of the low frequency electromagnetic filed, the depth of cold folding has been decreased, and the as-cast structure has been refined. The reasons for low frequency electromagnetic field improving the surface quality, refining the structure of the ingot were summarized.

Abstract: This paper discussed the effects of different cooling rate on the microstructure of the 4Y32 aluminum alloy and the refinement and modification on 4Y32 aluminum alloy by using Na and Al-10%Sr master alloys in various treatment states. And also the effect of Al-10Sr and Al-3Ti-1B compound modification on microstructures of 4Y32 aluminum alloy has also been studied. The results showed that: the primary silicon was eliminated during slow cooling. As the cooling rate increased, the number of primary silicon was also growing, but the size of primary silicon and eutectic silicon were significantly refined; when without modification, the shape of eutectic silicon was needle and flake; 4Y32 aluminum alloy could be effectively refined after Na modification, under the optimum addition amount of 0.8wt%. The best modification was achieved with 15 minutes, that is, the shape of primary silicon changed to small granular or oval and the primary silicon was eliminated; the as-cast structure has been improved after Al-10Sr modification, under the optimum addition amount of 0.2wt. %, the shape of eutectic silicon changed to fine short rod or point and the primary silicon was eliminated; However, in the compound modification, efficiency of Sr was decreased with the increasing additional amount of AI-3Ti-1B master alloy, which was attribute to the interaction of Sr and Ti.

Abstract: Low frequency electromagnetic casting is a new developed technology that appears in the recent years. In this paper, a comprehensive mathematical model has been developed to describe the interaction of the multiple physics fields during LFEC (low frequency electromagnetic casting) process. The model is based on a combination of the commercial finite element package ANSYS and the commercial finite volume package FLUENT, with the former for calculation of the electromagnetic field and the latter for calculation of the magnetic driven fluid flow, heat transfer and solidification. Moreover, the model has been verified against the temperature measurements obtained from one 7XXX aluminum alloy billet of 200mm in diameter, during the LFEC casting processes, respectively. There was a good agreement between the calculated results and the measured results. Further, the effects of electromagnetic frequency on fluid flow, temperature field and solidification during LFEC process have investigated numerically by using the mathematic model. The choosing criterion of the electromagnetic frequency during LFEC process has been used in order to obtain the best structure of the billets by analyzing the effects of fluid flow and temperature field on the solidification process in the presence of electromagnetic field.

Abstract: A comprehensive mathematical model has been developed to describe the interaction of the multiple physics fields during the conventional DC casting and LFEC (low frequency electromagnetic casting) process. The model is based on a combination of the commercial finite element package ANSYS and the commercial finite volume package FLUENT, with the former for the calculation of the electromagnetic field and the latter for the calculation of the magnetic driven fluid flow, heat transfer and solidification. Moreover, the model has been verified against the temperature measurements obtained from two 7XXX aluminum alloy billets of 200mm diameter, cast during the conventional DC casting and the LFEC casting processes. In addition, a measurement of the sump shape of the billets were carried out by using addition melting metal of Al-30%Cu alloy into the billets during casting process. There was a good agreement between the calculated results and the measured results. Further, comparison of the calculated results during the LFEC process with that during the conventional DC casting process indicated that velocity patterns, temperature profiles and the sump depth are strongly modified by the application of a low frequency electromagnetic field during the DC casting.