Papers by Author: Jian Zhong Cui

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Authors: Ke Qin, Jian Zhong Cui
Abstract: A method for manufacturing composite ingot of 4045/3004/4045 aluminum alloy using direct-chill (DC) casting was introduced. The casting process, the temperature distribution near the composite interface and the macro- and microstructures were investigated. The results show that composite interface is well-bonded, planar and clean with little evidence of porosity, which belongs to a kind of metallurgical bonding. Also semi-solid layer with a certain thickness is formed under the effect of cooling plate, which can ensure the realization of casting process of composite ingot.
Authors: Jian Feng Zhang, Qi Xian Ba, Jian Zhong Cui
Abstract: The effect of DC gradient magnetic field and the sectional solidification on the structure of Al-Fe hypoeutectic alloy was investigated. The experiment results showed that the morphology and structure of the sample were homogenous, when it was bulk solidified without magnetic field. When the sample was sectionally solidified without magnetic field, the upper part had less iron content, bigger dendritic trunk and less interdendritic precipitate. When the sample was sectionally solidified in the gradient magnetic field, the above-mentioned differences between the upper and lower part were more prominent. The physical essence of the experiments was analyzed with quantum mechanics and solidification theory.
Authors: Song Lin Huang, Jian Zhong Cui
Abstract: Metallographic microscope is an indispensable tool for metallurgical studies, which played an important role in materials science research and experiment. For a long time, metallographic examination results are output in the form of a photosensitive film. This film-based imaging record way has become increasingly unsuited to the study of modern materials science. Digital metallographic microscope is a modern high-tech product, which combines optical microscopy techniques, photovoltaic technology and computer image processing technology. A digitization method is presented for the traditional metallographic microscope in this paper. Experimental results show that the digitization for metallographic microscope is feasible, which meets the requirements of modern materials science research.
Authors: Song Lin Huang, Jian Zhong Cui
Abstract: Different heating has an important influence on the efficiency of the production casting. Electromagnetic induction heating technology is a new heating technology. Metallic materials is heated itself directly through the Eddy current effect with the high-frequency electric heating principle. Because of its concentrated heat, high power density and high thermal efficiency, it has more superiority than the current conventional electric furnace heating technology. In this paper, the electromagnetic induction heating system has been designed, and this heating method is applied to the casting production. The results show that the electromagnetic induction heating is very suitable for casting production, which can greatly shorten the production time and improve productivity.
Authors: Song Lin Huang, Jian Zhong Cui
Abstract: Metallographic examination is one of the essential means of materials science research. Metallurgical polishing is a significant preparation before metallographic examination. In this paper, a polishing liquid automatic drip system was designed and related experiments were conducted. The results show that, as a secondary automation equipment of polishing process, polishing liquid automatically supply system can meet the requirements of metallurgical polishing, reduce the labor intensity, improve efficiency and also reduce the polishing liquid consumables waste. It also shows that automation and computerization in the field of material is not only feasible, but also essential for materials science research.
Authors: Jian Zhong Cui, Hai Tao Zhang, Yu Bo Zuo
Abstract: Hot tearing and cold cracks are major defects during direct chill (DC) casting of large sized ingots of high strength aluminium alloys. In order to solve these problems, based on a low frequency electromagnetic casting (LFEC) process, a new technology, electromagnetic casting with the application of an air blade (EMA) was developed. In the present work, this new technology was used to prepare large sized AA7055 aluminium alloy ingots and the effects of the low frequency electromagnetic field and the air blade on macro-physical fields, microstructure and cracking are studied by numerical and experimental methods. The results show that applying an electromagnetic field can modify the flow direction, increase the velocity of melt flow and homogenize the distribution of temperature in the sump. Applying an air blade can homogenize the distribution of temperature and decrease the stress and strain in the solidified ingot. Furthermore, the microstructure of the ingot is refined remarkably and cracking is eliminated by simultaneously applying the electromagnetic field and the air blade during DC casting.
Authors: Yu Bo Zuo, Lei Li, Qing Feng Zhu, Jian Zhong Cui
Abstract: In order to understand the effect of casting temperature on the low frequency electromagnetic casting process, 200mm billets of an Al-Zn-Mg-Cu alloy were produced, the microstructure was analyzed and the temperature field was measured during the casting process. The experimental results showed that low frequency electromagnetic casting process has an evident grain refining effect on aluminum alloy and casting temperature is not a sensitive parameter for this process, which can tolerate a large range of casting temperature. In the range of 710 to 750 °C, casting temperature does not show significant effect on the microstructure.
Authors: Hai Tao Zhang, Dong Tao Wang, Ke Qin, Xing Han, Bo Shao, Ke Sheng Zuo, Jian Zhong Cui
Abstract: The effect of phosphorus on primary silicon, phosphorus and mischmetal (Ce-50La) modification on primary and eutectic silicon and cooling rate on microstructure of Al-25%Si are investigated. The results show that, with the addition of phosphorus, the size of primary silicon decreases from 93.6μm to 24.75μm. The morphology of primary silicon changes from irregular to polygonal. When Al-25%Si is modified by phosphorus and mischmetal, primary and eutectic silicon all change effectively. Addition of mischmetal on the basis of phosphorus modification have no influence to primary silicon, but it can make morphology of eutectic silicon change from lamellar to short rod-like when the content of mischmetal reaches 0.5%. The cooling rate curves show the change of temperature in different height of wedge-shaped mould. When cooling rate increases, microstructure of Al-25%Si refines, the size of primary silicon decrease to 22.7μm. The results obtained from mechanical testing demonstrate that the addition of mischmetal and increasing of cooling rate increase hardness value of Al-25%Si alloy.
Authors: Bao Mian Li, Hai Tao Zhang, Jian Zhong Cui
Abstract: The effect of cooling rate and iron content on the solidification structures of copper-iron alloys had been investigated in this paper. The results show that the morphology of as-cast structure is mainly determined by iron content and the grain size is affected by both the iron content and cooling rate. The as-cast structure is obviously refined and its morphology changes gradually from columnar grains to equiaxed ones with the increase in iron content. When iron content is greater than 3% (in mass%) the as-cast structure is composed wholly of equiaxed grains. With the increase in cooling rate the as-cast structure is gradually refined and primary γ-Fe phase is gradually scattered uniformly throughout the matrix.
Authors: Chun Yan Ban, Dan Dan Jiang, Lian Liu, Jian Zhong Cui
Abstract: The effect of DC and AC magnetic fields on the macrostructure, morphology and distribution of the iron-containing intermetallics in the commercially pure Al was investigated. It is found that, at a cooling rate of 3°C/min, the grain is very coarse when the alloy solidifies both with and without magnetic fields. Comparing with the sample solidifies without magnetic field, the solidification structure has almost no change when it solidifies under DC magnetic field, while AC magnetic field changes the solidification structure obviously and makes grains show radial columnar crystals. The intermetallics is dominated by long needle-like phase when the sample solidifies under the condition of no magnetic field. Under AC magnetic field, the intermetallics is refined and accumulated towards the center of sample, and the amount of bone-like α-AlFeSi phase is increased remarkably. The mechanism of the effect of magnetic fields was discussed.
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