Papers by Author: Xiang Hua Liu

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Authors: Hai Bo Xie, Zheng Yi Jiang, Dong Bin Wei, Xiang Hua Liu, Guo Dong Wang
Abstract: Rolling temperature is an important factor affecting mechanical properties of hot rolled strip significantly. Traditional techniques cannot meet higher precision control imperatives. In the present work, a novel knowledge-based system has been developed for the temperature prediction in hot strip mills. Neural network has been used for this purpose, which is an intelligent technique that can solve nonlinear problem of temperature control by learning from the samples. Furthermore, an annealing robust learning algorithm was presented to adjust the hidden node parameters as well as the weights of the adaptive neural networks. Simulations in a multi-object mode have been carried out to verify the effectivity of new neural optimization system. Calculation results confirm the feasibility of this approach and show a good agreement with experimental values obtained from a steel plant.
Authors: Jian Zhong Xu, Hong Shuang Di, Dian Yao Gong, Xiang Hua Liu, Guo Dong Wang, Xiao Lin Zhao
Authors: Xiao Ming Zhang, Zheng Yi Jiang, Hei Jie Li, Z. Fan, Xiang Hua Liu, Guo Dong Wang
Abstract: In twin-roll strip casting process, the temperature variation of casting roll can result in roll thermal stress and fatigue. It not only affects the thermal deformation of casting roll and the generation of the roll surface cracks significantly, but also influences the surface quality, shape and profile of the produced strip, and the service life of the casting roll. In this paper, a 3D coupling thermal-flow finite element modelling has been conducted. For twin-roll casting of stainless steel, the influences of the casting speed and liquid level in molten pool on the temperature field of casting roll have been simulated and discussed. The developed model is very helpful in optimising the processing parameters and the design of casting roll during twin-roll thin strip casting.
Authors: Li Cui, Xian Lei Hu, Xiang Hua Liu
Abstract: In order to analysis the effect of leveling strategy on the quality of plate products, the curvature integration by elastic-plastic differences was adopted to simulate leveling results by different leveling strategy. It had studied plastic deformation ratio, residual stress, residual curvature and leveling force for different leveling strategies to find the effectual strategy and the adaptability conditions were given. Additionally, static pressure leveling with the time delay strategy was analyzed, which was proved to be an effectual strategy to resolve the leveling problem for high strength thicker plate by a certain 3500mm mill plate.
Authors: Zong An Luo, Guo Dong Wang, Xiang Hua Liu, Jian Ping Li, Li Jun Wang, Fu An Hua
Abstract: In order to meet the demand of steelmakers, series of experimental facilities such as thermo-mechanical simulator, pilot hot rolling mills, controlled cooling system, pilot cold rolling mills, simulator for continuous annealing of strips, and hot-dip galvanizing simulator have been developed and applied by the RAL. These instruments can be used to simulate different processing technologies of steel forming which include continuous casting, hot rolling, controlled cooling, cold rolling, annealing and surface treatment(such as coating), etc. They provide unique research means for the R&D activities of China’s iron and steel industries. The characteristics, experimental functions, performance parameters and application of these facilities are introduced in the paper.
Authors: Hua Ding, L. Li, Y.Z. Xiao, Xiang Hua Liu, Guo Dong Wang, S.E. Hu, Wei Hua Sun
Authors: S.J. Yao, Lin Xiu Du, Xiang Hua Liu, Guo Dong Wang
Abstract: Generally, three typical behaviors are recognized in hot-deformation of austenite. However, considering that those austenite grains involved in single-pass deformation are mostly on the scale of dozens of micrometers or even much larger than that, it is meaningful to investigate hot-deformation behaviors of austenite grains smaller than 10μm. In the current paper, austenite grains of different sizes were prepared through repetitive treatment of rapid reheating and quenching with changing the holding temperature and/or holding time. Kinds of true stress-true strain curves at 900oC and 950oC indicate that austenitic deformation can be gradually coordinated by grain boundary behaviors, such as grain boundary sliding and/or diffusion. Simultaneously, the macroscopic deformation is more likely to be dominated through co-operation grain boundary sliding (CGBS).
Authors: Hong Bo Yang, Fu Xian Zhu, Xiang Hua Liu, Kuai She Wang
Abstract: Cementite spheroidization of GCr15 bearing steel includes granulating and growth of cementite. The effects of divorced eutectoid transformation (DET) temperatures on growth of cementite were studied. It was found that the particles of cementite are fine and uniform when DET occurs at 690~720°С, and alloy elements mostly precipitate at different temperatures during cementite growth of GCr15 bearing steel; Cr and Si mostly precipitate in the eutectoid temperature upper limit, while Mn is in the eutectoid temperature lower limit.
Authors: Xin Liu, Lei Su, Xiang Hua Liu
Abstract: The key technology of direct rolling of free heating for bar and rod mill (DROF) was briefly introduced. Compared with the traditional process, the DROF can reduce energy consumption and emission, so as to decrease the production cost. It is very important to understand temperature field of continuous casting billet (CC-billet) to carry out the research on DROF technology. In order to reduce the loss of heat, the insulation cover is used, so it can effectively reduce the roll force and motor power. The rolling parameters, such as roll force and power, in former 4 stands of roughing mills were investigated by finite element method (FEM). The results show that the average temperature of the CC-billet after 300s from the cutting time can still be over 970°C, it can meet the need of direct rolling.
Authors: Zhang Ying Liu, Xiang Hua Liu, Guo Dong Wang
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