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Research methods and influencing factors of interfacial heat transfer during sub-rapid solidification process of Strip casting

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Journal of Iron and Steel Research(International) 2022年第1期29卷 3-16页

作者： Wan-lin Wang Cheng Lu Le-jun Zhou Pei-sheng Lyu School of Metallurgy and Environment Central South UniversityChangsha 410083HunanChina National Center for International Research of Clean Metallurgy Central South UniversityChangsha 410083HunanChina

Interfacial heat transfer behavior between the molten steel and twin-rolls is a key issue in the Strip casting process,and it has already attracted wide attention from industrial and academic communities of steel.The research methods and influencing factors on the interfacial heat transfer were summarized.Numerical simulation models,semi-industrial scale,and laboratory equipment have been developed in this field,and these methods were also improved by worldwide researchers based on the development of computer,automatic,and visual technologies.Coating properties,naturally deposited film,and casting parameters are the main factors which affect the heat transfer significantly.Although lots of research has been carried out,the internal relations among these influencing factors,interfacial heat transfer,and the quality of the strip are still worth to be further explored.Keywords Strip casting Interfacial heat transfer Simulation method Coating property Naturally deposited film casting parameter.

关键词： Strip casting Interfacial heat transfer Simulation method Coating property Naturally deposited film casting parameter

Effect of phosphorus content on interfacial heat transfer and film deposition behavior during the high-temperature simulation of Strip casting

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International Journal of Minerals,Metallurgy and Materials 2024年第5期31卷 1016-1025页

作者： Wanlin Wang Cheng Lu Liang Hao Jie Zeng Lejun Zhou Xinyuan Liu Xia Li Chenyang Zhu School of Metallurgy and Environment Central South UniversityChangsha 410083China National Center for International Research of Clean Metallurgy Central South UniversityChangsha 410083China Institute of Research of Iron and Steel ShasteelJiangsu ProvinceZhangjiagang 215625China

The interfacial wettability and heat transfer behavior are crucial in the Strip casting of high phosphorus-containing steel.A hightemperature simulation of Strip casting was conducted using the droplet solidification technique with the aims to reveal the effects of phosphorus content on interfacial wettability,deposited film,and interfacial heat transfer behavior.Results showed that when the phosphorus content increased from 0.014wt%to 0.406wt%,the mushy zone enlarged,the complete solidification temperature delayed from1518.3 to 1459.4℃,the final contact angle decreased from 118.4°to 102.8°,indicating improved interfacial contact,and the maximum heat flux increased from 6.9 to 9.2 MW/m2.Increasing the phosphorus content from 0.081wt%to 0.406wt%also accelerated the film deposition rate from 1.57 to 1.73μm per test,resulting in a thickened naturally deposited film with increased thermal resistance that advanced the transition point of heat transfer from the fifth experiment to the third experiment.

关键词： Strip casting interfacial heat transfer interfacial wettability naturally deposited film phosphorus content

Characterization of Microstructure and Texture in Grain-Oriented High Silicon Steel by Strip casting

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Acta Metallurgica Sinica(English Letters) 2015年第11期28卷 1394-1402页

作者： Xiang Lu Yun-Bo Xu Feng Fang Yuan-Xiang Zhang Yang Wang Hai-Tao Jiao R.D.K.Misra Guang-Ming Cao Cheng-Gang Li Guo-Dong Wang State Key Laboratory of Rolling and Automation Northeastern University Laboratory for Excellence in Advanced Steel Research Department of MetallurgicalMaterials and Biomedical EngineeringUniversity of Texas at El Paso

Grain-oriented 4.5 wt% Si and 6.5 wt% Si steels were produced by Strip casting, warm rolling, cold rolling, primary annealing, and secondary annealing. Goss grains were sufficiently developed and covered the entire surface of the secondary recrystallized sheets. The microstructure and texture was characterized by OM, EBSD, TEM, and XRD. It was observed that after rolling at 700 ℃, the 6.5 wt% Si steel exhibited a considerable degree of shear bands, whereas the 4.5 wt% Si steel indicated their rare presence. After primary annealing, completely equiaxed grains showing strong y-fiber texture were presented in both alloys. By comparison, the 6.5 wt% Si steel showed smaller grain size and few favorable Goss grains. Additionally, a higher density of fine precipitates were exhibited in the 6.5 wt% Si steel, leading to a ~ 30-s delay in primary recrystallization. During secondary annealing, abnormal grain growth of the 6.5 wt% Si steel occurred at higher temperature compared to the 4.5 wt% Si steel, and the final grain size of the 6.5 wt% Si steel was greater. The magnetic induction B8 of the 4.5 wt% Si and the 6.5 wt% Si steels was 1.75 and 1.76 T, respectively, and the high- frequency core losses were significantly improved in comparison with the non-oriented high silicon steel.

关键词： Strip casting Grain-oriented high silicon steel Microstructure Texture

Measurement and AFPS control of molten steel level in Strip casting

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Journal of University of Science and Technology Beijing 2005年第1期12卷 16-22页

作者： LiyeZhu TihuaWu YuanFang DepartmentofAutomation ShanghaiJiaotongUniversityShanghai200030China BaosteelTechnologyCenter Shanghai201900China

The measurement and control of the molten steel level are studied, which affect the quality of strip surface in Strip casting. A system of molten steel measurement with a CCD (Charge Coupled Devices) sensor is designed, real-time measured data are given and its precision is analyzed. The level fluctuation model is derived, and an adaptive fuzzy-PID controller with supervisory control (AFPS) is proposed. The stability of the system is proved using Lyapunov theorem, and the simulation results are given when the model, the casting speed and the roll gap change. It is suggested that this kind of coupled nonlinear and time varying system is stable and robust using the designed AFPS controller.

关键词： Strip casting molten steel level CCD adaptive fuzzy-PID supervisory controller

Microstructure of NdFeB Strip casting Flake

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Journal of Iron and Steel Research(International) 2005年第3期12卷 60-62页

作者： LIBo GUOBing-lin WANGDong-ling LIUTao LIUWen-chang YUXiao-jun CentralIronandSteelResearchInstitute Beijing100081China

The microstructures of NdFeB conventional ingot and Strip casting (SC) flake were studied by BSE and energy spectra. The non-equilibrium state of the microstructure of SC flakes was discussed. By observing the change of microstructure of SC flakes after annealing at 700 ℃, 800 ℃ and 900 ℃, the characteristics of SC flakes were investigated further. The influence of the characteristic on magnetic property was analyzed.

关键词： microstructure NdFeB magnet Strip casting annealing

Simulation of meniscus fluctuations in the feeding system used in Strip casting

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Baosteel Technical Research 2017年第3期11卷 1-6页

作者： REN Sanbing FAN Junfei Research Institute Baoshan Iron & Steel Co. Ltd. Shanghai 201900 China

The feeding system used in the Strip casting process delivers molten metal from the tundish to the pool that is bordered by side dams and rolls and is one of the key units in the production of high quality strip metal. The traditional method for studying this key unit is to use a combination of a water model and a mathematical model. However,the relations in the model with and without roll rotation have not been clearly revealed in previous studies. A 2D transient model based on a continuity equation, momentum equation, turbulent equations, and a VOF equation was established in this study and used to simulate the meniscus fluctuation. A half model with a structured grid was used for the reported simulation. The simulation showed that significant differences existed in the fluctuation in the flow fields and wave length with or without the roll rotation. The wave fluctuation exhibited uncertainty and an unstable character in the roll rotation condition. The level fluctuation employing different process parameters such as rotating speed and immersion depth of tip angle was simulated and compared with and without roll rotation. The study results showed that the meniscus fluctuation of twin-roll Strip casting was primarily affected by the roll rotation, and the level fluctuation increased with the increase in rotation velocity and decreased with immersion depth.

关键词： Strip casting mathematical simulation meniscus level fluctuation

Microstructural Characterization of Novel Ni-Containing Nd-Fe-B strips by Strip casting

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Journal of Rare Earths 2006年第1期24卷 85-88页

作者：李成栋朱学新石力开 National Engineering Research Center for Non- Ferrous Metal Composites General Research Institute for Non- Ferrous Metals Beijing 100088 China

The characteristics of novel Nd-Fe （Ni, Co, Al ）-B microstructure prepared by Strip casting technique were studied. The novel microstructure was observed using scanning electron microscope （SEM） and transmission electron microscope （TEM）. Along the direction of heat flow, there are two kinds of different microstructures. Close to the wheel side, there is a thick layer containing many polygonal Nd2Fe14B grains. Near the free surface side, however, there are relative uniform platelike Nd2Fe14B grains whose growth direction is not completely the direction of the heat flow during solidification. The formation of the novel microstructure is presumed to be the contribution of the special temperature field and Ni component.

关键词： Nd-Fe （Ni, Co, Al）-B Strip casting columnar crystals novel microstructure rare earths

Effects of Strip casting and Annealing on Electrochemical Properties of LPCNi_(3.55)Co_(0.75)Mn_(0.4)Al_(0.3) Hydrogen Storage Alloys

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Journal of Rare Earths 2004年第2期22卷 254-258页

作者：吴朝玲陈云贵李锋陶明大涂铭旌唐定骧 Department of Metallic Materials Sichuan University Chengdu 610065 China

The effect of thickness (1 similar to 10 mm) of the ingots on the electrochemical properties of as-cast and annealed strip cast LPCNi3.55Co0.75Mn0.4Al0.3 hydrogen storage alloys was investigated. It is found that the 0.2 C discharge capacity of as-cast LPCNi3.55Co0.75Mn0.4Al0.3 alloy increases with the increase of the thickness of the ingots. As-east alloy with the thickness of 10 mm shows better activation property, higher 1C discharge capacity and better cyclic stability than others. It is mainly contributed to its larger unit cell volume and less internal stress. Annealed LPCNi3.55Co0.75Mn0.4Al0.3 alloy with the thickness of 3 mm shows much better comprehensive electrochemical properties than as-east one; The cyclic. stability of the alloy with the thickness of 6 mm and the activation properties of the alloys with the thickness of 3 similar to 6 mm are improved after annealing. It is mainly owing to the great release of internal stress and the decrease of the segregation of Mn in the alloys.

关键词： energy materials Strip casting annealing electrochemical property AB(5)-type hydrogen storage alloy rare earths

Investigation of Coercivity Mechanism for Nd-Fe-B Magnets Prepared by Combination of strip-casting with Hydrogen Decrepitation Techniques

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Journal of Rare Earths 2003年第5期21卷 555-557页

作者：李波胡季帆王东玲郭炳麟王新林 Department of Functional Materials Central Iron & Steel Research Institute Department of Physics Shandong University

The coercivity mechanism of Nd Fe B magnets prepared by combination of strip casting with hydrogen decrepitation techniques was investigated. The microstructure of (Nd 0.935 Dy 0.065 ) 14.5 Fe 79.4 B 6.1 magnet was observed. The average grain size is about 6～12 μm. The magnetizing field dependence of the hardmagnetic properties for the (Nd 0.935 Dy 0.065 ) 14.5 Fe 79.4 B 6.1 and the temperature dependence of the coercivity for the Nd 14.5 Fe 79.4 B 6.1 were investigated. Results show that the coercivity for magnets prepared by the combination of strip casting with hydrogen decrepitation techniques is controlled by the nucleation mechanism.

关键词： metal materials NdFeB magnet Strip casting hydrogen decreipitation nucleation mechanism rare earths