摘要
在钢锭连铸过程中,合金熔体的传热、传质和熔体流动是凝固过程中重要的传输现象,这些传输行为决定着铸锭的结晶质量。同时凝固过程各个传输现象之间彼此紧密关联并相互影响,加入电磁场后会使这种耦合传输现象更加复杂。因此,研究电磁连铸凝固过程中耦合传输现象,揭示电磁场作用下钢凝固传输行为的规律,可为优化工艺参数提高铸件质量提供依据,具有重要的研究意义。
本文以理论建模和计算机模拟为研究手段,基于本课题组已有的研究工作,将凝固传热、传质及动量传输的耦合传输统一模型应用到电磁连铸过程,以实现钢锭连铸系统电磁场和凝固传输的耦合传输数值模拟。为此,本论文进行了如下研究工作:
建立了在电磁场与重力场共同作用下,连铸钢锭相对实验室静止坐标系以一定的抽拉速度V0运动的电磁凝固过程传热、传质与动量传输的耦合数学模型与数值计算方法。采用FORTRAN语言编制了电磁连铸的凝固传输计算程序,实现了电磁连铸凝固传输的耦合数值模拟。
采用ANSYS软件分析计算了本论文钢锭电磁连铸过程所施加的电磁场,包括不同强度的横向静磁场和不同形式的行波电磁场。利用本试验室自行研发的FORTRAN有限元/有限差数据格式转换技术,将ANSYS计算的基于有限元分析的电磁场的计算结果转换为凝固传输计算程序可读的有限差格式的数据。
将电磁场计算结果耦合到连铸凝固传输计算程序中,初步实现了钢锭连铸凝固传输与电磁场的耦合数值模拟。模拟结果包括:液相流场、固相分数场、洛仑兹力场、温度场和成分场等。进行了无磁场仅重力场作用下钢锭连铸凝固传输的数值计算,表明本文所建立的相对静止坐标系运动条件下电磁连铸系统凝固传输耦合模型及数值计算方法是可行的。进行了初步的静磁场/行波电磁场和重力场共同作用下的连铸钢锭凝固传输行为的耦合数值模拟计算,分析了不同强度的磁场对液相流场的抑制作用,考察了不同极对数的行波电磁场对连铸钢锭凝固过程的影响。
The solidification transport phenomena (STP), i.e. heat, mass and momentum transfer in alloy solidification systems are very important and complicated due to the strong coupling among them. When an electromagnetic filed (EMF) is applied to the solidifying system, that coupled correlations will becom even more complicated. Research on the coupled solidification transport phenomena and the influence of EMF on the solidified process of steel ingot can give advice to improve the quality of ingots, and is very meaningful.
The aim of the present thesis is to establish an EM-coupled continuum model for STP in the electromagnetic continuous casting (CC) processes of steel ingots based on the previous work of our research group, using the method of theoretical modeling and computer simulation. The main work inclued:
The mathematical model in a continuum form and the corresponding numerical formula for the electromagnetic STP of the steel ingot in EMC process are established, which is under both gravity and electromagnetic fields and with a movement velocity V0 relatively to the static lab coordinate. Computer codes in FORTRAN language is developed for numerical simulation of the EMC-STP processes.
The ANSYS software is explored to analyze the static and traveling magnetic fileds applied to the EMC system. Conversion of the EMF-data from ANSYS finite element method (FEM) format, included the B vector field, induction current density, Joule heat and so on, to finite different method (FDM) format is performed using our own data processing FORTRAN program.
Coupling the conversed EMF-data to the STP simulation program, preliminary computational results, including the liquid flow velocity, temperature filed, solid volume fraction filed, Lorentz force filed and so on in EM-continuous casting processes of steel ingots, indicate that the present computer modeling is successful.
The coupled simulation results for the CC-STP behaviors under different static and traveling EMFs show that, application of a static magnetic field to the steel ingot continuous casting process can effectively suppress the bulk liquid flow, and the braking effects enhance with the increase of the magnetic field’s intensity; the application of traveling magnetic field can obviously change the liquid flow patterns.
引文
1张军,付恒志,谢发勤,沈军,李建国.金属熔体的电磁成形与凝固.材料研究学报. 1997,11(6): 612~622
2 S.Asai. Recent Development and Prospect of Electromagnetic Processing of Material Science and Technology of Advanced Materials. 2000,(1): 191~200
3毛丽贺.电磁场下钛合金叶片定向凝固传输行为计算机模拟.哈尔滨工业大学硕士学位论文,2003:5
4李双明,李金山,郝启堂等.金属熔体的电磁近终成形技术.中国机械工程. 2000,11(1-2):73~76
5 Vives C. Electromagnetic Refining of Aluminum Alloys by the CREM Process: Part I.Working Principle and Metallurgical Results[J]. Metall. Trans. B. 1989, 20B(10):623~629
6邓康,任忠鸣,蒋国昌.软接触电磁连铸的数值模拟和实验分析.金属学报. 1999, 35(10):112~1114
7王宏明,任忠鸣,雷作胜等.钢的软接触电磁连铸技术.铸造技术. Sep.2005, 26(9):782~784
8 S.N.TEWARI, RAJESH SHAN, Hui SONG. Effect of Magnetic Field on the Microstructure and Macrosegregation in Directionally Solidfied Pb-Sn Alloys. Metallurigical and Materials Transactions A. 1994, 25A:1535~1544
9 Eiichi Takeuch. Applying MHD Technology to the Continuous Casting of Steel Slab. JOM. MAY. 1995:42~45
10 Yun-Seong HWANG et al. Numerical Analysis of the Influences of Operational Parameters on the Fluid Flow and Meniscus Shape in Slab Caster with EMBR. ISIJ International. 1997,37(7):659~667
11张宏丽,王恩刚等.电磁搅拌提高铸坯等轴晶比率的数值模拟.东北大学学报(自然科学版). 2001,22(5):535~538
12苏彦庆,毕维生,黄俊勇,张铁军.电磁铸造移动磁场发生器磁场分布规律及其作用分析.特种铸造及有色合金. 2005, 25(1):10~12
13张铁军.大型薄壁铝合金件移动磁场铸造充型过程基础研究.哈尔滨工业大学博士学位论文. 2003:11~17
14张宏丽等.线性电磁搅拌器电磁场分布的数值模拟.东北大学学报.2002,23(9):352~354
15麻永林,宿国栋,黄海娥,刘洪潇,胡慧明,王国栋.板坯行波电磁搅拌器磁场分布规律的实验研究. Journal of Baotou University of Iron and Steel Technology. 2005, 24(3):224~226
16久保田淳等.用移动磁场控制板坯连铸结晶器内的钢液流动重钢技术. 2002,2:27~33
17姚若琼,王义海,曹志强,张守魁.铝合金电磁净化的现状及前景.铸造. 2003,52(4): 227~229
18 Zhong Yun-Bo, Ren Zhong-Ming, Deng Kang, Xu Kuang-Di. Separation of Inclusions from Liquid Metal Contained in a Triangle/Square Pipe by Traveling Magnetic Field. Trans. Nonferrous Met. Soc. China. 2000, 10(2): 240~245
19 Nobuyuki GENMA, Toshiyuki SOEJIMA, Tadashi SAITO, Masayasu KIMURA, Hirohiko FUKUMOOTO and Kenzo AYATA. The Linear-motor Type In-mold Electromagnetic Stirring Technology for the Continuous Caster. ISIJ International. 1989,29(12):1056~1062
20邓安元,贾光霖,赫冀成.软接触结晶器内的钢液流动及夹杂物运动规律.东北大学学报(自然科学版). 2001,122(3):311~314
21陈芝会等.板坯连铸结晶器内电磁制动控制效果的研究. Research on Iron & Steel. 2005, 5:11~14
22战东平,张慧书等.连铸结晶器电磁制动对铸坯中非金属夹杂物影响的研究.铸造技术. 2007, 28(1):110~113
23张志峰,钢电磁连续铸造技术的研究.大连理工大学博士学位论文, 2001:6
24 Yuji Miki. Applications of MHD to Continuous Casting of Steel. The 5th International Symposium on Electromagnetic Processing of Materials, 2006, Sendai, Japan, ISIJ:26~30
25 Takehiko Toh, Eiichi Takeuchi and Tooru Matsumiya. Recent Advances in MHD Applications to Steelmaking Processes. The 5th International Symposium on Electromagnetic Processing of Materials, 2006, Sendai, Japan, ISIJ:21~25
26 Yang Hongliang, Zhang Xingzhong, Qiu Shengtao, Deng Kaiwen, Li Wencai,Gan Yong. Mathermatical Study on EMBR in a Slab ContinuousCasting Process. Scandinavian Journal of Metallurgy. 1998, 27:196~204
27 Noriko Kubo, Jun Kubota, Makoto Suzuki. Molten Steel Flow Monitoring and Control by the EMLS in a Continuous Casting Mold. The 5th International Symposium on Electromagnetic Processing of Materials, 2006, Sendai, Japan, ISIJ:45~47
28张桂芳,沈厚发,王镭,柳百成.结晶器电磁制动钢液流场数值模拟.铸造. 2005,154(15):484~487
29 Tatyana P. Lyubimova, Arne Croell et al. Time-dependent Magnetic Field Influence on GaAs Crystal Growth by Vertical Bridgman Method. Journal of Crystal Growth. 2004(266):404~410
30 I. Grants, G. Gerbeth. Stability of Melt Flow Due to a Traveling Magnetic Field in a Closed Ampoule. Journal of Crystal Growth. 2004(269):630~638
31张北江,崔建忠,路贵民,张勤.外加电磁场对半连续铸造7075铝合金宏观偏析规律的影响.东北大学学报(自然科学版). 2002, 23(10):968~971
32赵志浩,崔建忠,左玉波,张海涛,张北江.低频电磁水平半连续铸造中磁场的分布及其对宏观偏析的影响. Foundry. 2005,154(13):241~245
33班春燕,韩逸,龙春仙,崔健忠,巴启先.铸造技术. 2006, 27(3):263~265
34 M.Medina, Y.Du Terral, F.Durand and Y.Fautrelle. Channel Segregation During Solidification and the Effect of an Alternating Traveling Magnetic Field. Metallurgical and Materials Transaction B. 2004,35B:743~754
35 K. Za?¨dat et al. Directional solidification of Refined Al–3.5wt% Ni Under Natural Convection and Under a Forced Flow Driven by a Travelling Magnetic Field. Journal of Crystal Growth. 2005 (275):1501~1505
36郝海,金俊泽.电磁铸造及其数值模拟的发展.特种铸造及有色合金. 1999,增刊第1期:128~130
37 B.Q. Li, J.W. Evans, and D.P. Cook. An Improved Mathematical Model for Electromagnetic Casters and Testing by a Physical Model. Metall.Trans. B. 1991, 22B:121~134
38 D. P. Cook, J. W. Evans. A Three-Dimensional Mathematical Model of Electromagnetic Casting and Testing Against a Physical Model: Part 1. The Mathematical Model. Metallurgical and Materials Transactions B. 1995, 26B(10):1263~1270
39 Man Y.Ha, Hyun G.Lee, Seung H. Seong. Numerical Simulation of Three-dimensional Flow, Heat Transfer, and Solidification of Steel in Continuous Casting Mold with Electromagnetic Brake. Journal of Materials Processing Technoligy. 2003,133:322~339
40 Amnon, J. Meir, Paul G. Schmidt et al. Numerical Simulation of Steady Liquid-metal Flow in the Presence of a Static Magnetic Field. Transactions of ASME. 2004,71:786~795
41张红伟,王恩刚,赫冀成.方坯连铸过程中钢液流动、凝固及溶质分布的藕合数值模拟. 2002,38(1): 99~104
42 Kwan_Gu, Hong-Sun Ryon and Nahm-Keon Hur. Coupled Trublent Flow, Heat Transfer in Continuous Casting Process with an Electromagnetic Brake. Numerical Heat Transfer,Part A. 2005(48):461~481
43李中原,赵九洲.薄板坯连铸凝固过程及溶质偏析的三维耦合数值模拟.特种铸造及有色合金. 2006,26(3): 150~154
44 Yunfeng Bai, Daming Xu et al. FEM/FDM-Joint Simulation For Transport Phenomena in Directionally Solidifying Shaped TiAl Casting under Electromagnetic Field ,ISIJ International, 2004,44(7):1173~1179
45 Daming Xu, Yunfeng Bai, Jingjie Guo and Hengzhi Fu. Numerical Simulation of Heat, Mass and Momentum Transport Behaviors in Directionally Solidifying Alloy Castings under Electromagnetic Fields Using an Extended Direct-SIMPLE Scheme. Int. J. Numerical Methods in Fluids. 2004, 46(7):767~791
46司广琚.钢锭凝固传输模型及宏观偏析的计算机模拟.哈尔并工业大学硕士学位论文. 1996
47崔庆新.钛合金水冷铜型电磁定向凝固传输耦合模型及计算机模拟.哈尔滨工业大学工学硕士学位论文. 2004
48徐达鸣.铸锭凝固过程宏观偏析计算机模拟的统一模型.哈尔滨工业大学博士学位论文. 1989, 3:16~18, 38~39
49 Daming Xu. A Unified Microscale-Parameter Approach to Solidification-Transport Phenomena-Based Macrosegregation Modeling for Dendritic Solidfication: Part I. Mixture Average-Based Analysis. Met. Mater. Trans. B. 2001,32B:1129~1141
50牛中奇,朱满座.电磁场理论基础.北京:电子工业出版社, 2001:35
51 D.M. Xu et al, Mass and Momentum Transport Behaviors in DirectionallySolidifying Bade-like Castings in Different Electromagnetic Fields Described Using a Continuum Model. International Journal of Heat and Mass Transfer. 2005 (48):2219~2232
52 S. V.帕坦卡.传热和流体流动的数值方法.郭宽良译,安徽:安徽科学技术出版社, 198:124
53 Daming Xu et al. Numerical Solution to T-φs-CL Coupling in Binary Dendrite Solidification with Any Solid-back Diffusion Effects. Trans. Nonferrous Met. Soc. China, 2003,13(5):1149~1154
54 Daming XU and Qingchun LI. Numerical Method for Solution of Strongly Coupled Binary Alloy Solidification Problems.Numerical Heat Transfer, Part A. 1991,20:181-201
55 Daming XU and Qingchun LI. Gravity and Solidification Shrinkage Induced Liquid Flow in a Horizontally Solidified Alloy Ingot. Numerical Heat Transfer, Part A. 1991, 20:203~221
56顾江平.定向凝固钢锭中宏观偏析的数值模拟及控制.清华大学机械工程系博士学位论文. 1995:10~55
57 T. Fujii, D.R. Poirier and M.C. Flemings, Macrosegregation in a Multicomposition Low Alloy Steel. Metal. Trans. 1979,10B:331~339
58陈家祥.炼钢常用图表数据手册.北京:冶金工业出版社.1984:30~75
59 Thermo-Calc Software AB. Thermo-Calc Software User’Guide Version Q. Foubdation of Computational Thermodynamics Stockholm Swenden, 2004:1~9
60 M.C.M. Cornelissen, Mathematical Model for Solidification of Multicomponent Alloys. Ironmaking and Steelmaking. 1986, 13(4):204~212
61王富耻,张朝晖. ANSYS10.0有限元分析理论与工程应用.北京:电子工业出版社. 2006:1~14
62美国金属学会.金属手册,第九版,第二卷.中国机械工业出版社. 1994:927
63胡庆生.现代电气工程使用技术手册(上册).机械工业出版社. 1994.10: 3~74