双辊冷却低过热度浇铸结晶器内钢水流场温度场耦合数值模拟
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摘要
本论文提出了一种低过热度浇注技术,即“通过旋转的冷却辊将液态金属冷却,并强迫其注入结晶器”,为有效解决低过热度浇铸工艺带来的水口堵塞问题提出了一种新方法。利用CFD商用软件Fluent分别对双辊冷却低过热度浇铸方坯连铸和薄板坯连铸结晶器内钢水的流场、温度场及凝固场在不同拉速情况下做了模拟与分析,并与浸入式水口浇铸下结晶器内钢水的流动及凝固状况进行了比较。为验证双辊冷却低过热度浇铸对改善铸坯组织的有效性,以99%的工业铝为实验材料,研究了经“U”型管冷却的铝液在低过热度浇铸下铝锭铸坯的宏观组织及力学性能。
论文研究结果表明:
(1)钢液经冷却辊冷却浇入结晶器内,由于冷却辊对浇铸钢液起到了冷却作用,过热度变小,实现了低过热度浇铸的目的。随着拉速的提高,冷却辊的冷却作用相对变小。
(2)流场分析表明钢液经冷却辊注入结晶器形成向下的冲击流,一方面该冲击流有利于打断凝固前沿的柱状晶,从而形成新的形核驱动力,扩大等轴晶率;另一方面冲击流冲击到一定深度产生上旋回流涡,该回流涡有利于钢液中夹杂物的去除和保护渣的熔化。
(3)双辊冷却浇铸与浸入式水口浇铸相比,结晶器内钢液的温度场分布、凝固壳生长均均匀,且温度梯度小、液固两相区宽,有利于提高等轴晶率,抑制柱状晶的生长;同时可降低铸坯凝固组织中的中心偏析、疏松以及裂纹等缺陷的产生。
(4)以工业铝为实验材料进行实验研究,结果表明低过热度浇铸下铝铸锭的宏观组织得到了改善和细化,且铝铸件的强度极限得到了较为显著的提高。
A kind of low superheat forces pouring technology is introduced in this paper, that is, the liquid metal is poured into mould by cooling roller, a new approach is introduced to solve the problem of water mouth blinding in low-superheat casting technology. By the aid of CFD business software—Fluent, flow field, temperature field and solidification field of the molten steel in mould are simulated and analyzed for billet casting mold and thin slabs casting mold poured by two rollers cooling in low superheat at different pull velocity. At the same time, the conclusion is compared with the flow-state and solidification of the molten steel in mould with immersion water mouth poured. Finally, in order to verify the validity of simulation data, the macro organization and mechanics characters of aluminum ingot which is cooled through“U”pipe at low superheat casting are studied for the experimental material of 99% industrial aluminum. The conclusion in the paper show:
(1) For the refrigeration by cooling roller, the steel liquid is poured into mould realizing the purpose of casting at lower superheat. As the increasing of pull velocity, the cooling roller actions play down relatively.
(2) Flow field shows that steel liquid is poured into mould by cooling roller and form shock stream downward. On the one hand, the shock stream breaks up the syllogistic crystal of solidification front, then the new driving force will be formed and the isometric crystal rate will be enlarged. On the other hand, the shock stream brings convolute backset at certain depth, which is helpful to exclude the field trash in steel liquid and melt the protecting dregs.
(3) Compared with immersion water mouth casting, the distribution of temperature field and the growing of solidification shell of the steel liquid in mould by two rollers cooling casting at low superheat are uniform. Moreover, the steel liquid in mould by two rollers cooling casting at low superheat has little gradient of temperature and wide two-phase district of liquid and solid. It is favorable to raise paraxial crystal rate, inhibit syllogistic crystal growth, and degrade center-segregation, defect rate of loose and slight crackle in the organization of casting slab.
(4) With the experimental material of industrial aluminum, the result shows that macro organization of the aluminum ingot casting by cooling rollers at low superheat is improved and its ultimate stress is refined greatly.
论文研究结果表明:
(1)钢液经冷却辊冷却浇入结晶器内,由于冷却辊对浇铸钢液起到了冷却作用,过热度变小,实现了低过热度浇铸的目的。随着拉速的提高,冷却辊的冷却作用相对变小。
(2)流场分析表明钢液经冷却辊注入结晶器形成向下的冲击流,一方面该冲击流有利于打断凝固前沿的柱状晶,从而形成新的形核驱动力,扩大等轴晶率;另一方面冲击流冲击到一定深度产生上旋回流涡,该回流涡有利于钢液中夹杂物的去除和保护渣的熔化。
(3)双辊冷却浇铸与浸入式水口浇铸相比,结晶器内钢液的温度场分布、凝固壳生长均均匀,且温度梯度小、液固两相区宽,有利于提高等轴晶率,抑制柱状晶的生长;同时可降低铸坯凝固组织中的中心偏析、疏松以及裂纹等缺陷的产生。
(4)以工业铝为实验材料进行实验研究,结果表明低过热度浇铸下铝铸锭的宏观组织得到了改善和细化,且铝铸件的强度极限得到了较为显著的提高。
A kind of low superheat forces pouring technology is introduced in this paper, that is, the liquid metal is poured into mould by cooling roller, a new approach is introduced to solve the problem of water mouth blinding in low-superheat casting technology. By the aid of CFD business software—Fluent, flow field, temperature field and solidification field of the molten steel in mould are simulated and analyzed for billet casting mold and thin slabs casting mold poured by two rollers cooling in low superheat at different pull velocity. At the same time, the conclusion is compared with the flow-state and solidification of the molten steel in mould with immersion water mouth poured. Finally, in order to verify the validity of simulation data, the macro organization and mechanics characters of aluminum ingot which is cooled through“U”pipe at low superheat casting are studied for the experimental material of 99% industrial aluminum. The conclusion in the paper show:
(1) For the refrigeration by cooling roller, the steel liquid is poured into mould realizing the purpose of casting at lower superheat. As the increasing of pull velocity, the cooling roller actions play down relatively.
(2) Flow field shows that steel liquid is poured into mould by cooling roller and form shock stream downward. On the one hand, the shock stream breaks up the syllogistic crystal of solidification front, then the new driving force will be formed and the isometric crystal rate will be enlarged. On the other hand, the shock stream brings convolute backset at certain depth, which is helpful to exclude the field trash in steel liquid and melt the protecting dregs.
(3) Compared with immersion water mouth casting, the distribution of temperature field and the growing of solidification shell of the steel liquid in mould by two rollers cooling casting at low superheat are uniform. Moreover, the steel liquid in mould by two rollers cooling casting at low superheat has little gradient of temperature and wide two-phase district of liquid and solid. It is favorable to raise paraxial crystal rate, inhibit syllogistic crystal growth, and degrade center-segregation, defect rate of loose and slight crackle in the organization of casting slab.
(4) With the experimental material of industrial aluminum, the result shows that macro organization of the aluminum ingot casting by cooling rollers at low superheat is improved and its ultimate stress is refined greatly.
引文
[1]陈雷主编.连续铸钢[M].北京:冶金工业出版社,1993
[2]蔡开科.浇注与凝固[M].北京冶金工业出版社,1994
[3]冯文圣,赵继宇,易卫东.低过热度浇铸工艺在高碳钢连铸生产中的应用[J].连铸,2005,2:15～16
[4] Nitin A. Shah and John J. Moore. Macro segregation in Continuously Cast High Carbon Steel Billets. 1983 Steelmaking Proceedings, 66: 247-259
[5]熊守美,许庆彦,康进武编著.铸造过程模拟仿真技术[M].机械工业出版,2004
[6]朱诚意,李光强,饶江平,等.连铸薄板坯的质量缺陷及其改善措施研究[J],上海金属,2006,28(2):15-20
[7]任建义,胡进洲,张瑞忠,等.减少薄板坯表面纵裂的工艺探讨[J].河北冶金,2004,(6):37-38
[8]翔编著.现代连铸新工艺新技术与铸坯质量控制[M].北京:当代中国出版社,2004.8
[9] Thomas BG.Modeling of the continuous casting of steel past, present and future [C].Iron&Steel Soc. Elect Furnace Div.Iron&Steel Soc. Process Technol Div.2001
[10]徐志洋,姜红军.小方坯连铸机漏钢事故分析及防止措施[J].马钢科研,1999,(4): 7-11.
[11]张学田,张怀宾,岳峰,等.小方坯连铸漏钢原因分析及预防措施[J].炼钢,2006,22(5): 15-18
[12]倪满森.降低出钢温度实现低过热度连铸[J].炼钢,1999,15(5):10-13
[13]张朝晖,金波,巨建涛,等.新临钢连铸板坯中间裂纹的成因分析与改进措施[J].上海金属, 2006, 28(5): 21-24
[14]魏立国,徐国栋,朱岩,等.宝钢厚板连铸板坯三角区裂纹改善的研究[J].宝钢技术, 2006, 4: 16-20
[15] Wang, YH .A Study of the Effect of Casting Conditions on Fluid Flow in the Mold Using Water Modeling.73rd Steelmaking Conference,Defroit.USA.1990, V61, 73-75
[16]薛正良,李正邦,张家雯.高碳钢连铸方坯中心偏析[J].炼钢, 2000,16(1): 56-59
[17] N. A. Shah, J. J. Moor. A Review of the Effect of Electromagnetic Stirring (EMS) in Continuously Cast Steel Part I. Iron & Steelmaker, 1982, 9 (10): 317-376
[18]熊井浩,浅野钢一等.连铸铁片内の凝固偏析现象と溶钢流动に关系すめ研究铁と钢, 1974, 60(7): 894-914
[19]大野笃美著,刑建东译.金属的凝固—理论、实践及实用[M].北京:机械工业出版社, 1990年
[20] P. Naveau, S.Wilmotte, C. Albreeq.Casting at Near Liquids Temperature [C]. METEC Congress 94, 2nd European Continuous Casting Conference, 6th International Rolling Conference Dusseldorf, June 20-22, 1994: 228-233
[21] P. Naveau. Development of a heat exchanger for casting with low superheat [J]. La revue de Metallurgies’CIT, Mars 1993: 395-401
[22] Henderson, S. Scholes. A, Clarke. BD. Continuous Casting of High Carbon Steel in Billet and Bloom Sections at Sub-Liquids Temperatures.Commission of the European Communities (EUR13623), 1991: 108
[23] Kenzo a., Hideo M., Kazuyuki T. Hiromu M. Low Superheat Teeming with Electromagnetic Stirring [J]. ISIJ Int. 1995, 35(6): 680-685
[24]毛卫民,杨继莲,赵爱民等.浇铸温度对AlSi7Mg合金半固态组织的影响[J].北京科技大学学报,2001,23(1):38～41
[25]荆涛.凝固过程数值模拟[M].北京:电子工业出版社,2002
[26] Clyde T W. Numerical modeling of directional solidification of metallic alloys [J].Met.Sci, 1982, 16:441-450
[27]王艳春,耿茂鹏,张莹,等.双辊铸轧AZ91D半固态镁合金板带试验研究[J].铸造技术,2006,27(2):139-141
[28]金珠梅,赫冀成,徐广隽.双辊连续铸轧工艺中流场、温度场和热应力场的数值计算.金属学报,2000,36(40):391-394
[29]毛卫民,赵爱民,崔成林,等.AlSiMg合金半固态连铸坯料和组织形成研究.金属学报,2000,36(5):539-544
[30]崔小朝,王宥宏,林金宝等.一种内外复合冷却高效连铸结晶器[P].中国专利:2004 2 0016771.1
[31]崔小朝.基于结晶器内钢水内外复合冷却原理高效连铸技术的研究.国家自然科学基金(编号:50474013),2005
[32]崔小朝,晋艳娟,张柱,等.板坯连铸内外复合冷却流场和温度场耦合数值模拟[J].钢铁研究学报,2007,19(8):14-18
[33]崔小朝,刘梓才,宋静,等.内外复合冷却高效结晶器内钢水三维流场数值模拟[J].特殊钢,2005,26(1):9-11
[34]丁祖荣编著.流体力学[M].北京:高等教育出版社,2003
[35]干勇,仇圣桃,萧泽强.连续铸钢过程数学物理模拟[M].北京:冶金工业出版社,2001,17-18
[36]杨世铭,陶文铨.传热学[M].高等教育出版社,1998
[37] Louhenkilpi S.Modeling of heat transfer in continuous casting [C].Materials science forum balaton fured, Hungary.2003, 414-416,445-454
[38]熊守美,许庆彦,康进武编著.铸造过程模拟仿真技术[M].机械工业出版社,2004
[39]柳百成,荆涛等编著.铸造工程的模拟仿真与质量控制[M].机械工业出版社,2001
[40]候增寿,卢光熙主编.金属学原理[M].上海科学技术出版社,1990,7
[41]胡汉起.金属凝固原理[M].北京:机械工业出版社,1987
[42]李庆春编.铸件成形理论基础[M].哈尔滨工业大学出版社,1980
[43]周建兴等,凝固过程数值模拟中的潜热处理方法[J].铸造,2001.7,404
[44]大中逸雄.计算机传热凝固解析入门[M].北京:机械工业出版社,1998
[45]王福军.计算流体动力学分析─CFD软件原理与应用[M],北京,清华大学出版社,2004
[46] Launder B E, Spalding D B. Mathematical Models of Turbulence. London: Academic Press,1972
[47]萧泽强,朱苗勇等编著.冶金过程数值模拟分析技术的应用.北京:冶金工业出版社,2006
[48] Chavez JF, Celaya A .Heat transfer in mold flux-layers during slab continuous casting[J].Stall making proceedings.1996,321-329
[49]陈家祥.连续铸钢手册.北京:冶金工业出版社,1991:165-168
[50]崔小朝,史荣,曾建潮.变形体凝固传热焓式有限元数学模型与过程仿真.系统仿真学报,1997,9(4):29-34
[2]蔡开科.浇注与凝固[M].北京冶金工业出版社,1994
[3]冯文圣,赵继宇,易卫东.低过热度浇铸工艺在高碳钢连铸生产中的应用[J].连铸,2005,2:15～16
[4] Nitin A. Shah and John J. Moore. Macro segregation in Continuously Cast High Carbon Steel Billets. 1983 Steelmaking Proceedings, 66: 247-259
[5]熊守美,许庆彦,康进武编著.铸造过程模拟仿真技术[M].机械工业出版,2004
[6]朱诚意,李光强,饶江平,等.连铸薄板坯的质量缺陷及其改善措施研究[J],上海金属,2006,28(2):15-20
[7]任建义,胡进洲,张瑞忠,等.减少薄板坯表面纵裂的工艺探讨[J].河北冶金,2004,(6):37-38
[8]翔编著.现代连铸新工艺新技术与铸坯质量控制[M].北京:当代中国出版社,2004.8
[9] Thomas BG.Modeling of the continuous casting of steel past, present and future [C].Iron&Steel Soc. Elect Furnace Div.Iron&Steel Soc. Process Technol Div.2001
[10]徐志洋,姜红军.小方坯连铸机漏钢事故分析及防止措施[J].马钢科研,1999,(4): 7-11.
[11]张学田,张怀宾,岳峰,等.小方坯连铸漏钢原因分析及预防措施[J].炼钢,2006,22(5): 15-18
[12]倪满森.降低出钢温度实现低过热度连铸[J].炼钢,1999,15(5):10-13
[13]张朝晖,金波,巨建涛,等.新临钢连铸板坯中间裂纹的成因分析与改进措施[J].上海金属, 2006, 28(5): 21-24
[14]魏立国,徐国栋,朱岩,等.宝钢厚板连铸板坯三角区裂纹改善的研究[J].宝钢技术, 2006, 4: 16-20
[15] Wang, YH .A Study of the Effect of Casting Conditions on Fluid Flow in the Mold Using Water Modeling.73rd Steelmaking Conference,Defroit.USA.1990, V61, 73-75
[16]薛正良,李正邦,张家雯.高碳钢连铸方坯中心偏析[J].炼钢, 2000,16(1): 56-59
[17] N. A. Shah, J. J. Moor. A Review of the Effect of Electromagnetic Stirring (EMS) in Continuously Cast Steel Part I. Iron & Steelmaker, 1982, 9 (10): 317-376
[18]熊井浩,浅野钢一等.连铸铁片内の凝固偏析现象と溶钢流动に关系すめ研究铁と钢, 1974, 60(7): 894-914
[19]大野笃美著,刑建东译.金属的凝固—理论、实践及实用[M].北京:机械工业出版社, 1990年
[20] P. Naveau, S.Wilmotte, C. Albreeq.Casting at Near Liquids Temperature [C]. METEC Congress 94, 2nd European Continuous Casting Conference, 6th International Rolling Conference Dusseldorf, June 20-22, 1994: 228-233
[21] P. Naveau. Development of a heat exchanger for casting with low superheat [J]. La revue de Metallurgies’CIT, Mars 1993: 395-401
[22] Henderson, S. Scholes. A, Clarke. BD. Continuous Casting of High Carbon Steel in Billet and Bloom Sections at Sub-Liquids Temperatures.Commission of the European Communities (EUR13623), 1991: 108
[23] Kenzo a., Hideo M., Kazuyuki T. Hiromu M. Low Superheat Teeming with Electromagnetic Stirring [J]. ISIJ Int. 1995, 35(6): 680-685
[24]毛卫民,杨继莲,赵爱民等.浇铸温度对AlSi7Mg合金半固态组织的影响[J].北京科技大学学报,2001,23(1):38～41
[25]荆涛.凝固过程数值模拟[M].北京:电子工业出版社,2002
[26] Clyde T W. Numerical modeling of directional solidification of metallic alloys [J].Met.Sci, 1982, 16:441-450
[27]王艳春,耿茂鹏,张莹,等.双辊铸轧AZ91D半固态镁合金板带试验研究[J].铸造技术,2006,27(2):139-141
[28]金珠梅,赫冀成,徐广隽.双辊连续铸轧工艺中流场、温度场和热应力场的数值计算.金属学报,2000,36(40):391-394
[29]毛卫民,赵爱民,崔成林,等.AlSiMg合金半固态连铸坯料和组织形成研究.金属学报,2000,36(5):539-544
[30]崔小朝,王宥宏,林金宝等.一种内外复合冷却高效连铸结晶器[P].中国专利:2004 2 0016771.1
[31]崔小朝.基于结晶器内钢水内外复合冷却原理高效连铸技术的研究.国家自然科学基金(编号:50474013),2005
[32]崔小朝,晋艳娟,张柱,等.板坯连铸内外复合冷却流场和温度场耦合数值模拟[J].钢铁研究学报,2007,19(8):14-18
[33]崔小朝,刘梓才,宋静,等.内外复合冷却高效结晶器内钢水三维流场数值模拟[J].特殊钢,2005,26(1):9-11
[34]丁祖荣编著.流体力学[M].北京:高等教育出版社,2003
[35]干勇,仇圣桃,萧泽强.连续铸钢过程数学物理模拟[M].北京:冶金工业出版社,2001,17-18
[36]杨世铭,陶文铨.传热学[M].高等教育出版社,1998
[37] Louhenkilpi S.Modeling of heat transfer in continuous casting [C].Materials science forum balaton fured, Hungary.2003, 414-416,445-454
[38]熊守美,许庆彦,康进武编著.铸造过程模拟仿真技术[M].机械工业出版社,2004
[39]柳百成,荆涛等编著.铸造工程的模拟仿真与质量控制[M].机械工业出版社,2001
[40]候增寿,卢光熙主编.金属学原理[M].上海科学技术出版社,1990,7
[41]胡汉起.金属凝固原理[M].北京:机械工业出版社,1987
[42]李庆春编.铸件成形理论基础[M].哈尔滨工业大学出版社,1980
[43]周建兴等,凝固过程数值模拟中的潜热处理方法[J].铸造,2001.7,404
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