WATER MODELING OF MOULD FILLING DURING SUCTION CASTING PROCESS OF AUTOMOTIVE EXHAUST VALVES OF γ-TiAl BASED ALLOYS
XIONG Chao, MA Yingche, CHEN Bo, LIU Kui, LI Yiyi
Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016
Cite this article:
XIONG Chao MA Yingche CHEN Bo LIU Kui LI Yiyi. WATER MODELING OF MOULD FILLING DURING SUCTION CASTING PROCESS OF AUTOMOTIVE EXHAUST VALVES OF γ-TiAl BASED ALLOYS. Acta Metall Sin, 2011, 47(11): 1408-1417.
Abstract Investment and suction casting represents a more cost effective route to produce automotive exhaust valves of γ-TiAl based alloys, but the castings have severe gas porosities in the preliminary suction casting. It has been conferred that the generation of the porosity defects in the castings is a result directly associated with the entrapped air during filling flow. In order to investigate the filling patterns and the entrapped air during the suction casting process of automotive exhaust valves of γ-TiAl based alloys, water modeling experiments have been done. The effect of three types of filling pressure control methods and two types of moulds on the filling patterns are systematically investigated in this paper. Results show that serious entrapped air occur during the filling flow with an rough pressure control method by means of the vents at the top of the moulds (called a general suction casting); Tranquil filling patterns are obtained under an accurate pressure control method (“gas charging” or “air leakage”), and if the gas charging flow is smaller than 1.7 m3/h or the air leakage flow is smaller than 1.5 m3/h, the entrapped air phenomenon disappear. Meanwhile, the general and the“air leakage” suction casting of TiAl automotive exhaust valves are implemented using the conclusions of the corresponding water modeling experiments, and the real casting results claim good qualitative agreement with that of the water modeling experiments. Finally, The reasonable explanation for the aforementioned results of the water modeling experiments is given using the filling kinetic principle of suction casting.
[1] Clemens H, Kestler H. Adv Eng Mater, 2000; 2: 551
[2] Yamaguchi M, Inui H, Ito K. Acta Mater, 2000; 48: 307
[3] HartfieldWunsch S E, Sperling A A, Morrison R S, DowlingWE, Allison J E. In: Kim YW,Wagner R, Yamaguchi M eds., Gamma Titanium Aluminides. Warrendale, PA: Minerals, Metals and Materials Soc, 1995: 41
[4] Dowling W E, Donlon W T, Allison J E. In: Horton J, Baker I, Hanada S, Noebe R D, Schwartz D S eds., High–Temperature Ordered Intermetallic Alloys. Pittsburgh, PA: Materials Research Soc, 1995: 757
[5] Gebauer K. Intermetallics, 2006; 14: 355
[6] SmarslyW, Baur H, Glitz G, Clemens H, Khan T, Thomas M. In: Hemker K J, Dimiduk D M, Clemens H, Darolia R, Inui H, Larsen J M, Sikka V K, Thomas M, Whittenberger
J D eds., Structural Intermetallics 2001, Warrendale, PA: Minerals, Metals and Materials Soc, 2001: 25
[7] Chandley G D. AFS Trans, 1976; 84: 37
[8] Chandley G D, Cargill D L. AFS Trans, 1990; 98: 413
[9] Giese S R, Dix L. AFS Trans, 1999; 107: 217
[10] Koitzsch R, Odenthal H J, Pfeifer H. Steel Res Int, 2007; 78: 473
[11] Buchholz A, Ji M S, Schmitz W, Engler S. In: Huglen R ed., Technical Session on Light Metals 1997, the 126th TMS Annual Meeting, Worrendale, PA: Minerals, Metals and Materials Soc, 1997: 1043
[12] Odenthal H J, Bolling R, Pfeifer H. Steel Res Int, 2003; 74: 35
[13] Zhao Z W, Gao Y, Zhang H. Spec cast Nonferrous Alloy, 2007; 27: 351
(赵志维, 高永, 张 虎. 特种铸造及有色合金, 2007; 27: 351)
[14] Li C Y, Wu S P, Guo J J, Su Y Q, Bi W S, Fu H Z. J Mater Process Technol, 2006; 176: 268
[15] Tu X. Basic Theories and Method of Model Experiment. Xi’an: Northwestern Polytechnical University Press, 1989: 51
(屠 兴. 模型实验的基本理论与方法. 西安: 西北工业大学出版社, 1989: 51)
[16] Bai Y F. PhD Thesis, Harbin Institute of Technology, 2002
(白云锋. 哈尔滨工业大学博士论文, 2002)
[17] Xia T C. Engineering Fluid Mechanics. Shanghai: Shanghai Jiao Tong University Press, 2006: 5
(夏泰淳. 工程流体力学. 上海: 上海交通大学出版社, 2006: 5)
[18] Dong X Q, Wang D, Wang C Z, Li Y H, Guo G S, Wang Y C, Liu Z M. Theory and Practice of Low Pressure and Counter Pressure Casting, 3rd Ed., Beijing: China Machine Press, 2003:124
