Pressure-driven mold filling model of aluminum alloy melt/semi-solid slurry based on rheological behavior

doi:10.1016/j.jmst.2019.07.048

Abstract

Abstract:

The pressure-driven mold filling ability of aluminum alloy melt/semi-solid slurry is of great significance in pressure casting processes, and the rheological behavior of the alloy has a crucial effect on the mold filling ability according to fluid dynamics. In this work, a pressure-driven mold filling model is first proposed based on the rheological behavior of the alloys. A356 alloy is employed as an example to clarify the rheological behavior of aluminum alloys, which obeys the power law model and is affected by temperature. The rheological behavior of the alloy in semi-solid state is modelled with the coupling of shear rate and temperature. The stop of mold filling attributes to the pressure loss which is caused by the viscosity during the flow of the melt/semi-solid slurry. Pressure loss caused by viscous flow and heat transfer between the alloy and the mold are calculated and coupled during the mold filling of the melt/semi-solid slurry. A pressure-driven mold filling model of aluminum alloy melt/semi-solid slurry is established based on steady-state rheological behavior. The model successfully predicts the filling length of melt/semi-solid slurry in pressure casting processes. Compared with the experimental results, the model can provide a quantitative approach to characterize the pressure-driven mold filling ability of aluminum alloy melt. The model is capable of describing the stop filling behavior of other aluminum alloys in pressure casting processes with corresponding rheological parameters and heat transfer coefficient.

Key words: Mold filling model, Fluidity, Pressure-driven, Rheological behavior, Aluminum alloys, Semi-solid state

Zhen Ma, Huarui Zhang, Wei Song, Xiaoyan Wu, Lina Jia, Hu Zhang. Pressure-driven mold filling model of aluminum alloy melt/semi-solid slurry based on rheological behavior[J]. J. Mater. Sci. Technol., 2020, 39: 14-21.

Figures/Tables 16

Table 1 A356 alloy composition (wt%).

Si	Mg	Fe	Cu	Ti	Sr	Zn	Ni	Al
7.128	0.346	0.111	0.089	0.145	0.0144	0.006	0.005	Bal.

Fig. 1. Concentric-cylinder device of high-temperature rotational rheometer.

Fig. 2. Rheological experimental procedure.

Fig. 3. Evolution of apparent viscosity with time at 600 ℃.

Fig. 4. Relationships between steady-state viscosity and (a) shear rate and (b) temperature.

Fig. 5. (a) Experimental and (b) Loué et al’s [28] results and fitting curves of steady-state viscosity.

Table 2 Fitting parameters of steady-state viscosity and peak viscosity.

Temperature (℃)	561	573	580	585	590	595	600	605	610
n-1	-0.958	-1.015	-1.306	-1.294	-1.179	-1.093	-1.128	-1.167	-1.078
logK	7.642	6.599	5.779	5.647	5.076	3.994	3.687	3.510	3.406
R²	0.999	0.987	0.999	0.999	0.998	0.999	0.998	0.997	0.999

Fig. 6. Experimental data and fitting curves of n-1 and logK versus temperature.

Fig. 7. Comparison of the experimental data and the viscosity model under different temperatures (a) and shear rates (b).

Fig. 8. Schematic diagram of the filling of the melt/semi-solid slurry in a circular tube.

Table 3 Thermophysical properties of A356 alloy.

Liquid density, ρ₁ (kg/m³)	Specific heat, C₁ (J/(kg ℃))	Liquid viscosity, η_l (Pa s)	Enthalpy of solidification, L (J/kg)
2512	1150	0.001	4.29 × 10⁵

Fig. 9. Solid fraction versus temperature and the fitting curve.

Fig. 10. Pressure-driven mold filling ability of A356 alloy melt in circular tube of different diameters: filling length versus (a) pressure and driving temperature, (c) temperature, and (d) driving pressure, and (b) driving pressure versus temperature.

Fig. 11. Pressure loss of the alloy in different diameter tube and at different temperatures poured at 700 ℃.

Table 4 The process parameters used in the model.

Pouring temperature	700-730 ℃
Mold temperature	Room temperatue
Pressure difference	3545 Pa
Hydraulic diameter of the cross section	5.71 mm
Flow velocity	1.19 m/s
Interfacial heat transfer coefficient	3500 W/(m² ºC)

Fig. 12. Comparison between experimental and modelling results.

References

[1]	I. Gutierrez-Urrutia, M.A Mu˜noz-Morris, D.G Morris, Acta Mater. 55 (2007) 1319-1330.
[2]	O. Lashkari, F. Ajersch, A. Charette, X.G. Chen, Mater. Sci. Eng. A 492 (2008) 377-382.
[3]	X. Wu, H. Zhang, F. Zhang, Z. Ma, L. Jia, B. Yang, T. Tao, H. Zhang, Mater. Charact. 139 (2018) 116-124.
[4]	V.E. Bazhenov, A.V. Petrova, A.V. Koltygin, Int. J. Metalcast. 12 (2018) 514-522.
[5]	K.R. Ravi, R.M. Pillai, K.R. Amaranathan, B.C. Pai, M. Chakraborty, J. Alloys. Compd. 456 (2008) 201-210.
[6]	Q. Han, H. Xu, Scr. Mater. 53 (2005) 7-10.
[7]	G. Chen, M. Yang, Y. Jin, H. Zhang, F. Han, Q. Chen, Z. Zhao, J. Mater. Process. Technol. 266 (2019) 19-25.
[8]	H. Mirzadeh, B. Niroumand, J. Mater. Process. Technol. 209 (2009) 4977-4982.
[9]	G. Timelli, F. Bonollo, Int. J. Cast Met.Res. 20 (2007) 304-311.
[10]	P. Semanco, M. Fedák, M. Rimár, E. Ragan, Adv. Mater. Res. 505 (2012) 190-194.
[11]	G. Lang, Aluminium 49 (1973) 231-238.
[12]	S. Gowri, F.H. Samuel, Metall. Mater. Trans. A 25 (1994) 437-448.
[13]	G. Timelli, D. Caliari, Mater. Sci. Forum 884 (2017) 71-80.
[14]	M. Di Sabatino, L. Arnberg, Int. J. Cast Met.Res. 18 (2013) 181-186.
[15]	W. Prukkanon, N. Srisukhumbowornchai, C. Limmaneevichitr, J. Alloys. Compd. 487 (2009) 453-457.
[16]	Y. Bai, W. Mao, S. Gao, G. Tang, J. Xu, J. Univ. Sci. Technol. B 15 (2008) 48-52.
[17]	N.J. Humphreys, D. McBride, D.M. Shevchenko, T.N. Croft, P. Withey, N.R. Green, M. Cross, Appl. Math. Model. 37 (2013) 7633-7643.
[18]	M.D. Sabatino, Fluidity of Aluminium Foundry Alloys, Ph.D. Thesis, Norwegian University of Science and Technology, 2005.
[19]	M. Flemings, Br. Foundryman 57 (1964) 312-325.
[20]	Q. Han, S. Viswanathan, Mater. Sci. Eng. A 364 (2004) 48-54.
[21]	M. Flemings, E. Niyama, H. Taylor, AFS Trans. 69 (1961) 625-635.
[22]	Y. Zhou, J. Northwest. Polytech. Univ. 1 (1964) 89-99.
[23]	P. Das, S.K. Samanta, P. Dutta, Metall. Mater. Trans. B 46 (2015) 1302-1313.
[24]	X.G. Hu, Q. Zhu, S.P. Midson, H.V. Atkinson, H.B. Dong, F. Zhang, Y.L. Kang, Acta Mater. 124 (2017) 446-455.
[25]	X.G. Hu, Q. Zhu, H.V. Atkinson, H.X. Lu, F. Zhang, H.B. Dong, Y.L. Kang, Acta Mater. 124 (2017) 410-420.
[26]	R. Meshkabadi, V. Pouyafar, A. Javdani, G. Faraji, Metall. Mater. Trans. A 48 (2017) 4275-4285.
[27]	H. Atkinson, Prog. Mater. Sci. 50 (2005) 341-412.
[28]	W. Loué, M. Suery, J. Querbes, Proceedings of 2nd International Conference Processing of Semi-Solid Alloys and Composites, MIT, Cambridge, USA, 1992.
[29]	B.R. Munson, T.H. Okiishi, W.W. Huebsch, A.P. Rothmayer, Fluid Mechanics, Wiley, Singapore, 2013, pp. 278-317.
[30]	R.B. Bird, R.C. Armstrong, O. Hassager, Fluid Mechanics, vol. 1, Wiley, New York, 1987, pp. 321-328.
[31]	B. Zhang, D.M. Maijer, S.L. Cockcroft, Mater. Sci. Eng. A 464 (2007) 295-305.