Analysis by Micromechanical Modeling on Material Flow under Rapid Compression in the Semi-Solid State

Abstract:

Different types of semi-solid processing are used to produce a variety of components. In this context, the use of FE simulations to obtain the filling of the dies and to optimize the semi-solid processing is clearly of a great interest. To carry it out properly in an isothermal case, the semi-solid flow into the die and friction phenomena have to be correctly described. In addition, comparisons between experiments and simulations are needed to assess the reliability of the modeling and to improve the understanding of the processing. In situ visualization of the semi-solid flow during processing is complex since the dies are closed and opaque. One of the main recent work with transparent glass sided dies to film die filling is that by Atkinson and Ward (2006). The purpose of this work is to compare numerical simulations to these experiments. Numerical simulations were performed with the solid mechanics-based software FORGE©. A micromechanical model accounting for the liquid and solid behaviour and their spatial distribution within the material (Favier et al, 2009) was used. The model parameters were identified using rapid compression tests on the A357 aluminium alloy (Favier and Atkinson, 2011). The slurry temperature corresponds to 0.5 solid fraction. Comparisons were focused on the flow behaviour. The impact of the presence of an obstacle and of the shape of the obstacle was investigated. The numerical simulations reproduced quite well the flow behaviour for the case with and without central obstacle. However, the change in flow due to an increase of the ram speed from 250 mm/s to 1000 mm/s is not captured.

• Periodical: Solid State Phenomena (Volumes 217-218)
• Pages: 182-187
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.217-218.182
• Online since: September 2014
• Authors: Adriana Neag*, Véronique Favier, Régis Bigot, Helen V. Atkinson
• Keywords: Aluminium Alloy, Numerical Simulation, Rapid Compression, Semi-Solid, Solid Fraction

References

[1] H.V. Atkinson and P.J. Ward, Flow visualization for semi-solid processing, JOM 58 (6) 21-23 Jun 2006 and Ward et al. , Final Report for EPSRC Project: Modelling of Thixotropic Flow of Metal Alloys into a Die, – GR/M17334/01 – March 2002 (copy available at http: /www2. le. ac. uk/departments/engineering/people/academic-staff/helen-atkinson).

DOI: 10.1007/s11837-006-0174-x

[2] M. Hufschmidt, M. Modigell, J. Petera, Modelling and simulation of forming processes of metallic suspensions under non-isothermal conditions, J. Non-Newtonian Fluid Mech. 134 (2006) 16–26.

DOI: 10.1016/j.jnnfm.2005.10.006

[3] P. Cezard, V. Favier, R. Bigot, T. Balan, M. Berveiller, Simulation of semi-solid thixoforging using a micro-macro constitutive equation, Computational Materials Science 32 (2005) 323–328.

DOI: 10.1016/j.commatsci.2004.09.036

[4] V. Favier, P. Cezard, R. Bigot, Transient and non-isothermal semi-solid behaviour: 3D micromechanical modeling, Materials Science and Engineering A 517 (2009) 8−16.

DOI: 10.1016/j.msea.2009.03.018

[5] V. Favier, H.V. Atkinson, Micromechanical modelling of the elastic–viscoplastic response of metallic alloys under rapid compression in the semi-solid state, Acta Materialia 59 (2011) 1271–1280.

DOI: 10.1016/j.actamat.2010.10.059

[6] D. Liu, H.V. Atkinson, H. Jones, Thermodynamic prediction of thixoformability in alloys based on the Al–Si–Cu and Al–Si–Cu–Mg systems, Acta Mater. 53 (2005) 3807-3819.

DOI: 10.1016/j.actamat.2005.04.028

[7] T Y Liu, H V Atkinson, P J Ward and D H Kirkwood, Response of semi-solid Sn 15%Pb to rapid shear rate changes, Metall. and Mater. Trans. A. 34A (2003) 409-417.

DOI: 10.1007/s11661-003-0342-3