One of the major challenges in simulation of semi-solid forming is characterizing the complex behavior of a material that consists of both solid and liquid phases. In this study, a material model for an A356 alloy in a semi-solid state has been developed for high solid fractions (>0.6) and implemented into a finite element simulation tool to investigate the micro-/mesoscale feature formation during the forming process. Compared to previous stress models, which are limited to expressing the stress dependency on only the strain rate and the temperature (or the solid fraction), the proposed stress model adds the capability of describing the semi-solid material behavior in terms of strain and structural evolution. The proposed stress model was able to explain the strain-softening behavior of the semi-solid material. Furthermore, a simulation model that includes the yield function, the flow rule, and the stress model has been developed and utilized to investigate the effects of various process parameters, including analysis type (isothermal vs nonisothermal), punch velocity, initial solid fraction, and workpiece shape (“flat” versus “tall”) on the micro-/mesofeature formation process.

1.
Burgos
,
G. R.
,
Alexandrou
,
A. N.
, and
Entov
,
V.
, 2001, “
Thixotropic Rheology of Semisolid Metal Suspensions
,”
J. Mater. Process. Technol.
0924-0136,
110
, pp.
164
176
.
2.
Mada
,
M.
, and
Ajersch
,
F.
, 1996, “
Rheological Model of Semi-Solid A356-Sic Composite Alloys. Part 1: Dissociation of Agglomerate Structures During Shear
,”
Mater. Sci. Eng., A
0921-5093,
212
, pp.
157
170
.
3.
Charreyron
,
P. O.
, and
Flemings
,
M. C.
, 1985, “
Rheology of Semi-Solid Dendritic Sn-Pb Alloys at Low Strain Rates: Application to Forming Process
,”
Int. J. Mech. Sci.
0020-7403,
27
(
11/12
), pp.
781
791
.
4.
Suery
,
M.
, and
Flemings
,
M. C.
, 1982, “
Effect of Strain Rate on Deformation Behavior of Semi-Solid Dendritic Alloys
,”
Metall. Trans. A
0360-2133,
13A
, pp.
1809
1819
.
5.
Spencer
,
D. B.
,
Mehrebian
,
R.
, and
Flemings
,
M. C.
, 1972, “
Rheological Behavior of Sn-15% Pb in the Crystallization Range
,”
Metall. Trans.
0026-086X,
3
, pp.
1925
1932
.
6.
Kiuchi
,
M.
, 1979, “
Extrusion of Alloy in Mushy-State
,”
J. Jpn. Soc. Technol. Plast.
0038-1586,
20
, pp.
826
833
.
7.
Kiuchi
,
M.
, 2001, “
Flow Stress, Yield Criterion and Constitutive Equation of Mushy/Semisolid Alloys
,”
CIRP Ann.
0007-8506,
50
, pp.
157
160
.
8.
Shima
,
S.
, and
Oyane
,
M.
, 1976, “
Plasticity Theory for Porous Metals
,”
Int. J. Mech. Sci.
0020-7403,
18
, pp.
285
291
.
9.
Nguyen
,
T.
,
Favier
,
D.
, and
Suery
,
M.
, 1994, “
Theoretical and Experimental Study of the Isothermal Mechanical Behavior of Alloys in the Semi-Solid State
,”
Int. J. Plast.
0749-6419,
10
(
6
), pp.
663
693
.
10.
Martin
,
C. L.
,
Brown
,
S. B.
,
Favier
,
D.
, and
Suery
,
M.
, 1995, “
Shear Deformation of High Solid Fraction (>0.60) Semi-Solid Sn-Pb Under Various Structures
,”
Mater. Sci. Eng., A
0921-5093,
A202
, pp.
112
122
.
11.
Kumar
,
P.
,
Martin
,
C. L.
, and
Brown
,
S. B.
, 1993, “
Shear Rate Thickening Flow Behavior of Semi-Solid Slurries
,”
Metall. Trans. A
0360-2133,
24A
, pp.
1107
1116
.
12.
Kumar
,
P.
,
Martin
,
C. L.
, and
Brown
,
S. B.
, 1994, “
Constitutive Modeling and Characterization of the Flow Behavior of Semi-Solid Metal Alloy Slurries-1. The Flow Response
,”
Acta Metall. Mater.
0956-7151,
42
(
11
), pp.
3595
3602
.
13.
Gunasekera
,
J. S.
, and
Zhou
,
Z.
, 1992, “
Development of a Constitutive Model for Mushy (Semi-Solid) Materials
,” 2nd International Conference on Semi-Solid Processing of Alloys and Composites, MIT, Cambridge, pp.
211
222
.
14.
Gunasekera
,
J. S.
, and
Zhou
,
Z.
, 1997, “
Mechanics of Semi-Solid Material
,”
Proceedings of the 1997 TMS Annual Meeting
, Orlando, pp.
733
743
.
15.
Pinsky
,
D. A.
,
Charreyron
,
P. O.
, and
Flemings
,
M. C.
, 1984, “
Compression of Semi-Solid Dendritic Sn-Pb Alloys at Low Strain Rates
,”
Metall. Trans. B
0360-2141,
15B
, pp.
173
181
.
16.
Laxmanan
,
V.
, and
Flemings
,
M. C.
, 1980, “
Deformation of Semi-Solid Sn-15 Pct Pb Alloy
,”
Metall. Trans. A
0360-2133,
11A
, pp.
1927
1937
.
17.
Salvo
,
L.
,
Loue
,
W. R.
, and
Suery
,
M.
, 1995, “
Influence of Prior Solidification Conditions on the Structure and Rheological Behavior of Partially Remelted Al-Si Alloys
,”
ISIJ Int.
0915-1559,
35
, pp.
798
804
.
18.
Koc
,
M.
,
Vazquez
,
V.
,
Witulski
,
T.
, and
Altan
,
T.
, 1996, “
Application of the Finite Element Method to Predict Material Flows and Defects in the Semi-Solid Forging of A356 Aluminum Alloys
,”
J. Mater. Process. Technol.
0924-0136,
59
, pp.
106
112
.
19.
Yoon
,
J. H.
,
Im
,
Y. T.
, and
Kim
,
N. S.
, 1999, “
Rigid-Thermoviscoplastic Finite-Element Analysis of the Semisolid Forging of Al2024
,”
J. Mater. Process. Technol.
0924-0136,
89-90
, pp.
104
110
.
20.
Yoon
,
J. H.
,
Im
,
Y. T.
, and
Kim
,
N. S.
, 2001, “
Finite Element Modeling of the Deformation Behavior of Semi-Solid Materials
,”
J. Mater. Process. Technol.
0924-0136,
113
, pp.
153
159
.
21.
Ko
,
D.-C.
,
Min
,
G.-S.
, and
Choi
,
J.-C.
, 2000, “
Finite Element Analysis for the Semi-Solid State Forming of Aluminum Alloy Considering Induction Heating
,”
J. Mater. Process. Technol.
0924-0136,
100
, pp.
95
104
.
22.
Kang
,
C. G.
,
Jung
,
H. K.
, and
Jung
,
K. W.
, 2001, “
Thixoforming of an Aluminum Component With a Die Designed by Process Simulation
,”
J. Mater. Process. Technol.
0924-0136,
111
(
1–3
), pp.
37
41
.
23.
Malvern
,
L.
, 1969,
Introduction to the Mechanics of a Continuous Medium
,
Prentice-Hall
, Englewood Cliffs.
24.
Lewandowski
,
M. S.
, and
Overfelt
,
R. A.
, 1999, “
High Temperature Deformation Behavior of Solid and Semi-Solid Alloy 718
,”
Acta Mater.
1359-6454,
47
(
18
), pp.
4695
4710
.
25.
Li
,
D.
, and
Ghosh
,
A.
, 2003, “
Tensile Deformation Behavior of Aluminum Alloys at Warm Forming Temperatures
,”
Mater. Sci. Eng., A
0921-5093,
352
, pp.
279
286
.
26.
Sigworth
,
G. K.
, 1996, “
Rheological Properties of Metal Alloys in the Semi-Solid State
,”
Can. Metall. Q.
0008-4433,
35
(
2
), pp.
101
133
.
27.
Hokao
,
M.
,
Hironaka
,
S.
,
Suda
,
Y.
, and
Yamamoto
,
Y.
, 2000, “
Friction and Wear Properties of Graphite/Glassy Carbon Composites
,”
Wear
0043-1648,
237
, pp.
54
62
.
28.
Peterson
,
M.
, and
Johnson
,
R.
, 1956, “
Friction Studies of Graphite and Mixtures of Graphite With Several Metallic Oxides and Salts at Temperatures to 1000f
,” Technical Note 3657 National Advisory Committee for Aeronautics, pp.
1
16
.
29.
Jeong
,
D. J.
,
Kim
,
D. J.
,
Kim
,
J. H.
,
Kim
,
B. M.
, and
Dean
,
T. A.
, 2001, “
Effects of Surface Treatments and Lubricants for Warm Forging Die Life
,”
J. Mater. Process. Technol.
0924-0136,
113
, pp.
544
550
.
30.
Jung
,
H. K.
, and
Kang
,
C. G.
, 2002, “
Induction Heating Process of an Al-Si Aluminum Alloy for Semi-Solid Die Casting and Its Resulting Microstructure
,”
J. Mater. Process. Technol.
0924-0136,
120
, pp.
355
364
.
31.
Dughiero
,
F.
,
Forzan
,
M.
, and
Lupi
,
S.
, 2003, “
Reheating 150Mm Billets of A356 Alloy for Thixo-Processing
,” International Scientific Colloquium, Hannover, Mar. 24–26, pp.
177
182
.
You do not currently have access to this content.