Thixoforming : Semi-solid Metal Processing

Figure 6.49 Microstructure of A356 feedstock produced by the
cooling channel after holding for 120 s in the container.
Figure 6.50 The computed shear rate (s 1 ) in the melt over the channel near CP2 at 2.3 s.
6.3.4
Summary
The MeSES code was applied successfully to simulate the formation of semi-solid
feedstock using the cooling channel process. The models implemented within the
code exhibited a satisfactory response to the variation of different process parameters.
The results agree with expectations and have the same trend as the experimental
results in the literature [37, 46]. After application of the experimentally determined
grain nucleation parameters, the results were improved and became more reliable in
the absence of melt convection and shear. In the presence of shear flow, the grain
density and grain diameter values deviated from the experiments. Further study of
the effect of shear and vigorous melt convection during continuous cooling of molten
alloys on grain nucleation and multiplication is highly recommended.
List of Symbols
T _
v _
tensor
vector
6.3 Simulation of Cooling Channelj215