Thixoforming : Semi-solid Metal Processing

352j 9 Rheocasting of Aluminium Alloys and Thixocasting of Steels
Figure 9.37 Comparison between the simulation and reality; the
displayed detail edge length is always 500 mm.
shape factors rise. With fewer grains the formation of large dendrites is advantaged,
but for casting such semi-solid slurries are unsuitable.
On balance, an increase in the heat flux to 5 J s 1 seems to be useful. In that case,
the aimed for solid fraction of about 50% will be achieved in less than 3 min.
To check the results, experiments were carried out using a pressurized air cooling
device coupled to the already described steel sheet moulds, shown in Figure 9.38. To
decrease the temperature loss over the front wall of the mould, Al2O3 insulating mats
were used. Before this insulation was inserted, the temperature differed by 8 C from
the centre to the billet edge, and afterwards it was only 3 C. This leads to a
Figure 9.38 Steel sheet mould with cooling device.