Thixoforming : Semi-solid Metal Processing

404j 10 Thixoforging and Rheoforging of Steel and Aluminium Alloys
Figure 10.34 Temperature distribution in the component for different stages (ABAQUS).
solidified and more homogeneous regarding the temperature distribution. The
subsequent cooling in air (t ¼ 3 s) that occurs during to the ejection of the component
leads to further homogenization of the temperature field in the whole component
because of the reduced heat transfer into the tools.
To clarify the influence of different materials and dwell durations, the temperatures
of two positions of the component are measured with pyrometers after opening
the cavity. The comparison considers simulated and experimental results for the
defined measuring points (Figure 10.35). Generally, the tendencies and the level of
the simulated temperatures of TZM fit the measured values. The simulated results
for the hot forming tool steel dies are about 100 C lower than the results for TZM. In
any case, the flange shows a lower temperature than the middle of the component
because less heat has to be transmitted into the die. Depending on the measuring
point and the contact time, the measured temperature can increase with time because
the heat flow from the inner part of the component is greater than the heat losses due
to radiation and the convective heat transmission to the surroundings.
The comparison of the simulated results between the considered tool materials
shows a significant difference in the cooling behaviour of the component. Concern-