Thixoforming : Semi-solid Metal Processing

area which is available for heat treatment and hot working operations. The C content
has been chosen to yield the maximum temperature range in this phase field. The
solidification sequence is complex, starting with primary ferrite, switching to
peritectic formation of austenite followed by the formation of (at least) M6C and
MC carbides. Figure 5.16 shows the liquid fraction as a function of temperature
calculated with different methods. As for the other steels, the standard Scheil
calculation does not produce useful results. The modified Scheil and equilibrium
calculation are very similar above 30% liquid. A DICTRA simulation (not shown) at a
slightly different composition gave results similar to the modified Scheil calculation.
However, the DICTRA simulation was only possible using a number of tricks.
Acknowledgement
The authors gratefully acknowledge financial support from the Deutsche Forschungsgemeinschaft
(DFG) within the Collaborative Research Centre (SFB) 289
Forming of metals in the semi-solid state and their properties .
List of Abbreviations and Symbols
DFG Deutsche Forschungsgemeinschaft
DTA differential thermal analysis
fL liquid fraction
T50 temperature at which there is 50% liquid
TL liquidus temperature
TM7C3 temperature where eutectic (M7C3) formation starts
TS (equilibrium) solidus temperature
DH enthalpy change
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