Thixoforming : Semi-solid Metal Processing

Figure 10.24 Design and working principle of the holding cup with cutting system of excess slurry.
of the part in the dies (step 3). Finally, the upper die opens and the part is ejected by
raising the plunger.
The given part geometry is characterized by a long flow length in the bush and a
large decrease in cross-section (ratio of area A to B) in Figure 10.26. To investigate the
microstructure state at four chosen points, all parts are divided along the axis of
symmetry.
The investigation on X210CrW12 shows a similar microstructure in the flange and
the bush (positions 1, 3 and 4) in Figure 10.27. It consists of a mixture of austenitic
grains and former liquid phase, which is solidified as a eutectic structure or partially
as ledeburite for fractions with higher carbon content. The mean grain size of this
region is around 50 mm. In contrast to the flange and the bush, austenitic phase
dominates in the centre of the part s body (position 2). The different development of
Figure 10.25 Schematic view of forming steps.
Figure 10.26 Positions of micrographs in vertical cross-section
(1–4) and different sizes of the cross-sections (A and B).
10.3 Heating and Forming Operationsj397