Thixoforming : Semi-solid Metal Processing

Extrusion load (kN)
50
40
30
20
10
0
100
76
0 10 20 30 40 50 60 70 80 90
11.4.4
Summary and Discussion
Displacement (mm)
Figure 11.14 Typical load curve versus displacement for upscaled steel thixoextrusion experiments.
Figure 11.15 Industrial-scale isothermal thixoextrusion extruded
X210CrW12 bar and metallographic analysis.
11.4 Isothermal Thixoextrusionj427
Isothermal steel thixoextrusion experiments were successfully performed by applying
the tool concept of self-heating ceramic dies. Analysis of extruded bars proved the
beneficial influence of isothermal semi-solid processing on microstructure and
properties of work pieces, as depicted in Section 11.4.2. Moreover, on the example
of steel X210CrW12, the realization of an improvement in highly application-relevant
work alloy properties such as hardness and Young s modulus, as predicted in
metallurgical investigations (cf. Chapter 3), was demonstrated. Results prove that
not only may forming forces be reduced and the geometric complexity of the formed
parts be increased, but also that the homogeneity and thus uniformity of mechanical
properties of the work alloy might be improved by isothermal semi-solid processing.
However, tool construction and process control still remain critical aspects for
isothermal thixoextrusion of steels. The present experiments revealed a pronounced
sensitivity of ceramic tool setups to thermal gradients and unplanned mechanical