Thixoforming : Semi-solid Metal Processing

Figure 3.43 Microstructure development of the steel X210CrW12
after differently paced coolings from 1210 C after prior
annealing in the partial liquid state (1270 C/30 min).
In the following, the experiments of the third test series are discussed. The samples
were annealed at 1270 C, quenched and subsequently held isothermally for 1–168 h
at 490 C, for 1–24 h at 540 C and for 30–75 min at 595 C. Figure 3.44 shows that at
an ageing temperature of 490 C a maximum hardness of 800 HV10 is reached after
an annealing time of 100 h, at 540 C a maximum hardness of 745 HV10 is reached
after 10 h and at the highest annealing temperature of 595 C a maximum hardness of
720 HV10 is reached after 30 min. In conformity with previously published research
on high-chromium content steels [51, 65], an examination of the microstructure
Figure 3.44 Hardness as a function of the ageing time for
annealing temperatures of 490, 540 and 595 C.
3.6 Microstructure Analysis and Material Propertiesj93