Thixoforming : Semi-solid Metal Processing

Carbon content (%)
4,0
3,5
3,0
2,5
2,0
1,5
1,0
tip centre
1 2 3 4 5 6 7 8 9 10 11 12 13
Sample
Owing to the difficulties in determining the former liquid-phase content of quenched
samples, as discussed by P€uttgen et al. [11], these elements act as a reliable indicator
of phase segregation.
The values for both alloying elements are within the fluctuation range of
X210CrW12 as given by the material supplier, indicated by the grey areas in
Figure 11.10, except for the carbon content at the bar tip.
Hardness and Young s modulus measured by nanoindentation on straight lines at
positions near the middle (position 2) and the bar end (position 3) revealed two levels
of values. Correlation of both properties is high, as indicated by the averaged results
given in Table 11.3.
Moreover, accompanying scanning electron microscopic analysis revealed a
correlation of nanoindentation results with microstructural characteristics. Low-level
end
Figure 11.10 Carbon and chromium contents of as-extruded bars.
Numbering of sampling points 1–13 refers to the sampling
scheme given in Figure 11.8.
Table 11.3 Hardness and Young s modulus values [GPa] calculated from nanoindentation experiments a .
Nano indention data
Cross-section
C
Cr
13
12
11
10
Position 2 Position 3
11.4 Isothermal Thixoextrusionj423
9
8
7
Chromium content (%)
Average
Hardness Overall 7.0 (2.7) 7.7 (3.5) 7.4
Base level 5.7 (0.8) 6.4 (0.6) 6.1
High level 11.2 (2.2) 14.2 (4.8) 12.7
Young s modulus Overall 228 (17) 238 (23) 233
Base level 218 (11) 233 (11) 226
High level 246 (9) 280 (19) 263
a Standard deviations are given in parentheses. Sampling positions are given in Figure 11.9.