Forgeabilité des aciers inoxydables austéno-ferritiques

tel-00672279, version 1 - 21 Feb 2012
148 Chapter IV. STRAIN PARTITIONING
Figure IV.25, Figure IV.26 and in Appendix C). In the present investigation, the out-of-plane strain was
estimated using the isochoric assumption (no volume variation). In most cases, as the out-of-plane
strain component is insignificant compared to the in plane strain components, this method seems rela-
tively justified.
Several authors have attempted to provide an estimation of the out-of-plane displacement.
Soppa et al. [133] compared the strain distributions measured by the microgrid method in an
Ag/Ni(57%)-particulate composite taking or not into account the out-of-plane displacement. The out-of-
plane displacement was measured on a sample deformed at 8.6% under uniaxial compression at
room temperature by atomic force microscopy. The authors found that the discrepancies between the
two strain distributions were so small, that the corrections could be neglected, at least for the testing
conditions used.
Hernandez-Castillo et al. [50] has measured at the surface of some deformed microgrid samples the
out-of-plane displacement with a laser scanning confocal microscope. Figure IV.44.a and Figure
IV.44.b show an example of an optical micrograph and the corresponding topological image, of a small
area from a deformed microgrid of a laboratory duplex steel sample. Height profiles corresponding to
the vertical and horizontal lines in Figure IV.44.b were plotted in order to quantify out-of-plane dis-
placement. Some enhanced local out-of-plane displacement was observed, see Figure IV.44.c and
Figure IV.44.d. However, the authors concluded that the displacements were such that they would not
result in significantly different strain values.