Forgeabilité des aciers inoxydables austéno-ferritiques

tel-00672279, version 1 - 21 Feb 2012
Appendices 177
Appendix A: Post processing-analysis of the raw data of
the plane strain compression tests
A.1 Specimens measurements
The undeformed and deformed specimens were measured as described in Figure A. 1.
a) b)
Figure A. 1. Schematic diagram of a testpiece; a) before and b) after testing, and approximate dimensional
measurement positions.
For the thickness, the measurements were averaged over five readings. In the breadth direction the
average was weighted towards the central measurement, with this being counted twice during the
calculation. The cold final measurements were then used to calculate the hot final measurements of
the specimen using eq A.1:
hh h f � h f ( T�
T0
� �
)
eq A.1
where hh is the hot thickness, hf is the deformed cold thickness, α is the thermal expansion coefficient,
T the deformation temperature and T0 is room temperature.
A.2 Breadth spread, origin and machine compliance corrections
It was impractical to use a specimen geometry for which the tool width was not a significant factor of
the specimen breadth. This led to lateral spread of the specimen and uncertainty in the contact area
when the stress was applied. An ‘instantaneous’ breadth was empirically defined following the test, to
take into account the changing contact area between the tools and the specimen.