Forgeabilité des aciers inoxydables austéno-ferritiques
Forgeabilité des aciers inoxydables austéno-ferritiques
Forgeabilité des aciers inoxydables austéno-ferritiques
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tel-00672279, version 1 - 21 Feb 2012<br />
Chapter IV. STRAIN PARTITIONING 129<br />
Analyzing the strain cumulative distribution functions as indicated in Figure IV.30 allows estimating the<br />
ferrite content involved in the X% the most deformed with X = 1, 5, 10, 15, 20, 25 and 30%. The re-<br />
sults are given in Table IV.7 and confirm that the regions the more strained consist essentially of fer-<br />
rite.<br />
X% the more strained 1% 5% 10% 15% 20% 25% 30%<br />
%δ<br />
D1_W<br />
D2_W<br />
Map 1 90 ± 1 86 ± 1 82 ± 1 81 ± 1 78 ± 1 76 ± 1 83 ± 1<br />
Map 2 100 ± 1 88 ± 1 89 ± 1 86 ± 1 85 ± 1 85 ± 1 83 ± 1<br />
Map 1 90 ± 1 89 ± 1 87±1 85 ± 1 81 ± 1 78 ± 1 75 ± 1<br />
Map 2 90 ± 1 98 ± 1 95 ± 1 92 ± 1 90 ± 1 88 ± 1 85 ± 1<br />
Table IV.7. Ferrite content (%δ) in the areas the more deformed in both D1_W and D2_W microstructures.<br />
The strain maps provide qualitative information about the mechanisms involved in the high tempera-<br />
ture deformation of duplex stainless steels. Nevertheless, it is difficult to compare the two investigated<br />
gra<strong>des</strong> with only spatial information. Additional quantitative characterizations are therefore necessary<br />
to discriminate both microstructures.<br />
IV.5.2 Discussion<br />
The results presented in section IV.5.1 give a relatively good overview of the mechanisms involved in<br />
the high temperature deformation of duplex steels, however, a few points require discussion in more<br />
details. The discussions are conveyed in the form of questions/answers.<br />
IV.5.2.1 What is the origin of the difference between D2_W and D1_W in<br />
terms of strain partitioning?<br />
IV.5.2.1.1 Question<br />
The results clearly demonstrate that the strain partitioning contrast between ferrite and austenite is<br />
smaller in the D1_W microstructure compared to the D2_W microstructure. Naturally, the question is<br />
to determine the origin of this difference.<br />
IV.5.2.1.2 Answer<br />
It could also be interesting to compare the D1_W austenite with the D2_W austenite and the D1_W<br />
ferrite with the D2_W ferrite. Such comparisons require normalizing the average deformation per<br />
phase by the overall strain in the region of interest as shown in Table IV.8.<br />
D1_W<br />
D2_W<br />
�<br />
� eq<br />
�<br />
� / �<br />
overall<br />
eq<br />
�<br />
� eq<br />
�<br />
� / �<br />
Map 1 0.87 1.12<br />
Map 2 0.89 1.08<br />
Average 0.88 1.10<br />
Map 1 0.80 1.22<br />
Map 2 0.78 1.24<br />
Average 0.79 1.23<br />
overall<br />
eq<br />
Table IV.8. Normalization of the average deformation per phase by the overall strain in the region<br />
of interest for both D1_W and D2_W microstructures.
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