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Computational Material Science,
46(3):761-766
2009
ISSN: 0927-0256
Resume: A multiphase model for Ti-6Al-4V is proposed. This material is widely used in industrial applications and so needs accurate behaviour modeling. Tests have been performed in the temperature range from 25 degrees C to 1020 degrees C and at strain rates between 10(-3) s(-1) and 1 s(-1). This allowed the identification of a multiphase mechanical model coupled with a metallurgical model. The behaviour of each phase is calibrated by solving an inverse problem including a phase transformation model and a mechanical model to simulate tests under thermomechanical loadings. A scale transition rule (beta-rule) is proposed in order to represent the redistribution of local stresses linked to the heterogeneity of plastic strain. Finally this model is applied to two laser assisted processes: direct laser fabrication and laser welding. (C) 2009 Elsevier B.V. All rights reserved. Equipe: Département SI2M : Microstructures et Contraintes |
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Journal of Materials Science,
44(2):632-638
2009
ISSN: 0022-2461
Resume: In this study, hypoeutectoid Fe-N binary specimens have been prepared by gas nitriding pure iron in austenite domain at 840 A degrees C. The slow cooling of these specimens led to the alpha-ferrite + gamma'-Fe(4)N pearlitic microstructure which is similar to the pearlite in Fe-C binary system. This pearlitic microstructure has been characterized by electron microscopy. The crystal structure of the gamma'-Fe(4)N nitride has been identified by electron microdiffraction and the Nishiyama-Wassermann (N-W) and near Kurdjumov-Sachs (K-S) orientation relationships have been found between the alpha-ferrite and the gamma'-Fe(4)N. Equipe: Département SI2M : Microstructures et Contraintes |
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International Journal of Thermal Sciences,
48:795--804
2009
Equipe: Département SI2M : Microstructures et Contraintes |