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Transformation martensitique et rupture différée dans l'acier austénitique instable 301LN

Abstract : The automotive industry requires increasingly steels with good combination of high strength and good formability. Unstable austenitic stainless steels combine these properties, making them very attractive. However, under specific conditions in the field of drawing, delayed cracking phenomenon can appears in this kind of steels. The aim of this work is the study of the delayed cracking phenomenon related to the martensitic transformation in the 301LN unstable austenitic stainless steel. For that, we divided this work into two parts: Thermomechanical Behaviour : This part deals with the characterization of martensitic transformation after uniaxial loading under different of temperature and strain rate conditions. The stress distribution between the phases, the martensitic transformation kinetics, and the evolution of crystallographic texture are determined by X Rays Diffraction (XRD) under uniaxial in-situ tensile tests. Multi-scales analysis of the delayed cracking phenomenon : study of the delayed cracking phenomenon are done on deep drawing cups. The identification of microstructural parameters which are responsible of crack initiation is realised by Scanning Electronic Microscopy (SEM). For different conditions of drawing, both, macroscopic residual stress and residual stress distribution between phases are determined and associated to the martensite content in the cups. Numerical simulations of deep drawing process are realised by implementation of two martensitic transformation models in the unstable austenitic steels. Numerical results are compared to our experimental results. We establish a relation between stress state in the martensite, volume fraction of formed martensite, and the delayed cracking phenomenon.
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https://pastel.archives-ouvertes.fr/pastel-00002460
Contributor : Ecole Arts Et Métiers Paristech <>
Submitted on : Monday, June 4, 2007 - 8:00:00 AM
Last modification on : Monday, April 16, 2018 - 10:41:41 AM
Long-term archiving on: : Thursday, September 30, 2010 - 8:13:31 PM

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  • HAL Id : pastel-00002460, version 1

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Mohamed Reda Berrahmoune. Transformation martensitique et rupture différée dans l'acier austénitique instable 301LN. Sciences de l'ingénieur [physics]. Arts et Métiers ParisTech, 2006. Français. ⟨NNT : 2006ENAM0041⟩. ⟨pastel-00002460⟩

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