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Suivi de l'état de contraintes, appliquées et internes, des alliages ferromagnétiques doux par mesure de leur propriétés magnétiques

Abstract : A strong coupling exists between mechanical and magnetic properties of ferromagnetic materials. The aim of this study is to lead to a better understanding of the physical mechanisms involved, with the practical aim of developing magnetic methods for nondestructive evaluation of the mechanical state. The experimental characterisations have been carried out mainly on a non-oriented Fe-(3wt.%)Si electrical steel. The mechanical behaviour under an uniaxial tensile test is characterised by the existence of two strain-hardening stages, related to the evolution of the dislocations feature. Furthermore, a strong kinematic hardening value, representative of the internal stresses state, is reached from the very beginning of the plastic deformation. An appropriate experimental device has been created and magnetic measurements have been performed under uniaxial tensile stresses approaching and exceeding the macroscopic elastic limit Σe and in the corresponding unloaded states. Both Barkhausen noise and B-H hysteresis loops were measured. The different stages of the tensile deformation (perfectly elastic stage, microplastic yielding stage, the two strain-hardening stages) are clearly identified by the magnetic parameters. By using measurements on prestrained specimens under reloaded elastic stresses, an accurate identification of the effect of dislocations acting as pinning sites and of the magnetoelastic effect of long-range internal stresses has been proposed. Additional characterisations of a high-purity polycrystalline nickel and of a FeCo-(2wt.%)V alloy have confirmed our hypothesis.
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https://tel.archives-ouvertes.fr/tel-00010845
Contributor : Viorel Iordache <>
Submitted on : Tuesday, November 1, 2005 - 1:10:47 PM
Last modification on : Friday, May 17, 2019 - 1:59:52 PM
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Viorel-Eugen Iordache. Suivi de l'état de contraintes, appliquées et internes, des alliages ferromagnétiques doux par mesure de leur propriétés magnétiques. Matériaux. Université de Technologie de Compiègne, 2003. Français. ⟨tel-00010845⟩

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