Suzanne Degallaix - Academia.edu (original) (raw)
Uploads
Papers by Suzanne Degallaix
Procedia Engineering, 2010
Cyclic variations of temperature may damage a component, or a part of a component. Such a phenome... more Cyclic variations of temperature may damage a component, or a part of a component. Such a phenomenon is called 'thermal fatigue'. In most cases, multiple cracking occurs. It is also sometimes called 'crazing'. The so- called SPLASH experiment, described in this paper, allows the experimental reproduction of crack networks similar to those actually observed in some parts of pressurized water reactors. Thus, the initiation and growth of such networks, on the surface or in the depth of a structural specimen, can be studied.
The aim of the present work is to study the influence of microstructure and of the stress gradien... more The aim of the present work is to study the influence of microstructure and of the stress gradient on the fatigue crack growth in a two-phase austenitic-ferritic stainless steel in specimens with regions of confined plasticity. Direct optical observations and potential drop technique calibrated via the finite element method are used to measure the surface crack size and its depth and to determine the in-depth and surface crack growth. The effect of stress and strain gradients on the crack propagation kinetics and the crack shape is evaluated and discussed.
Low Cycle Fatigue and Elasto-Plastic Behaviour of Materials, 1998
Unidirectional and multilayer composites are usually subjected to bending, and often fail in fati... more Unidirectional and multilayer composites are usually subjected to bending, and often fail in fatigue by interlaminar shearing. This work studies new experimental conditions in fatigue, using a three-point-bending test with predominant shearing, while tensile/compressive stresses are significant. The experimental device geometry is validated under monotonic loading by comparison between finite element results and experimental observations. The deflection amplitude vs. fatigue life curve is used as a pseudo-Wohler curve. An approximate drawing of maximum deformation vs. fatigue life curve is proposed using Fournier's model. Experimental results in fatigue are well accounted for by this model.
Tensile and low-cycle fatigue tests were performed on a 316LN austenitic stainless steel at 300 a... more Tensile and low-cycle fatigue tests were performed on a 316LN austenitic stainless steel at 300 and 77 K. The tensile and low-cycle fatigue properties were obtained and analysed in terms of the influence of temperature on the plastic deformation process and the formation of strain-induced martensite. The martensite content was evaluated using measurements of magnetic saturation. No α'-martensite was detected at 300 K under either monotonic or cyclic straining. On the contrary, at 77 K, strain-induced martensitic transformation is responsible for the higher elongation in tension and the secondary hardening observed on hardening/softening curves in low-cycle fatigue. The induced martensite content in tensile tests is a function of strain which deviates from Angel's model. In low-cycle fatigue, it is a function of the strain level and the accumulated plastic strain. At a given total strain amplitude, the decrease of temperature from 300 to 77 K results in the decrease of plasti...
Revue de Métallurgie, 1994
Ecf17 Brno 2008, Feb 7, 2013
Astm Special Technical Publication, 1994
Materials Science Forum, Feb 15, 2005
J Phys Iv, 2002
Nous proposons une méthodologie de mesure automatique de la surface de plasticité pendant des cha... more Nous proposons une méthodologie de mesure automatique de la surface de plasticité pendant des chargements cycliques biaxiaux. La surface de plasticité est mesurée de manière discrète avec un faible offset de déformation plastique (2 10^{-5}) et des paramètres de mesure optimisés. La méthode est appliquée à un acier inoxydable duplex soumis à un trajet de chargement non-proportionnel. Les résultats montrent une distorsion et une translation de la surface de plasticité sans changement de taille. La méthode présentée permet également de vérifier la normalité de la vitesse d'écoulement plastique par rapport à la surface de plasticité.
Key Engineering Materials, 2007
In this work, the formation of fatigue cracks is considered as a nucleation process due to the de... more In this work, the formation of fatigue cracks is considered as a nucleation process due to the development of a characteristic microstructure formed just beneath the specimen surface. Strain controlled cyclic tests were carried out at room temperature at total strain ranges εt = 0.8 and 1.2% in flat specimens of SAF 2507 Duplex Stainless Steel (DSS). The results show that for this DSS, at εt = 0.8%, the correlation between phases (Kurdjumov-Sacks crystallographic relation) plays an important role in the formation of microcracks. On the other hand, at εt = 1.2%, microcracks initiate in the ferritic phase and the K-S relation does not seem to affect the formation of the cracks.
Key Engineering Materials, 2008
The cyclic hardening–softening response, the cyclic stress–strain curve and the substructure evol... more The cyclic hardening–softening response, the cyclic stress–strain curve and the substructure evolution of a high nitrogen duplex stainless steel S32750 have been evaluated and the results compared with reference to low and medium nitrogen duplex stainless steels, S32205 and S32900 grades, respectively. The beneficial effects of nitrogen on the cyclic properties of most modern alloys have been analyzed in terms of the flow stress components, i.e. the internal and the effective stress.
Scripta Metallurgica et Materialia, 1993
ABSTRACT
Low Cycle Fatigue and Elasto-Plastic Behaviour of Materials—3, 1992
Materials Science and Engineering, 1983
Low Cycle Fatigue and Elasto-Plastic Behaviour of Materials—3, 1992
Procedia Engineering, 2010
Cyclic variations of temperature may damage a component, or a part of a component. Such a phenome... more Cyclic variations of temperature may damage a component, or a part of a component. Such a phenomenon is called 'thermal fatigue'. In most cases, multiple cracking occurs. It is also sometimes called 'crazing'. The so- called SPLASH experiment, described in this paper, allows the experimental reproduction of crack networks similar to those actually observed in some parts of pressurized water reactors. Thus, the initiation and growth of such networks, on the surface or in the depth of a structural specimen, can be studied.
The aim of the present work is to study the influence of microstructure and of the stress gradien... more The aim of the present work is to study the influence of microstructure and of the stress gradient on the fatigue crack growth in a two-phase austenitic-ferritic stainless steel in specimens with regions of confined plasticity. Direct optical observations and potential drop technique calibrated via the finite element method are used to measure the surface crack size and its depth and to determine the in-depth and surface crack growth. The effect of stress and strain gradients on the crack propagation kinetics and the crack shape is evaluated and discussed.
Low Cycle Fatigue and Elasto-Plastic Behaviour of Materials, 1998
Unidirectional and multilayer composites are usually subjected to bending, and often fail in fati... more Unidirectional and multilayer composites are usually subjected to bending, and often fail in fatigue by interlaminar shearing. This work studies new experimental conditions in fatigue, using a three-point-bending test with predominant shearing, while tensile/compressive stresses are significant. The experimental device geometry is validated under monotonic loading by comparison between finite element results and experimental observations. The deflection amplitude vs. fatigue life curve is used as a pseudo-Wohler curve. An approximate drawing of maximum deformation vs. fatigue life curve is proposed using Fournier's model. Experimental results in fatigue are well accounted for by this model.
Tensile and low-cycle fatigue tests were performed on a 316LN austenitic stainless steel at 300 a... more Tensile and low-cycle fatigue tests were performed on a 316LN austenitic stainless steel at 300 and 77 K. The tensile and low-cycle fatigue properties were obtained and analysed in terms of the influence of temperature on the plastic deformation process and the formation of strain-induced martensite. The martensite content was evaluated using measurements of magnetic saturation. No α'-martensite was detected at 300 K under either monotonic or cyclic straining. On the contrary, at 77 K, strain-induced martensitic transformation is responsible for the higher elongation in tension and the secondary hardening observed on hardening/softening curves in low-cycle fatigue. The induced martensite content in tensile tests is a function of strain which deviates from Angel's model. In low-cycle fatigue, it is a function of the strain level and the accumulated plastic strain. At a given total strain amplitude, the decrease of temperature from 300 to 77 K results in the decrease of plasti...
Revue de Métallurgie, 1994
Ecf17 Brno 2008, Feb 7, 2013
Astm Special Technical Publication, 1994
Materials Science Forum, Feb 15, 2005
J Phys Iv, 2002
Nous proposons une méthodologie de mesure automatique de la surface de plasticité pendant des cha... more Nous proposons une méthodologie de mesure automatique de la surface de plasticité pendant des chargements cycliques biaxiaux. La surface de plasticité est mesurée de manière discrète avec un faible offset de déformation plastique (2 10^{-5}) et des paramètres de mesure optimisés. La méthode est appliquée à un acier inoxydable duplex soumis à un trajet de chargement non-proportionnel. Les résultats montrent une distorsion et une translation de la surface de plasticité sans changement de taille. La méthode présentée permet également de vérifier la normalité de la vitesse d'écoulement plastique par rapport à la surface de plasticité.
Key Engineering Materials, 2007
In this work, the formation of fatigue cracks is considered as a nucleation process due to the de... more In this work, the formation of fatigue cracks is considered as a nucleation process due to the development of a characteristic microstructure formed just beneath the specimen surface. Strain controlled cyclic tests were carried out at room temperature at total strain ranges εt = 0.8 and 1.2% in flat specimens of SAF 2507 Duplex Stainless Steel (DSS). The results show that for this DSS, at εt = 0.8%, the correlation between phases (Kurdjumov-Sacks crystallographic relation) plays an important role in the formation of microcracks. On the other hand, at εt = 1.2%, microcracks initiate in the ferritic phase and the K-S relation does not seem to affect the formation of the cracks.
Key Engineering Materials, 2008
The cyclic hardening–softening response, the cyclic stress–strain curve and the substructure evol... more The cyclic hardening–softening response, the cyclic stress–strain curve and the substructure evolution of a high nitrogen duplex stainless steel S32750 have been evaluated and the results compared with reference to low and medium nitrogen duplex stainless steels, S32205 and S32900 grades, respectively. The beneficial effects of nitrogen on the cyclic properties of most modern alloys have been analyzed in terms of the flow stress components, i.e. the internal and the effective stress.
Scripta Metallurgica et Materialia, 1993
ABSTRACT
Low Cycle Fatigue and Elasto-Plastic Behaviour of Materials—3, 1992
Materials Science and Engineering, 1983
Low Cycle Fatigue and Elasto-Plastic Behaviour of Materials—3, 1992