P. Cugy
ArcelorMittal, APERAM ALLOYS IMPHY, Department Member
International audienc
Ultra high strength Fe-Mn-C austenitic steels with low Stacking Fault Energy (SFE) have been studied for more than fifty years [1]. They offer a great potential for reducing automotive body weight through their formability and their high... more
Ultra high strength Fe-Mn-C austenitic steels with low Stacking Fault Energy (SFE) have been studied for more than fifty years [1]. They offer a great potential for reducing automotive body weight through their formability and their high mechanical properties. Tensile strength levels higher than 1000 MPa
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Austenitic Fe-Mn-C steels are Ultra High Strength Steels which may be used for the production of deep drawn automotive parts containing extremely high residual stress and strain levels. In consequence, hydrogen absorption occurring during... more
Austenitic Fe-Mn-C steels are Ultra High Strength Steels which may be used for the production of deep drawn automotive parts containing extremely high residual stress and strain levels. In consequence, hydrogen absorption occurring during the corrosion process in aqueous environments may enhance the sensitivity of these steels to different kinds of hydrogen-induced damage, in particular Stress Corrosion Cracking (SCC). In order to predict and prevent SCC, it is important to study the behaviour of hydrogen in these austenitic steels exposed to aqueous environments and in particular the dependence on the alloy chemistry and microstructure. SIMS profiles of deuterium introduced by cathodic charging in selected specimens were used to characterize the diffusion of hydrogen in these steels. This allowed to be studied the role of chemical composition and microstructure on the kinetics of H absorption at room temperature. The competition between bulk matrix diffusion and short-circuit diffu...
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Reduction of gas emissions through lightweighting is among the most important goals of steel users. In general, an increase in tensile strength for a given metallurgy is obtained to the detriment of ductility. ARCELOR and TKS have... more
Reduction of gas emissions through lightweighting is among the most important goals of steel users. In general, an increase in tensile strength for a given metallurgy is obtained to the detriment of ductility. ARCELOR and TKS have developed a new super-high strength steel with TWinning Induced Plasticity (TWIP) for weight reduction and improved crash resistance named X-IP 1000. This austenitic product, which is based on a high manganese alloy metallurgy, has a tensile strength greater than 1000 MPa for a total elongation superior to 50%. In this paper we present the various mechanical properties and compare them with conventional high strength steels (HSLA, DP, TRIP, etc.) and formable grades (DDQ). The tensile and forming properties are studied using standard test methods (stretching, bending, etc.). In addition, spot welding parameters and the mechanical behaviour of spot welds are presented. The crash resistance potential is investigated using dynamic tensile testing and dynamic ...
It is proposed to develop and identify a probabilistic two-scale model for HCF that accounts for the failure of samples but also for the thermal effects during cyclic loadings in a unified framework. The probabilistic model is based on a... more
It is proposed to develop and identify a probabilistic two-scale model for HCF that accounts for the failure of samples but also for the thermal effects during cyclic loadings in a unified framework. The probabilistic model is based on a Poisson point process. Within the weakest link theory, the model corresponds to a Weibull law for the fatigue limits. The
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Résumé: Afin d'étendre un modèle de prévision de courbe de Wöhler à partir de courbe d'échauffement aux chargements proportionnels multiaxiaux, un essai d'échauffement biaxial sur éprouvette en croix a été développé.... more
Résumé: Afin d'étendre un modèle de prévision de courbe de Wöhler à partir de courbe d'échauffement aux chargements proportionnels multiaxiaux, un essai d'échauffement biaxial sur éprouvette en croix a été développé. L'éprouvette sandwich a été optimisée ...
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Résumé/Abstract The serrations observed on the stress-strain curves of a Fe-22Mn-0.6 C wt.% steel present all the phenomenological features associated with dynamic strain ageing, including negative strain rate sensitivity and thermal... more
Résumé/Abstract The serrations observed on the stress-strain curves of a Fe-22Mn-0.6 C wt.% steel present all the phenomenological features associated with dynamic strain ageing, including negative strain rate sensitivity and thermal activation. We show that the ...