Articoli di riviste: "Essais de traction. nanoindentation"

1

Yang, Xiao Fang, e Jian Lu. "Nanostructured 316 Stainless Steel Prepared under Traction by Surface Mechanical Attrition Treatment". Materials Science Forum 614 (marzo 2009): 201–6. http://dx.doi.org/10.4028/www.scientific.net/msf.614.201.

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A nanostructured 316 austenitic stainless steel sample was prepared under traction using a new surface mechanical attrition treatment (SMAT) system. The microstructure of the surface layer of the SMATed sample was characterized using an optical microscope and transmission electron microscope (TEM). Microhardness on the cross-section was investigated by nanoindentation measurement. Results showed that a deeper nanostructured layer was obtained in comparison with that of the sample SMATed without traction.

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Fradet, Clémence, Florian Lacroix, Gaëlle Berton, Stéphane Méo e Eric Le Bourhis. "Extraction des proprietes mecaniques locales d’un elastomere par nanoindentation : developpement des protocoles et application". Matériaux & Techniques 105, n. 1 (2017): 109. http://dx.doi.org/10.1051/mattech/2017013.

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La réponse mécanique locale d’un fluoroélastomère est présentée au travers de résultats de nanoindentation. Les propriétés des élastomères présentent notamment une dépendance à la vitesse de sollicitation et sont ainsi impactées par les variables du protocole expérimental choisies, telles que la force maximale appliquée ou les vitesses de chargement. Cette caractéristique, intrinsèque à ce type de matériaux, est considérée avec soin dans le cadre d’essais à échelle globale et doit, au même titre, faire l’objet d’une attention particulière lors d’essais de nanoindentation. L’objectif de cette étude est d’appréhender l’impact de la dépendance au temps des élastomères lors de leur caractérisation en nanoindentation. In fine, les investigations doivent pouvoir mener à une méthodologie robuste capable de donner des mesures quantitatives des propriétés mécaniques locales d’élastomères de pièces réelles industrielles. Ce papier dresse donc une description de la technique de nanoindentation appliquée aux élastomères et discute les résultats qui apparaissent clairement dépendants de la manière dont les essais sont conduits. Enfin, les éléments apportés par cette prospection ont été appliqués à la caractérisation d’un composite multicouche caoutchouc/polymère. Cette étude applicative a prouvé l’aptitude de la nanoindentation à détecter des gradients de propriétés au sein du composite.

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Cubero, Henri, Jean-Philippe Fauvarque, Gaëlle Farizy, Jean-Christophe Sangleboeuf e Jean-Louis Chermant. "Essais de traction in-situ de composites à matrices céramiques". Annales de Chimie Science des Matériaux 30, n. 6 (31 dicembre 2005): 637–47. http://dx.doi.org/10.3166/acsm.30.637-647.

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4

Klipfel, Y. L., F. Besse e L. Haenny. "Contrôle de qualité : essais de traction en série sur une machine conventionnelle". Matériaux & Techniques 75, n. 10-11 (1987): 391–97. http://dx.doi.org/10.1051/mattech/198775100391.

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5

Li, Xiaobao, e Changwen Mi. "Nanoindentation hardness of a Steigmann–Ogden surface bounding an elastic half-space". Mathematics and Mechanics of Solids 24, n. 9 (5 ottobre 2018): 2754–66. http://dx.doi.org/10.1177/1081286518799795.

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Previous studies demonstrate that, for nanostructures under transverse bending, the effective Young modulus is appreciably greater (in magnitude) than that of the same elements under axial loads. Therefore, in addition to the conventional residual surface tension and membrane stiffness, the curvature dependence of surface energy is desired for inhomogeneously strained nanostructures. In this paper, we aim to reevaluate the size-dependent nanoindentation hardness of an elastic half-space subjected to nanosized frictionless traction, through the use of both the curvature-independent Gurtin–Murdoch and the curvature-dependent Steigmann–Ogden models of surface elasticity. The nanoindentation problem is solved by the integration of Boussinesq’s method of displacement potentials and Hankel integral transforms. As examples, the effects of residual surface tension, membrane stiffness, and bending rigidity of the half-space boundary are parametrically analyzed in detail for a uniform circular pressure and a concentrated normal force. The observations in semianalytical calculations suggest a significant difference in the nanoindentation hardnesses predicted from the two popular models of surface mechanics. In most cases, the inclusion of bending rigidity results in smaller displacements and stresses, and therefore higher indentation hardness. Based on physically interpretable numerical values of surface material properties, we show that a curvature-dependent model of surface elasticity is required in order to characterize the size-dependent feature of nanoindentation problems correctly.

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Revaux, T., J. D. Guérin, J. P. Bricout e J. C. Tissier. "Essais de traction à haute température après refusion in situ : application aux aciers et aux fontes". Revue de Métallurgie 93, n. 12 (dicembre 1996): 1551–62. http://dx.doi.org/10.1051/metal/199693121551.

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Serratrice, Jean-François. "Une méthode d'interprétation des essais effectués sur site sur des boulons à ancrage réparti sollicités en traction". Revue Française de Géotechnique, n. 171 (2022): 4. http://dx.doi.org/10.1051/geotech/2022005.

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Les boulons à ancrage réparti sont utilisés dans le domaine des soutènements et des renforcements des sols et des roches. Leur comportement s'étudie au moyen d'essais d'arrachement ou par auscultation de boulons instrumentés. Une méthode d'interprétation de ces différents types d'essais est proposée. Fondée sur un calcul au module de réaction, elle met en jeu un boulon pris individuellement et sollicité dans sa direction axiale. La méthode a été appliquée à l’interprétation d'une dizaine d'essais d'arrachement et de cinq boulons radiaux instrumentés mis en place en tunnel ou dans une paroi clouée, d'après des données issues de la littérature. L'article présente une partie des résultats de cette étude en commençant par un aperçu des travaux de recherche effectués dans ce domaine. La méthode de calcul est ensuite présentée. Les exemples d'interprétation de deux essais d'arrachement sont commentés alors, pour lesquels trois lois de réaction sont mises en œuvre (bilinéaire, exponentielle et trilinéaire). Deux procédures sont proposées pour effectuer le choix de la loi de réaction et l'identification de ses paramètres. La méthode a été appliquée ensuite à un boulon radial instrumenté mis en place en tunnel.

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Camurri, Carlos, Claudia Carrasco, Antonio Pagliero e Rodrigo Leite. "Influence of the Impurities on Cathodic Copper on the Ductility of Copper Wires". Materials Science Forum 706-709 (gennaio 2012): 899–906. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.899.

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The main characteristic of cathodic copper is the concentration of impurities because it depends on mechanical characteristics, i.e. ductility, of the derived copper wires. The standard mechanical tests that evaluate their ductility, are quick elongation and spiral elongation tests. The results of these essais shown that there is not a clear correlation among the impurities content in cathodes and wire ductility. Also, the two mechanical tests actually used are not able to discriminate differences on the copper ductility associated to variations in impurities concentration, at ppm level. In this work, a design of new specimen for traction test, with a reduced gage length of 10 mm that clearly discriminate differences on copper ductility associated to variations in impurities concentration is exposed. In addition, from traction tests to copper wires and observation of their fracture surfaces by means of SEM and EDS it is concluded that the principal impurity affecting the ductility of the copper wires is the oxygen, mainly incorporated during the melting of the cathodes and casting of the rods. Also, the traditional annealing to the samples previous to the tensile tests must to be avoid since produces a dispersion on the matrix of the Cu2O oxides and so the deleterious effect of the oxygen on the copper ductility cannot be detected.

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Yoon, Jang Hyuk, Seong Jin Kim e Ho Jang. "Molecular Dynamics Simulation of Stress Induced Grain Boundary Migration during Nanoindentation Experiments". Materials Science Forum 449-452 (marzo 2004): 89–92. http://dx.doi.org/10.4028/www.scientific.net/msf.449-452.89.

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Molecular dynamics (MD) simulation was performed to study the stress induced grain boundary migration caused by the interaction of dislocations with a grain boundary. The simulation was carried out in a Ni block (295020 atoms) with a Σ = 5 (210) grain boundary and an embedded atom potential for Ni was used for the MD calculation. Stress was provided by indenting a diamond indenter and the interaction between Ni surface and diamond indenter was assumed to have a fully repulsive force to emulate a traction free surface. Results showed that the indentation nucleated perfect dislocations and the dislocations produced stacking faults in the form of a parallelepiped tube. The parallelepiped tube was comprised of four {111} slip planes and it contained two pairs of parallel dislocations with Shockley partials. The dislocations propagated along the parallelepiped slip planes and fully merged onto the Σ = 5 (210) grain boundary without emitting a dislocation on the other grain. The interaction of the dislocations with the grain boundary induced the migration of the grain boundary plane in the direction normal to the boundary plane and the migration continued as long as the successive dislocations merged onto the grain boundary plane. The detailed mechanism of the conservative motion of atoms at the grain boundary was associated with the geometric feature of the Σ = 5 (210) grain boundary.

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Sternberg, Anna K., Liubov Izmaylova, Volker U. Buck, Irmgard Classen-Linke e Rudolf E. Leube. "An Assessment of the Mechanophysical and Hormonal Impact on Human Endometrial Epithelium Mechanics and Receptivity". International Journal of Molecular Sciences 25, n. 7 (27 marzo 2024): 3726. http://dx.doi.org/10.3390/ijms25073726.

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The endometrial epithelium and underlying stroma undergo profound changes to support and limit embryo adhesion and invasion, which occur in the secretory phase of the menstrual cycle during the window of implantation. This coincides with a peak in progesterone and estradiol production. We hypothesized that the interplay between hormone-induced changes in the mechanical properties of the endometrial epithelium and stroma supports this process. To study it, we used hormone-responsive endometrial adenocarcinoma-derived Ishikawa cells growing on substrates of different stiffness. We showed that Ishikawa monolayers on soft substrates are more tightly clustered and uniform than on stiff substrates. Probing for mechanical alterations, we found accelerated stress–relaxation after apical nanoindentation in hormone-stimulated monolayers on stiff substrates. Traction force microscopy furthermore revealed an increased number of foci with high traction in the presence of estradiol and progesterone on soft substrates. The detection of single cells and small cell clusters positive for the intermediate filament protein vimentin and the progesterone receptor further underscored monolayer heterogeneity. Finally, adhesion assays with trophoblast-derived AC-1M-88 spheroids were used to examine the effects of substrate stiffness and steroid hormones on endometrial receptivity. We conclude that the extracellular matrix and hormones act together to determine mechanical properties and, ultimately, embryo implantation.

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Juarez, Cesar, Gerardo Fajardo e Pedro Valdez. "Caractérisation microstructurale des fibres naturelles pour des matériaux composites à base de ciment". Canadian Journal of Civil Engineering 36, n. 3 (marzo 2009): 449–62. http://dx.doi.org/10.1139/l09-009.

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Le comportement mécanique des bétons renforcés de fibres naturelles dépend principalement de l’adhérence entre la fibre et la matrice de ciment. Cette adhérence a aussi une certaine influence sur le type d’endommagement de ces matériaux. Cette recherche a été menée sur des fibres naturelles de lecheguilla (Agave lecheguilla). Des essais chimiques, physiques et mécaniques tels que la détermination de la composition chimique, la morphologie, la porosité, l’absorption d’eau et les résistances à la traction et à la flexion ont été réalisés en utilisant ces fibres naturelles. Des observations à l’interface fibre–matrice de ciment ont aussi été effectuées à l’aide du stéréoscope pour évaluer l’effet du milieu alcalin et de différents rapports eau/ciment (E/C) sur la performance de mortier fibré. On a constaté que la résistance mécanique à la traction et à la flexion du matériau composite augmente, d’une part, avec l’augmentation de la longueur et, d’autre part, avec la diminution du volume de fibres utilisé. Le principal type de défaillance observée est l’arrachement des fibres. De plus, l’adhérence entre les fibres et la matrice de ciment est modifiée par les changements volumétriques et l’absorption d’eau relativement élevée. Néanmoins, cette adhérence peut être substantiellement améliorée en faisant un traitement superficiel des fibres à l’aide de solutions chimiques, comme le xylène, et en utilisant des faibles rapports E/C.

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Badel, Éric, e Patrick Perré. "Détermination des propriétés élastiques d'éléments individuels du plan ligneux du chêne par des essais de traction sur micro-éprouvettes". ANNALS OF FOREST SCIENCE 56, n. 6 (1999): 467–78. http://dx.doi.org/10.1051/forest:19990603.

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13

Math, S., V. Jayaram e S. K. Biswas. "Deformation and failure of a film/substrate system subjected to spherical indentation: Part II. Prediction of failure modes in a thin TiN film deposited on a compliant elastic substrate". Journal of Materials Research 21, n. 3 (1 marzo 2006): 783–90. http://dx.doi.org/10.1557/jmr.2006.0095.

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We have demonstrated previously, using nanoindentation, that the film thickness and substrate plasticity, the important two external variables in the film layer, control the failure of the film in a mutually exclusive way. In this work, we used a non-iterative Hankel transform method to analyze the stresses in an elastic film bound to an elastic substrate by a no-slip boundary condition and subjected to a Hertzian traction. We vary the substrate compliance by two orders of magnitude to generate interfacial mismatch stresses, which mimic the corresponding changes found in a real-life elastic film on an elastic-plastic substrate when the hardness of the substrate is changed. The analysis is found to reproduce faithfully the experimental trends, which showed that normal load and interfacial stresses generated by strain mismatch drive different modes of fracture depending on the film thickness in a mutually exclusive way. This validation paves the way for this theoretical technique to be used to design multilayered film structures.

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Tayebi, Noureddine, Thomas F. Conry e Andreas A. Polycarpou. "Reconciliation of nanoscratch hardness with nanoindentation hardness including the effects of interface shear stress". Journal of Materials Research 19, n. 11 (1 novembre 2004): 3316–23. http://dx.doi.org/10.1557/jmr.2004.0425.

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The definitions of hardness from nanoscratch and nanoindentation analyses with a spherical indenter were compared and shown to be mathematically equivalent for the case of zero interface shear stress (surface traction). The definition of nanoindentation hardness was taken as the ratio of the resultant force to the area of contact projected on a plane normal to the line of action of the resultant force, whereas in the case of the nanoscratch technique, the hardness and interfacial shear stress were related to the measured normal and lateral forces in a nanoscratch experiment, as well as to the cross-sectional area of the groove. The two definitions of hardness were then applied to nanoscratch experimental data from material systems covering a wide range of hardness values. The calculated values of hardness from the two definitions were based on the contact area, determined from the scratch residual profile and the elastic recovery of the plastically deformed surface, and yielded the same values of hardness within experimental error. The contact angle, and thus the contact area, was shown experimentally to be sensitive to interface shear stress: a positive increase in interface shear stress led to a reduction in contact area as compared to the case of a frictionless contact. For a material with given hardness, normal indenter force, and contact area, a positive or negative interface shear stress is balanced by a positive or negative change, respectively, in the lateral force about the value needed to maintain a static balance for a frictionless nanoscratch contact. A comparison of these effects with experimental data indicates that very hard materials tend to have negative to zero interface shear stress, which correlates to a sink-in effect, whereas the soft materials tend to have positive interface shear stress, which correlates to a pileup effect.

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Berthelot, Patrick, Michel Maron, Alexandre Reynaud, Sabika Ghegediban e Maxime Fonty. "Intérêt des essais par la méthode des vérins embarqués – exemple de l’essai de barrette mené sur le bassin d’orage Austerlitz à Paris". Revue Française de Géotechnique, n. 176 (2023): 3. http://dx.doi.org/10.1051/geotech/2023022.

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L’article revient sur les travaux récents du bassin d’orage Austerlitz réalisé à Paris, et pour lequel la conception du radier ancré a su tirer les bénéfices d’un essai de chargement sur une barrette de fondation de type foré boue. Le contexte réglementaire de ce type d’ouvrage et l’intérêt de mener des essais de chargement pour des fondations en traction sont d’abord rappelés. L’essai sur la barrette de fondation de 2,8 m par 1,0 m, profonde de 73,5 m et ancrée dans la craie campanienne a nécessité la mise en œuvre, pour la première fois en France, d’un système de vérins embarqués appelés cellules Osterberg, qui a permis l’application par palier d’une charge allant jusqu’à 27 MN à 64 m de profondeur. L’article décrit la conception, la réalisation et les résultats de l’essai. Une interprétation est proposée et conduit à retenir une valeur de frottement limite pour ce type de fondation dans la craie campanienne au droit du site autour de 250 à 300 kPa. Ces résultats sont enfin mis en perspective avec une brève description de la manière dont la conception de l’ancrage du radier a pu évoluer à la suite de l’essai.

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Ndepete, Cyrille Prosper, Raoul Zaguy-Guerembo, Aime Martinien Deganai Gbongo, Luce Marie-Paul Regakouzou, Victoire Olivia Ngaissona Namndouta e José Kpeou-Kolengue. "Valorisation des déchets plastiques en matériaux de construction". European Scientific Journal, ESJ 18, n. 21 (30 giugno 2022): 320. http://dx.doi.org/10.19044/esj.2022.v18n21p320.

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Cette étude consiste à valoriser les déchets plastiques qui polluent l’environnement, en proposant une méthode de recyclage de ces déchets, en les transformant en liant pouvant être utilisés pour la fabrication des matériaux de revêtement routier et de sol intérieur et extérieur. La méthodologie utilisées consiste à utiliser les déchets plastiques de basse densité (PBD) collectées dans six (06) arrondissements de Bangui comme liant dans une matrice sableuse provenant de la rivière Oubangui. Au total 54 éprouvettes (pavés) ont été fabriquées à différents dosages (10 ; 15 ; 20 ; 25 ; 30 ; 40 ; 45 et 50% des teneurs en plastique) et ont été soumis à des essais physiques et mécaniques. Les résultats de ces essais montrent que la porosité décroit de 4,99 à 1,21 % lorsque la teneur en plastique passe de 25 à 50 %. La résistance à la compression augmente de 5,15 à 30,61 MPa lorsque la teneur en plastique varie de 10 % à 30 %. Elle chute progressivement jusqu’à atteindre 11,49 MPa quand la teneur en plastique dépasse 35%. La résistance à la traction (Rt) augmente de 0,9 à 2,43 MPa lorsque la teneur en plastique varie de 10 à 35 % avant de chuter progressivement jusqu’atteindre 1,28 MPa lorsque la teneur en plastique atteint 50 %. This study consists of recovering plastic waste that pollutes the environment, by proposing a method of recycling this waste, by transforming it into a binder that can be used for the manufacture of materials for road surfacing and interior and exterior flooring. The methodology used consists of using low-density plastic waste (LDP) collected in six (06) districts of Bangui as a binder in a sandy matrix from the Oubangui River. A total of 54 specimens (blocks) were manufactured at different dosages (10; 15; 20; 25; 30; 40; 45 and 50% of plastic contents) and were subjected to physical and mechanical tests. The results of these tests show that the porosity decreases from 4.99 to 1.21% when the plastic content increases from 25 to 50%. The compressive strength increases from 5.15 to 30.61 MPa when the plastic content varies from 10% to 30%. It gradually drops until it reaches 11.49 MPa when the plastic content exceeds 35%. The tensile strength (Rt) increases from 0.9 to 2.43 MPa when the plastic content varies from 10 to 35% before gradually decreasing to 1.28 MPa when the plastic content reaches 50%.

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"Prévisions sur les résultats des essais de barre de traction". Journal of Terramechanics 24, n. 3 (gennaio 1987): 247. http://dx.doi.org/10.1016/0022-4898(87)90045-0.

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Yang, B., R. M. Rethinam e S. Mall. "Modeling and Analysis of Cylindrical Nanoindentation of Graphite". Journal of Applied Mechanics 76, n. 1 (5 novembre 2008). http://dx.doi.org/10.1115/1.2999412.

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Graphite at the nanoscale is modeled as a material system consisting of a stack of parallel plates buffered by an elastic material. While the plates represent individual graphene sheets, the buffer material models the Van der Waals interaction between the graphene sheets. As such, the loading on graphite at the nanoscale is characterized by the membrane force, the bending moment, and the shear force in the graphene sheets. Cylindrical nanoindentation of graphite is analyzed by applying a special boundary element method that employs Green’s function for multilayers with platelike interfaces. Because Green’s function satisfies the traction-free surface, the interfacial displacement continuity and the interfacial traction discontinuity conditions, only the indentation surface area where the boundary condition is altered, are numerically discretized. Numerical results of cylindrical nanoindentation are presented. It is shown that the bending moment and the shear force in the graphene sheets are concentrated around the edge of contact, consistent with the singularities existing in the second and the third derivatives of the surface displacement in the reduced case of a semi-infinite homogeneous solid under cylindrical contact. Kinks of single, double, and triple joints are related to the bending moment, the shear force, and the concentrated force, respectively.

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Sanchez-Huerta, D., T. De la Mora-Ramírez, M. A. Doñu-Ruiz, N. López-Perrusquia e J. V. Cortés-Suarez. "Characterization of Adherence Steels Hardened Superficially". MRS Proceedings 1616 (2014). http://dx.doi.org/10.1557/opl.2014.232.

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ABSTRACTThis study evaluates the behavior of the adherence layers - sawn flat iron boride formed on the surface of steels used in manufacturing industry in Mexico. In steels AISI 1018, AISI 8620 and AISI 316 was characterized this behavior, boriding thermochemical treatment with box technique, with a processing temperature of 1273 °K, with an exposure time of 8 hours. Furthermore the adherence is assessed by the Rockwell C hardness technique prescribed by the German standard VDI 3198 of traction, this impact test qualitatively determine the type of adherence formed three thermochemical steels treated by the technique of boriding. Moreover optical microscopy determines the type of film morphology FeB/ Fe2B of each of the materials exposed to a boriding, also shows the thicknesses of the phases generated in the surface type in all three steels boriding. Phase presence boride FeB/Fe2B was determined by X -ray diffraction (XRD). Technique for scanning electron microscopy (EDS) was evaluated qualitatively the presence of FeB/Fe2B of boronizing. Otherwise determines the hardness and elastic modulus by nanoindentation technique of the phases present in the three steels. Lastly, AISI 1018 and AISI 8620 are bounding scale H1 to H3, the AISI 316 steel has an adherence of H3 to H6 under German standard VDI 3198.

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Articoli di riviste sul tema "Essais de traction. nanoindentation"

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