通过作者查论文: Josep Antonio Benito

文章题目页数

作者: Antoni Roca, Aránzazu Villuendas, Ignacio Mejía, Josep Antonio Benito, Núria Llorca-Isern, Jordi Llumà, Jordi Jorba
摘要: The information in the basic references about the relation between elastic constants and particularly Young’s modulus (E) behavior and plastic deformation indicates that this parameter is constant or almost constant. At the beginning of the XX century several authors indicated that E of some metals decreased when cold deformation increased and detected reductions up to 15% in steels, aluminum, copper, brass... In the last years this behavior is taking into account during the finite-element analysis of sheet metal stamping or other plastic deformation processes. This work includes an extensive review of papers of our research team and of other authors related with the behavior of Young’s modulus during plastic deformation of some metallic alloys. This parameter can diminish up to 10% by plastic deformation (tension test) in iron, aluminum, and stainless steel (UNS S 30403) but remains practically unaltered in aluminum alloys deformed before or after aging. Results of Young’s modulus in nanostructured copper and copper alloys determined by ultrasonic technique are also presented. Additional results of Young’s modulus of UNS G10180 and UNS G10430 steels measured during loading and unloading steps in tension test are also included. High differences in the E values were detected between both steps.
2382
作者: Josep Antonio Benito, Jordi Jorba, Antoni Roca
4435
作者: I. Mejía, C. Maldonado, Josep Antonio Benito, Jordi Jorba, Antoni Roca
摘要: This research work analyses the effect of cold working level produced by drawing, on the work hardening exponent of 0.18 and 0.43 % C ferrite-pearlite steels. Such analysis is carried out by means of true stress-true strain curves derived from uniaxial tension tests. The work hardening exponent behaviour was determined by using Hollomon and differential Crussard-Jaoul models. It is found that the work hardening exponent decreases as a function of the applied cold-drawing level, and negative values were obtained when differential analysis is used. The results indicate that the Hollomon analysis shows some deviations from the experimentally determined true stress - true strain curves while the differential Crussard-Jaoul analysis fits better when two work hardening exponents are considered. This analysis establishes two exponents for different stages of plastic deformation which are determined by the sharp slope change in the plot of ln (d σ/d ε) - ln ε.
37
作者: Josep Antonio Benito, Robert Tejedor, Rodriguez Rodríguez-Baracaldo, Jose María Cabrera, Jose Manuel Prado
摘要: This paper reviews the ductility of nanostructured and ultrafine iron obtained using a variety of methods. Mechanical milling of powder and subsequent hot consolidation, one of the most popular methods offer high mechanical strength but poor ductility. Improvements made in the consolidation processes and the introduction of final heat treatments, in addition to new approaches such as spark plasma sintering and high pressure torsion, have increased the total plastic strain of nanostructured iron. The development of bimodal structures enables the existence of strain hardening and more uniform deformation. The paper also includes a steel study, which finds that the hardness of milled powder and the role of carbon atoms inside ferrite grains make it more difficult to improve the ductility of nanostructured samples.
197
作者: Jordi Llumà, Josep Antonio Benito, Antoni Roca, Jose María Cabrera, Jose Manuel Prado
摘要: A study has been carried out on the grain size distribution of cylindrical compacts obtained by consolidation of iron powder severely deformed by mechanical milling. Consolidation has been performed in two consecutive steps: cold and hot conditions. The hot one was done at two temperatures, namely 425 and 475°C. After milling, the iron powder has a grain size of 8 nm (± 4 nm) with an average hardness of 800 HV. After hot compaction the grain size increases up to 50 nm, especially at 475°C where a small fraction of grains reach larger values than the average. The grain size was evaluated by two different techniques, X-Ray Diffraction and Transmission Electron Microscopy. Results showed some differences between both methods. The advantage of using TEM is that grain size distribution, and not only the average size, can be obtained. Small discs were also obtained from the compacted specimen in order to fracture them on a “ball on three balls” equipment. The fracture behaviour of the samples was then studied by SEM.
1007
作者: Josep Antonio Benito, Robert Tejedor, Rodriguez Rodríguez-Baracaldo, Jose María Cabrera, Jose Manuel Prado
摘要: Samples of nanostructured and ultrafine grained steels with carbon content ranging from 0.05 to 0.55%wt. have been obtained by a warm consolidation process from mechanically milled powders and subsequent heat treatments. In general, homogeneous grain size distributions were obtained except for the low-carbon steel in which a bimodal grain size distribution was observed when it was heat treated at high temperatures. The stress-strain response has been studied by means of compression tests. Nanostructured materials showed high strength but poor results in terms of ductility. In the low-ultrafine range (mean grain size between 100-500 nm) the three materials showed an increase in the ductility with strain softening. Finally, when the average grain size was close to 1 µm samples showed larger ductility and strain hardening.
617
作者: I. Mejía, Josep Antonio Benito, Jordi Jorba, Antoni Roca
3661
作者: Lucia Suarez, Josep Antonio Benito, Pablo Rodriguez-Calvillo, Daniel Casellas, Yvan Houbaert, Roumen H. Petrov, Jose Manuel Prado
摘要: Low alloy transformation-induced plasticity aided (TRIP) steels have attracted much interest over the last years. TRIP steels were initially developed for automotive applications as they offer an excellent combination of strength and ductility at reasonable costs. These excellent mechanical properties mainly arise from a complex multiphase microstructure of a ferrite matrix and a dispersion of multiphase grains of bainite, martensite and metastable retained austenite. The relevant influence of microstructure on physical and mechanical properties makes metallographic study essential for an appropriate understanding and improvement of the mechanical behavior. An accurate microstructural characterization and quantification of the amount of the different constituents is indispensable to know how the stresses and strains are distributed within the different microstructural constituents. Among the different characterization methods commonly used electron backscatter diffraction (EBSD) appears to be the unique technique able to observe retained austenite grains often no larger than 1 μm. The present work shows the evolution of retained austenite while straining. Microstructural and textural evolution after different strains was examined by optical microscopy OM, EBSD and XRD techniques on TRIP800 steel. EBSD technique appears as a powerful tool for characterizing the complex multiphase steel microstructure and provides an accurate evaluation of the local crystallographic texture. It allows to measure orientation gradients within individual grains of each different phase. The distinction between some phases is observed.
3531
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