Examination of carbon partitioning into austenite during tempering of bainite

The redistribution of carbon after tempering of a novel nanocrystalline bainitic steel consisting of a mixture of supersaturated ferrite and retained austenite has been analyzed by atom probe tomography. No direct evidence supporting the additional carbon enrichment of austenite beyond that initially achieved during the bainite heat treatment was obtained during subsequent tempering of this high carbon, high silicon steel.The authors gratefully acknowledge the support of the Research Fund for Coal and Steel and the Spanish Ministry of Science and Innovation for funding this research under the contracts RFSR-CT-2008-00022 and MAT2007 – 63873, respectively. Research at the Oak Ridge National Laboratory SHaRE User Facility was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. A.J. Clarke gratefully acknowledges support from Los Alamos National Security, LLC, operator of the Los Alamos National Laboratory under contract number DE-AC52-06NA25396 with the U.S. Department of Energy and the Advanced Steel Processing and Products Research Center, a National Science Foundation Industry/University Cooperative Research Center at the Colorado School of Mines and the Inter-American Materials Collaboration ProgramPeer reviewe

Simplified multistage computational approach to assess the fatigue behavior of a niti transcatheter aortic valve during in vitro tests: A proof-of-concept study

reserved7siNowadays, transcatheter aortic valve (TAV) replacement is an alternative to surgical therapy in selected high risk patients for the treatment of aortic stenosis. However, left ventricular contraction determines a severe cyclic loading for the implanted stent-frame, undermining its long-term durability. Technical standards indicate in vitro tests as a suitable approach for the assessment of TAV fatigue behavior: generally, they do not specify test methods but require to test TAV in the worst loading conditions. The most critical conditions could be different according to the specific valve design, hence the compartment where deploying the valve has to be properly identified. A fast and reliable computational methodology could significantly help to face this issue. In this paper, a numerical approach to analyze Nickel-Titanium TAV stent-frame behavior during in vitro durability tests is proposed. A simplified multistage strategy was adopted where, in each stage, only two of the three involved components are considered. As a proof-of-concept, the method was applied to a TAV prototype. Despite its simplifications, the developed computational framework gave useful insights into the stent-frame failures behavior during a fatigue test. Numerical results agree with experimental findings. In particular, the most dangerous condition was identified among a number of experimental tests, where different compartments and pressure gradients were investigated. The specific failure location was also correctly recognized. In conclusion, the presented methodology provides a tool to support the choice of proper testing conditions for the in vitro assessment of TAV fatigue behavior.mixedPetrini, Lorenza; Dordoni, Elena; Allegretti, Dario; Pott, Desiree; Kütting, Maximilian; Migliavacca, Francesco; Pennati, GiancarloPetrini, Lorenza; Dordoni, Elena; Allegretti, Dario; Pott, Desiree; Kütting, Maximilian; Migliavacca, Francesco; Pennati, Giancarl

La Botánica en el Jardín de Migas Calientes

[ES] En este artículo se aportan nuevos datos sobre la constitución física del antiguo Jardín Botánico de Migas Calientes, fundado en 1755, de acuerdo a la documentación inédita conservada en la Biblioteca dl Palacio de Santa Cruz de Valladolid. Hemos elaborado un nuevo análisis de la labor educativa de us profesores y publicamos la relación de la biblioteca botánica de José Quer, situada en el actual jardín Botánico de Madrid, añadiendo, en todos los casos posibles, la identificación de las obras que se mencionan.[EN] In this article new formation of the physical constitution of the old Botanical Garden of Calientes Migas Calientes, established in 1735, are contributed, according lo the unpublished documentation conserved in the Library of the Palace of Santa Cruz de Valladolid. We have elaborated a new analysis of the educational work of its professors and we published the relation f the botanical library oí José Quer. located in the actual Botanical Garden of Madrid, adding, in al1 the possible cases, the identification of the works which are mentioned.Peer reviewe