Examinando por Materia "Heat treating"

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    Development of as-cast dual matrix structure (DMS) ductile iron
    (ELSEVIER SCIENCE SA, 2013-03-20) Murcia, S. C.; Paniagua, M. A.; Ossa, E. A.; Murcia, S. C.; Paniagua, M. A.; Ossa, E. A.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
    Ductile iron is widely used due to its low cost and higher ductility than other cast irons. There has been an increased interest during the last years in improving the strength of these materials by means of heat-treating to obtain dual matrix structures (DMS) that enhance the properties found in Austempered Ductile Irons (ADI). This work studies the fabrication of DMS ductile cast irons with martensitic and bainitic structures in the as-cast condition, reducing costs related to heat treating processing while improving the mechanical behavior of the material. Cast irons alloyed with nickel ranging from 0% up to 7% were produced in order to evaluate the effect of Ni-Mo content on the phase transformations and mechanical properties of the material. The effect of cooling rate in phase transformations and mechanical properties were studied using molds with different wall thicknesses, finding that addition of Nickel and Molybdenum improves substantially the strength of the as-cast ductile iron, making unnecessary any further heat treating according to the level of properties desired. © 2012 Elsevier B.V.
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    Simulation of the evolution of floor covering ceramic tiles during the firing
    (SPRINGER, 2013-04-01) Peris-Fajarnes, Guillermo; Defez, Beatriz; Serrano, Ricardo; Ruiz, Oscar E.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Laboratorio CAD/CAM/CAE
    Finding the geometry and properties of a ceramic tile after its firing using simulations, is relevant because several defects can occur and the tile can be rejected if the conditions of the firing are inadequate for the geometry and materials of the tile. Previous works present limitations because they do not use a model characteristic of ceramics at high temperatures and they oversimplify the simulations. As a response to such shortcomings, this article presents a simulation with a three-dimensional Norton's model, which is characteristic of ceramics at high temperatures. The results of our simulated experiments show advantages with respect to the identification of the mechanisms that contribute to the final shape of the body. Our work is able to divide the history of temperatures in stages where the evolution of the thermal, elastic, and creep deformations is simplified and meaningful. That is achieved because our work found that curvature is the most descriptive parameter of the simulation. Future work is to be realized in the creation of a model that takes into account that the shrinkage is dependent on the history of temperatures. © 2012 ASM International.