Examinando por Autor "Murcia, S. C."

Mostrando 1 - 2 de 2
  • No hay miniatura disponible
    Ítem
    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.
  • No hay miniatura disponible
    Ítem
    Nodule evolution of ductile cast iron during solidification
    (SPRINGER, 2014-04-01) Murcia, S. C.; Ossa, E. A.; Celentano, D. J.; Murcia, S. C.; Ossa, E. A.; Celentano, D. J.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
    Ductile cast irons are ferrous alloys in which precipitation of graphite in the form of spherical nodules is embedded in a metal matrix to obtain ductility on the material. Despite the importance of the shape of the nodules, the models proposed to predict the solidification of ductile irons assume a perfect spherical shape during the growing process up to the final solidification of the material, which is proved not to be the case in all castings depending on the processing conditions. The influence of the process parameters on the geometry of the nodules in ductile irons was experimentally evaluated and a model to predict the evolution of nodules during solidification was proposed. The proposed model for growth predicts changes in the nodule count as well as in the nodularity based on different laws for carbon diffusion according to the solid fraction, helping to understand the trends found experimentally. © The Minerals, Metals & Materials Society and ASM International 2013.