Instituto Tecnológico de Morelia

About: Instituto Tecnológico de Morelia is a education organization based out in Morelia, Mexico. It is known for research contribution in the topics: Electric power system & AC power. The organization has 498 authors who have published 572 publications receiving 4600 citations.

Numerical Simulation of Heat Transfer and Steel Shell Growth in a Curved Slab Mold

Abstract: The main aims of the present research is the study of steel flow under temperature gradient to understand the convective effects on the flow patterns inside the mold and its effects on the shell growth kinetics under more realistic conditions. In order to achieve this, a non-isothermal mathematical model is developed based on the Navier-Stokes equations together with the k-e turbulence model, the volume of fluid model to solve the multiphase system air-slag-steel and a solidification model. Comparing isothermal and non-isothermal results, it is observed that the buoyancy forces are large enough to modify radically the lower recirculation flows inducing shorter and upwards streams; however, the upper recirculation flows do not show strong changes. Shell growth does not necessarily follow a steady parabolic growth and it is more dependent on the washing effects of convective steel streams. Therefore, shell thickness reports heterogeneous and irregular magnitudes through the four faces of the slab. In addition, mold curvature provides uneven shell growth in the inner side of the slab while in the outer side the shell thickness observes a more regular growth. Shell thickness is irregular and discontinuous all around the upper periphery of the slab; therefore, this region is very sensitive to cracking. Finally, the numerical results for liquid steel solidification are compared to published results of shell growth showing a very good qualitative agreement.

Dynamic Stress Intensity Factor of Interfacial Finite Cracks in Orthotropic Materials

Abstract: The elastodynamic response of an infinite non-homogeneous orthotropic material with an interfacial finite crack under distributed normal and shear impact loads is examined. Solution for the stress intensity factor history around the crack tips is found. Laplace and Fourier transforms are employed to solve the equations of motion leading to a Fredholm integral equation on the Laplace transform domain. The dynamic stress intensity factor history can be computed by numerical Laplace transform inversion of the solution of the Fredholm equation. Numerical values of the dynamic stress intensity factor history for some materials are obtained. Interfacial cracks between two different materials and between two pieces of the same material but different fiber orientation are considered. Bimaterial formulation of a crack problem is shown to converge to the mono-material formulation, derived independently, in the limiting case when both materials are the same.

Modeling Study of the Vortex and Short Circuit Flow Effect on Inclusion Removal in a Slab Tundish

Abstract: A mathematical model was developed to study effects of the vortex and the short circuit flow phenomena during tundish operation on the inclusion removal for a wide range of particle diameters. The model was solved using FLUENT® commercial software; for the particle tracking the Lagrangian discrete phase model was employed. Even when the vortexes drag about 50% of the inclusions, the most detrimental phenomenon for inclusion removal is the short circuit flow. It is important to stress that for the global inclusion behavior the removal rate decreases as the tundish level increases. It can be concluded that when increasing the tundish capacity without any flow control device adjustment, the steel cleanliness is deteriorated significantly.

Conversion of Hematite to Iron Carbides by Gas Phase Carbidization

Abstract: The intrinsic conversion rates of hematite (Fe2O3) to carbide (primarily cementite) with a CO-H2 feed-gas have been measured in the temperature range 550 to 650 °C, by employing a micro-thermogravimetric system. As a preliminary analysis phase stability diagrams were developed in a triangular representation to overcome limitations of binary-type diagrams already available in the open literature. In general the reaction sequence was identified as consisting of a high-rate conversion of Fe2O3 to Fe (33-75 %·min-1) followed by conversion of Fe to Fe3C. Two stages of carbidization were identified. For the first stage, the conversion rates were higher, from 55 to 75 %·min-1, depending on the reactor temperature. The rate of carbidization in the second stage region was lower, in the range of 25 to 35 %·min-1. The rate of carbidization was found to increase as temperature decreases, within the range from 600 to 640 °C. A model based on adsorption kinetics was developed which qualitatively describes the behavior observed. After conversion of Fe to Fe3C carbon deposition (sooting) was evident. The catalytic role of cementite (in contrast to Fe) in the heterogeneous sooting-reaction has also been addressed.

Modelling steel flow in a three-strand billet tundish using a turbulence inhibitor

Abstract: A three-strand tundish belonging to a billet caster was water modelled and plant trials were performed to compare the performance of a pouring box and a turbulence inhibitor in terms of melt flow parameters and steel cleanliness. A tailor made turbulence inhibitor for this tundish is useful to accomplish with flow control of fluid turbulence and even melt redirection to all strands. The turbulence inhibitor helps to decrease nitrogen pickup during ladle changes and to float out inclusions towards the covering slag. As a consequence, rod operations to take of alumina deposits from nozzle walls are considerably decreased using a turbulence inhibitor.