Carlos Adolfo Hernandez Carreon | Instituto Politécnico Nacional (original) (raw)

Papers by Carlos Adolfo Hernandez Carreon

MRS Advances, 2019

The hot rolling process reduces a slab passing through a series of work-rolls to obtain a strip o... more The hot rolling process reduces a slab passing through a series of work-rolls to obtain a strip of target thickness. Developing robust, efficient, and accurate simulation methods improve the process. This research aims to minimize the hot rolling time, bending of work rolls, thermal crown, and wear of work rolls, subject to some process constraints. The problem solution is by using a multi-objective genetic algorithm with four function objectives. The second generation of the Non-dominated Sorting Genetic Algorithm was chosen to solve the problem of this research. A probed constitutive model has been incorporated into the algorithm to compute the flow stress as a function of the chemical composition of steels. The algorithm implemented to minimize the four objectives proposed obtained the optimal schedule and associated makespan.

Revista Latinoamericana de Metalurgia y Materiales

En este trabajo se presentan los resultados del estudio por microscopia electrónica de transmisió... more En este trabajo se presentan los resultados del estudio por microscopia electrónica de transmisión (MET) y EDX de los precipitados inducidos por deformación de NbC en un acero microaleado al niobio, deformado en caliente en un laminador dúo reversible escala laboratorio. Se dan los resultados del estudio mediante MET de las diferencias de forma, tamaño, número de partículas por unidad de área y distribución de los precipitados a lo largo de la microestructura. Se muestran los análisis de EDX y el estudio por pérdida de energía de electrones (PEELS) realizados en la matriz del acero y de los precipitados.

Research in Computing Science, 2016

The problem of Scheduling Hot Rolling Pass of Steels is very complex because it has large spaces ... more The problem of Scheduling Hot Rolling Pass of Steels is very complex because it has large spaces search for solutions. The aim of this work was the Multi-Objective Optimization (MOO) of hot rolling steel sheets in a finishing train of six steps, implementing the second generation of Nondominated Sorting Genetic Algorithm (NSGA-II). It was used two different crossover (AG1 y AG2) operators and two objective functions. These were the total time of rolling and bending of the work rolls. Two kinds of computational experiments were performed: a) Search for the best solution, b) benchmarking of both NSGA-II configurations. For each experiment was obtained 3000 solutions. Rolling time, separation roll force, and exit thickness for each rolling stand are calculated. A flow stress constitutive model for roll force was used, valid for any low, medium carbon and Nb, Ti, V microalloyed steels. The solutions are reported, choosing some of them between 100 based on the lower computing time. The 100 solutions were generated in times lower than 70 s. AG1 had lower computing times AG2. The NSGA-II implementation minimized both the rolling time as crown of the work rolls, at low computational costs and ensuring that the flatness of strip will always be lower than international standards.

The International Journal of Advanced Manufacturing Technology, 2017

Steady- and transient-state solutions are developed to predict temperature, streamlines, stress, ... more Steady- and transient-state solutions are developed to predict temperature, streamlines, stress, and viscosity distributions during the friction stir welding of dissimilar carbon steels AISI/SAE 1008 and 1078. The mass, momentum, and energy transport equations are solved using a Eulerian formulation within the computational fluid dynamics package FLUENT in the plates of dissimilar steels being joined. Viscoplastic behavior in the stir zone is supposed. Both Medina and Hernandez flow stress and Perzyna viscoplastic models are used to model this behavior. The Medina and Hernandez model calculates the flow stress based on the Zener–Hollomon parameter, which is valid for large deformations and high strain rates and takes into account the steel chemical composition of any structural steels having low or medium carbon contents. The present work couples this flow stress model to the continuity, momentum, and energy transport equations. Temperature-dependent thermal properties are taken from the literature. A comparison of temperature cycles taken from published experimental data and those obtained by simulation is presented. Results indicate that the steady-state simulation can provide solutions more quickly than simulation using the transient model. However, the latter simulation provides temperature, stress, viscosity, and volume fraction distributions that are more detailed than those that the former simulation provides, with the distributions being asymmetric at welding times longer than 30 s. Volume fraction distributions are more symmetric for a rotational speed ? = 450 rpm and a welding velocity U = 0.31 mm s -1. The shape of the stir region is strongly related to the temperatures on the advancing side (AISI 1008 steel) and retreating side (AISI 1078 steel) and the thermo-mechanical properties of the steels; the lobular shapes correspond to those found experimentally.

ISIJ International, 1994

Using torsional tests and applying the back extrapolation methodthe kinetics of the static recrys... more Using torsional tests and applying the back extrapolation methodthe kinetics of the static recrystallization of hot deformed austenite has been studied in three microalloyed steels with different vanadiumcontents and this has been modelled at temperatures above and below the static recrystallization critical temperature (SRCT). The SRCT has been found to be a function of the strain, the austenite grain size and naturally the microalloy contents, in this case N and V. A study has also been made of the kinetics of the precipitation induced by the strain and the precipitation-timeHtemperature (PTT) diagrams have been determined for the three steels. The no-recrystallization temperature (T.,) has also been determined and the conclusion was reached that the difference between the T~, and SRCT is mainly due to the austenite grain size, which is smaller in the determination of the T^, dueto the successive recrystallizations which occur before precipitation takes place.

Se resenan los fundamentos del proceso de refusion bajo escorias electroconductoras (pres). Se an... more Se resenan los fundamentos del proceso de refusion bajo escorias electroconductoras (pres). Se analizan algunos conceptos sobre el comportamiento reologico y estructural de los metales. Se revisan los fundamentos tanto del ensayo de torsion como del proceso de laminacion, asi como la equivalencia existente entre ambas formas de deformacion. Se describe el procedimiento experimental para fabricar con el pres 18 aceros -a diferentes niveles de c, mn, si, mo, ti, nb y v-, y para la realizacion de los ensayos de torsion. Se presentan las curvas tension-deformacion eficaces obtenidas de las curvas par-numero de giros experimentales. Se uso un metodo de gauss-newton de soluciones iterativas para determinar las constantes del parametro de zener-hollomon (z), la energia de activacion en funcion de la composicion quimica, la modelizacion de los parametros a y aquellos requeridos para calcular la curva tension-deformacion eficaces, la cual es resultado de la suma de dos ecuaciones, una para e...

Ceramics International, 2013

ABSTRACT Ba0.75Sr0.25TiO3 (BST) thin films have been deposited by Rf-sputtering on nichrome subst... more ABSTRACT Ba0.75Sr0.25TiO3 (BST) thin films have been deposited by Rf-sputtering on nichrome substrates that have been heated in the range from 400 degrees C to 747 degrees C. The films were characterized morphologically and ferroelectrically. The microstructure of thin films was observed using an atomic force microscope to determine rugosity and grain size. The growth of grain size observed was 75 nm and 95 nm at substrate temperatures from 549 degrees C to 747 degrees C, respectively. The ferroelectric properties were determined by hysteresis loops applying an electric field of 110 kV/cm. The films grown at substrate temperatures from 549 degrees C to 747 degrees C show a decrease of the remnant polarization P-r, from 9.87 mu C/cm(2) to 2.23 mu C/cm(2), and of the coercive field strength E-c, from 59.75 kV/cm to 19.86 kV/cm. The films deposited on nichrome had uniform grain size distribution and relatively low surface roughness. (c) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Materials Science Forum - MATER SCI FORUM, 2003

Acta Materialia, 1996

Using hot torsional tests, the influence of the most common elements in low alloy steels (C, Mn, ... more Using hot torsional tests, the influence of the most common elements in low alloy steels (C, Mn, Si, MO) and in microalloyed steels (Ti, V, Nb) on peak strain has been studied. At the temperatures (900, 1000 and 1100°C) and strain rates (0.544, 1.451, 3.628 and 5.224 SK’) at which the tests were carried out all the elements remained in solution during deformation with the exception of titanium which was in part previously precipitated. In these conditions, the results indicate that C, Si and Mn have hardly any influence on the value of peak strain (tp) while MO, V, Ti and particularly Nb considerably increase its value. The study has been completed with the modelling of tp as a function of the Zener-Hollomon parameter and the austenite grain size for all the steels studied, showing
the quantitative influence of the different alloying elements.

Advances in Soft Computing, 2009

... 1º de Mayo y Sor Juana I. de la Cruz S/N. 89440-Cd. ... Proc., p. 755 (1998) 11. Medina, SF, ... more ... 1º de Mayo y Sor Juana I. de la Cruz S/N. 89440-Cd. ... Proc., p. 755 (1998) 11. Medina, SF, Hernández, CA: General Expression of the Zener-Hollomon Parameter as a Function of the Chemical Composition of Low Alloy and the Microalloyed Steels. Acta Metall. ...

Advances in Soft Computing, 2007

This paper presents an application of a genetic algorithm (GA) to the scheduling of hot rolling m... more This paper presents an application of a genetic algorithm (GA) to the scheduling of hot rolling mills. The objective function used is based on earlier developments on flow stress modeling of steels. A hybrid two-phase procedure was applied in order to calculate the ...