ESTUDIO DEL ORIGEN DE INCLUSIONES EN EL REPARTIDOR DE COLADA CONTINUA DE TERNIUM SIDERAR
STUDY ABOUT THE ORIGIN OF INCLUSIONS IN THE TUNDISH OF TERNIUM SIDERAR
Martin, Alejandro; Méndez, Juan Andres; Romero, Michel; Gresia, Gustavo Di; Cicutti, Carlos
http://dx.doi.org/10.4322/tmm.2012.047
Tecnol. Metal. Mater. Min., vol.9, n4, p.265-270, 2012
Resumen
Para la producción de aceros con altas exigencias de calidad es indispensable conocer con precisión las distintas fuentes de generación de inclusiones, de modo de optimizar las prácticas metalúrgicas para minimizar su presencia. El uso de elementos trazadores en la escoria ha mostrado ser una herramienta eficaz para determinar el origen de las inclusiones en los productos de colada continua. En el presente trabajo se realizaron diferentes experiencias utilizando BaCO3 para trazar la escoria de distribuidor. Empleando esta metodología se siguieron diferentes secuencias y se tomaron muestras de planchones en distintos momentos de las coladas. Las muestras fueron exhaustivamente analizadas por medio de microscopía óptica y electrónica de barrido. Se evaluan la densidad, distribución de tamaño y composición de las inclusiones observadas. Los resultados de estos análisis revelan la presencia de inclusiones con Ba en los planchones cercanos al momento del cambio de cuchara. En cambio, en las muestras correspondientes al período estacionario de la colada no se detectan este tipo de inclusiones. Las inclusiones con Ba se presentan con mayor frecuencia en las coladas avanzadas de secuencia y en aquellos casos donde el nivel de distribuidor tuvo un descenso más marcado en el momento del cambio de cuchara. Estos resultados sugeren que la emulsificación producida por el impacto de la corriente de acero líquido al abrir la nueva cuchara puede generar inclusiones que son arrastradas a los moldes. El efecto es más marcado cuando hay una mayor acumulación de escoria en el repartidor. Finalmente, se realizaron también distintas pruebas utilizando elementos modificadores de flujo dentro del distribuidor, analizándose su impacto en la generación y eliminación de las inclusiones.
Palabras clave
Inclusiones, Distribuidores, Escorias
Abstract
For the production of steels with high quality standards is essential to know accurately the different sources that generate inclusions, in order to optimize the steelmaking practices and to minimize their frequency. The use of tracer elements in the slag has shown an effective tool to determine the origin of inclusions in continuous casting slabs. In the present study different experiences were performed using BaCO3 like a tracer in the tundish slag. Using this methodology slab samples were taken at different times of the castings. The samples were exhaustively analyzed by optical microscopy and SEM/EDS. The density, size distribution and composition of the inclusions observed were evaluated. The results of this analysis revealed the presence of inclusions with Ba in the slab during the transitory state (ladle change). For another hand, samples from the stationary state did not detect this type of inclusions. Ba inclusions occur most frequently in advanced casting sequence and in those cases where the tundish level has a weight reduction during the ladle change. These results suggest that the emulsification produced by the impact of the flow of liquid steel can generate inclusions. The effect is more pronounced when there is a greater accumulation of slag in the tundish. Finally, various tests are also performed using flow modifiers within the tundish, analyzing their impact on the generation and elimination of non-metallic inclusions.
Keywords
Inclusions, Tundishes, Slags
Referências
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8 FUHR, F. et al. Application of slag tracers to investigate the source of non-metallic inclusions. Ironmaking and Steelmaking, v. 34, n. 6, p. 463-70, 2007. http://dx.doi.org/10.1179/174328107X174609
9 MARTÍN, A.; MARTÍN, M.; CICUTTI, C. Utilización de trazadores para determinar origen de macroinclusiones: informe 1º. Buenos Aires: Instituto Argentino de Siderurgia, 2008. (Reporte interno. PRO 08 058)
10 MARTÍN, A. et al. Utilización de trazadores en la escoria de repartidor para evaluar el origen de macroinclusiones (seguimiento 3). Buenos Aires: Instituto Argentino de Siderurgia, 2009. (Reporte interno. PRO 09 025)
11 RAY, S. et al. Modelling of tundish slag entrainment during ladle change. In: AISTECH CONFERENCE, 2008, Pittsburgh. Proceedings… [S.l.: s.n.], 2008. v. 2.
12 SOLORIO-DÍAZ, G. et al. Fluid dynamics of vortex formation in tundish operations: physical modeling. Steel Research International, v. 78, n. 3, p. 248-53, 2007.
13 SATISH KUMAR, D. et al. Forced flotation of inclusions in tundish. Ironmaking and Steelmaking, v. 36, n. 6, p. 470-5, 2009. http://dx.doi.org/10.1179/174328108X393849
14 KITANO, Y. et al. Technology of reducing non-metallic inclusions in tundish in continuous casting. In: ISS ELECTRIC FURNACE CONFERENCE, 56., 1988, New Orleans. Proceedings... S.n.t. p. 419-423.
2 CRAMB, A.; BYRNE, M. Tundish slag entrainment at Bethlehem’s Burns Harbor (Indiana) slab caster. Iron and Steelmaker, v. 15, n. 12, p. 49-56, 1988.
3 KASUNUMA, J. et al. Continuous casting of highly clean steel slab. ISS Steelmaking Conference Proceedings, v. 67, p. 17-19, 1984.
4 PRABHU, N.; PINKOWSKI, J. Measuring cold rolled surface quality based on data collected at the caster. ISS Steelmaking Proceedings, v. 73, p. 491-5, 1990.
5 ENGLISH, T. et al. The use of rare earth oxide tracers in the determination of inclusion sources and origins at British Steel, Scunthorpe Works, Clean Steel 4, v. 1, p. 262-82, 1992.
6 NAM, S. et al. Improvement of steel cleanliness in ladle exchange period. ISS Steelmaking Proceedings, v. 78, p. 551-6, 1995.
7 KIM, D. et al. Improvement of cleanness in melt of ferritic stainless steel by control of stirring power. ISS Steelmaking Proceedings, v. 84, p. 343-55, 2001.
8 FUHR, F. et al. Application of slag tracers to investigate the source of non-metallic inclusions. Ironmaking and Steelmaking, v. 34, n. 6, p. 463-70, 2007. http://dx.doi.org/10.1179/174328107X174609
9 MARTÍN, A.; MARTÍN, M.; CICUTTI, C. Utilización de trazadores para determinar origen de macroinclusiones: informe 1º. Buenos Aires: Instituto Argentino de Siderurgia, 2008. (Reporte interno. PRO 08 058)
10 MARTÍN, A. et al. Utilización de trazadores en la escoria de repartidor para evaluar el origen de macroinclusiones (seguimiento 3). Buenos Aires: Instituto Argentino de Siderurgia, 2009. (Reporte interno. PRO 09 025)
11 RAY, S. et al. Modelling of tundish slag entrainment during ladle change. In: AISTECH CONFERENCE, 2008, Pittsburgh. Proceedings… [S.l.: s.n.], 2008. v. 2.
12 SOLORIO-DÍAZ, G. et al. Fluid dynamics of vortex formation in tundish operations: physical modeling. Steel Research International, v. 78, n. 3, p. 248-53, 2007.
13 SATISH KUMAR, D. et al. Forced flotation of inclusions in tundish. Ironmaking and Steelmaking, v. 36, n. 6, p. 470-5, 2009. http://dx.doi.org/10.1179/174328108X393849
14 KITANO, Y. et al. Technology of reducing non-metallic inclusions in tundish in continuous casting. In: ISS ELECTRIC FURNACE CONFERENCE, 56., 1988, New Orleans. Proceedings... S.n.t. p. 419-423.
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