ISSN 2594-5300
32º Seminário de Aciaria — Vol. 01 , num. 32 (2001)
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Abstract
The influence of top slag chemistry has been studied on a LCAK steel grade at the SIDERAR steel plant. Samples of slag and steel were collected and the temperature was measured for five heats at four stages during ladle furnace treatment. Cleanliness was determined using optical microscopy for number and size distribution and Scanning Electron Microscopy (SEM) for composition. The results show that the best removal of inclusions is obtained during the sulfur refining period, probably due to strong gas stirring that promotes inclusion growth through turbulent collisions and flotation mechanisms. It was also shown that the number of inclusions increased during the final stirring period due to late aluminum additions and insufficient stirring time. Alumina inclusions were found to contain more CaO and MgO in heats where sulfur refining was more effective, indicating that good slag-steel interaction affects inclusion composition. A theoretical study based on plant results showed that equilibrium sulfur distribution increases when: (i) the (%FeO)/(%Al₂O₃) ratio increases, (ii) aluminum content in steel increases, and (iii) temperature decreases.
The influence of top slag chemistry has been studied on a LCAK steel grade at the SIDERAR steel plant. Samples of slag and steel were collected and the temperature was measured for five heats at four stages during ladle furnace treatment. Cleanliness was determined using optical microscopy for number and size distribution and Scanning Electron Microscopy (SEM) for composition. The results show that the best removal of inclusions is obtained during the sulfur refining period, probably due to strong gas stirring that promotes inclusion growth through turbulent collisions and flotation mechanisms. It was also shown that the number of inclusions increased during the final stirring period due to late aluminum additions and insufficient stirring time. Alumina inclusions were found to contain more CaO and MgO in heats where sulfur refining was more effective, indicating that good slag-steel interaction affects inclusion composition. A theoretical study based on plant results showed that equilibrium sulfur distribution increases when: (i) the (%FeO)/(%Al₂O₃) ratio increases, (ii) aluminum content in steel increases, and (iii) temperature decreases.
Keywords
slag, ladle refining, desulfurization, inclusion, LCAK steel
slag, ladle refining, desulfurization, inclusion, LCAK steel
How to cite
Johansson, Eva K. M.; Jönsson, Pär G.; Madias, Jorge; Petroni, Jorge O..
INFLUENCE OF TOP SLAG CHEMISTRY ON MICRO INCLUSION CHARACTERISTICS AND SULFUR REFINING FOR LCAK STEEL,
p. 303-312.
In: 32º Seminário de Aciaria,
Belo Horizonte, Brasil,
2001.
ISSN: 2594-5300, DOI 10.5151/2594-5300-32Aciaria-303-312
