Influence of slag composition on bearing steel cleanness

Ma, Wenjun; Bao, Yan; Wang, M.; Zhao, Dongnan

doi:10.1179/1743281212y.0000000096

Cited by 30 publications

(27 citation statements)

References 14 publications

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“…Conditions which can be improved in this context, are those of the secondary steel refining processes, where the chemical composition and effective viscosity of the slag used has a significant effect on the kinetics of the refining reactions. Furthermore, these conditions add to the removal and dissolution of inclusions throughout the steel-slag interface, as well as facilitate the removal of gases from liquid steel [1][2][3][4][5][6][7][8][9] . In order to achieve these conditions, metallurgists often prefer completely liquid slags in the ladle treatment.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Secondary Refining Slag Parameters with Focus on Inclusion Cleanliness

et al. 2018

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Secondary refining slag samples with different chemical compositions (45-54 % CaO, 7-13 % Al 2 O 3 , 20-29 % SiO 2 , 9-16 % MgO, 0-5 % CaF 2) were investigated to verify the influence of their effective viscosity on inclusion cleanliness of DIN 38MnS6 in a steelmaking plant. The steel samples were collected during the production process for analysis of inclusions. Using the commercial software FactSage 6.4, thermodynamic calculations were performed to determine the effective viscosity, solid fraction, liquid fraction and MgO saturation point of these slags at 1560ºC. The results showed that all the slags were saturated in MgO, revealing a better protection of the ladle refractory. The addition of 2 to 5 % of CaF 2 reduced the effective viscosity values for the analyzed slags from 0.45 Pa•s to 0.10 Pa•s , in comparison to the slags without the addition of CaF 2 , with an effective viscosity of 0.40 Pa•s, 0.27 Pa•s and 0.22 Pa•s, decreasing the level of non-metallic inclusions for some of the analysed heats. However, it was detected during the manufacturing process that high slag fluidity and re-oxidation events continue to be a challenge associated with reducing the level of non-metallic inclusions.

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Section: Introductionmentioning

confidence: 99%

Analysis of Secondary Refining Slag Parameters with Focus on Inclusion Cleanliness

et al. 2018

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“…Comparando-se as figuras 3 e 4, observa-se que o melhor teor de MgO da escória se dá entre 6 e 8%, o que também confere com o descrito na literatura. De acordo com Ma [5], a eficiência da escória no refino secundário se dá com melhores resultados para teores mais baixos de MgO. Ma observou que, baixando-se a relação CaO/Al2O3 obteve-se uma melhoria no teor de oxigênio total, resultando em teores mais baixos.…”

Section: Resultsunclassified

“…Segundo os estudos realizados por Ma[5] e por Yoon[3] para os aços rolamento, o aumento do índice de basicidade binária leva a uma diminuição dos teores de oxigênio total. Ao analisar-se a figura 5, sem que nenhuma variável tivesse sido fixada, observa-se a tendência descrita na literatura.…”

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Análise Da Influência De Parâmetros De Escórias De Refino Secundário E De Processo Na Limpeza Inclusionária De Aços

Silva¹,

Bielefeldt²,

Vilela³

2014

ABM Proceedings

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ResumoA escória utilizada no refino secundário deve possuir propriedades adequadas para que auxilie no controle inclusionário dos aços. Tendo isto em vista, há vários parâmetros que devem ser levados em conta para se obter uma escória ótima que irá auxiliar na limpeza dos aços. Como uma técnica de medição, o valor de oxigênio total no banho está diretamente relacionado com o número de inclusões óxidas presentes no aço líquido. O presente trabalho tem como objetivo geral o acompanhamento da limpeza inclusionária por meio dos teores de oxigênio total presentes nos aços, para variáveis selecionadas de escória e de processo. A partir das análises químicas de amostras de um aço alto carbono acalmado ao alumínio, foram gerados gráficos com os valores de oxigênio total em função dos parâmetros %CaO/%Al2O3, %FeO+%MnO, basicidade binária, tempo de flotação na torre do lingotamento contínuo e pick-up de nitrogênio; seguido da análise dos resultados obtidos e sua comparação com os dados da literatura. Pode-se então concluir que, para as análises anteriormente citadas, o aço apresentou resultados coerentes com a literatura para todas as análises. Palavras-chave: Escórias; Composição química; Oxigênio total; Flotação. Abstract The slag utilized in the secondary refining must possess adequate properties so that assist in the control of the inclusions of steel. With this in view, there are various parameters that must be taken in account to obtain an optimal slag that will go assist in the cleaning of the steel. As a technical for measuring, the total oxygen content in the bath is directly related with the number of the oxides inclusions presents in the liquid steel. The present work aims as general objective the accompaniment of the cleaning of the inclusions by means of the levels of the total oxygen presents in steels, for variables selected of the slag and of process. From chemistry analysis of the samples of the a steel high carbon aluminum killed, were generated graphics with the values of the total oxygen in function of the parameters %CaO/%Al2O3, %FeO+%MnO, %CaO/%SiO2, time of flotation in the continuous casting turret and pick-up of nitrogen; followed by analysis of the results obtained and comparison with data of the literature. Can be concluded, considering the analysis previously mentioned, steel has shown results consistent with the literature for all analysis.

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“…The high basicity of refining slag is used, and the compositions show in Table 1. 22) In the process of VD it is ensured that the vacuum time is not less than 12 min and the soft blowing time is not less than 15 min.…”

Section: Experimental Procedures and Samplingmentioning

confidence: 99%

Effect of Mg and Ca Treatment on Behavior and Particle Size of Inclusions in Bearing Steels

Bao

Wang

et al. 2014

ISIJ Int.

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The effect of Mg and Ca treatment on the behavior and the particle size of inclusions in bearing steels were studied by industrial experiments and thermodynamic calculations. The results showed that the excess addition of Mg wires is not conducive to control the total oxygen content in bearing steel because of the secondary oxidation. The irregular and clustered Al2O3 inclusions are the dominant in the aluminium killed bearing steels. The different quantity Mg wires were added, which can change the irregular and clustered Al2O3 inclusions into the spherical MgO or MgO·Al2O3 inclusions. When the Ca addition is insufficient, the Al2O3 and MgO·Al2O3 inclusions could not completely change into the spherical CaO-MgOAl2O3 system inclusions. By the three-dimensional morphologies analyze, Al2O3 inclusions are easy to gather and the size of clustered Al2O3 inclusions is large. By the Mg or Ca treatment, the size of Al2O3 inclusions can be reduced, but the large size CaO inclusions are brought into steel after the Ca treatment.

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Influence of slag composition on bearing steel cleanness

Cited by 30 publications

References 14 publications

Analysis of Secondary Refining Slag Parameters with Focus on Inclusion Cleanliness

Analysis of Secondary Refining Slag Parameters with Focus on Inclusion Cleanliness

Análise Da Influência De Parâmetros De Escórias De Refino Secundário E De Processo Na Limpeza Inclusionária De Aços

Effect of Mg and Ca Treatment on Behavior and Particle Size of Inclusions in Bearing Steels

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